FLS2023 - Classification: B - Ring-based Light Sources

Paper	Title	Page
MO2L1	Future of the Multi-bend Achromat
	P. Raimondi ESRF, Grenoble, France
	The implementation of HMBA for upgrades of small and large scale rings will be described. A strategy to go toward a fully diffraction limited source based on HMBA, consistent with large dynamic aperture and long Toushek lifetime will also be presented.
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MO2L2	Storage Ring Based Steady State Microbunching	1
	A. Chao TUB, Beijing, People’s Republic of China
	Powerful light sources are highly desired tools for scientific research and for industrial applications. Electrons are the objects that most readily and easily radiate photons. A natural conclusion follows that one should pursue electron accelerators as the choice tools towards powerful light sources. How to manipulate the electron beam in the accelerator so that it radiates light most efficiently, however, remains to be studied and its physical principle and technical limits be explored and optimized for the purpose. One such proposed concepts is based on the steady state microbunching (SSMB) mechanism in an electron storage ring. We make a brief introduction of the SSMB mechanism and its recent status in this presentation.
	Slides MO2L2 [1.156 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO2L2
About •	Received ※ 25 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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MO2L3	Review of Harmonic Cavities in Fourth-generation Storage Rings	8
	F.J. Cullinan, Å. Andersson, P. Tavares MAX IV Laboratory, Lund University, Lund, Sweden
	Several third generation light-source storage rings have used harmonic cavities to lengthen the electron bunches. With the advent of the fourth generation however, they have become an almost universal feature as the small transverse electron beam sizes make long bunches essential for increasing Touschek lifetime and reducing emittance blow-up from intrabeam scattering. Multiple technological solutions exist for the implementation of harmonic cavities and which to use remains an open question for many facilities. This is therefore a very active area of study in which there is strong collaboration within the community. Avoiding coherent collective beam instabilities is of particular concern. In this talk, I will summarise the results obtained so far. I will also give an overview of the observations made at the MAX IV 3 GeV ring, the first fourth generation storage ring which was commissioned with normal-conducting passive harmonic cavities already installed. Finally, I will discuss potential future directions.
	Slides MO2L3 [3.035 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO2L3
About •	Received ※ 24 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 27 August 2023 — Issued ※ 02 December 2023
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MO3B1	Obtaining Picosecond X-ray Pulses on 4th Generation Synchrotron Light Sources
	X. Huang, J.A. Safranek SLAC, Menlo Park, California, USA A. Zholents ANL, Lemont, Illinois, USA
	Through the 2-frequency crab cavity scheme, fourth generation storage ring light sources offer a unique opportunity to produce intense short X-ray pulses that are ideal for time-resolved user experiments. The short pulses and the high brightness photon beams are simultaneously available at all beamlines in a fully compatible operation mode. Owing to the small momentum compaction factor characteristic in fourth generation storage rings, the vertical emittance contribution due to the coupling between the longitudinal and transverse planes by the crab cavities is greatly reduced, which allows reaching short pulse duration with little constraint on the betatron tunes. We propose to use half-integer aharmonic cavity to simultaneously produce bunch lengthening and shortening in the bunch train to facilitate compatible operation of the normal and short-pulse beams. A concrete case study based on the Advanced Photon Source Upgrade (APS-U) lattice is used to demonstrate the system configuration, requirements, and beam performances.
	Slides MO3B1 [1.817 MB]
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MO3B2	Beam Dynamics Using Superconducting Passive Harmonic Cavities with High Current per Bunch	14
	A. Gamelin, V. Gubaidulin, A. Loulergue, P. Marchand, L.S. Nadolski, R. Nagaoka SOLEIL, Gif-sur-Yvette, France N. Yamamoto KEK, Ibaraki, Japan
	In 4th generation synchrotron light sources, harmonic cavities (HCs) are critical components needed to achieve the required performance. They provide longer bunches, which helps to reduce statistical effects (intra-beam scattering and Touschek effect). In "timing" modes, where the bunch spacing is larger than in conventional modes and the number of particles per bunch is higher, this need is even greater. In this article, we present the beam dynamics in the high current per bunch regime and how it interacts with the single bunch collective effects. In particular, a dipole-quadrupole instability is observed above the microwave threshold and a coupling between the dipole and cavity modes is shown to limit bunch lengthening at low current. The effective gain from the use of HCs in terms of lifetime, emittance, and energy spread is also discussed.
	Slides MO3B2 [1.529 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B2
About •	Received ※ 13 August 2023 — Revised ※ 15 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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MO3B3	Bunch-lengthening RF System Using Active Normal-conducting Cavities	18
	N. Yamamoto, D. Naito, S. Sakanaka, T. Yamaguchi KEK, Ibaraki, Japan A. Gamelin, P. Marchand SOLEIL, Gif-sur-Yvette, France
	Bunch lengthening using a double RF system (fundamental + harmonic cavities) is essential in preserving the extremely low emittance in fourth and future generation synchrotron light rings. Recent studies have revealed that, in many cases, unstable beam motions, as so-called "mode-0" and "periodic transient beam loading" instabilities, prevent from reaching the optimum bunch lengthening condition with low and high beam current, respectively, even in symmetric filling patterns. While reducing the R/Q is beneficial for the latter, it will worsen the former. To achieve an efficient bunch lengthening system, we proposed a promising solution based on a powered TM020-type harmonic cavity with RF feedbacks (RF-FBs), as reported at FLS2018. Based on this concept, we are developing both fundamental and harmonic cavities using the TM020 resonant mode, a kicker cavity having a bandwidth >5MHz, bunch-phase monitor (BPhM) and RF-FBs. In this presentation, we describe our overall bunch lengthening system including cavity and BPhM designs. We also present particle tracking simulation results demonstrating that the bunch lengthening limitations can be alleviated by means of direct RF-FBs*. N. Yamamoto et al., PRAB 21, 012001, 2018. T. Yamaguchi et al., accepted in NIM A. * D. Naito et al, IPAC2021, MOPSB331, 2021. **** N. Yamamoto et al., IPAC23, WEPL161, 2023.
	Slides MO3B3 [2.655 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B3
About •	Received ※ 22 August 2023 — Revised ※ 23 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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MO3B4	Generating High Repetition Rate X-ray Attosecond Pulses in SAPS	22
	W. Liu, X. Liu, Y. Zhao IHEP CSNS, Guangdong Province, People’s Republic of China Y. Jiao, X. Li, S. Wang IHEP, Beijing, People’s Republic of China
	Attosecond, which refers to 10^-18 seconds, is the timescale of electron motion within an atom. Accurate observation of electron motion helps deepen the understanding of microscopic quantum processes such as charge transfer in molecules, wave packet dynamics, and charge transfer in organic photovoltaic materials. To meet the needs of relevant research, the South Advanced Photon Source (SAPS), currently in the design phase, is considering the construction of an attosecond beamline. This paper presents relevant research on achieving high-repetition-rate coherent attosecond pulses on the fourth-generation storage ring at SAPS. Realizing attosecond pulses in a storage ring requires femtosecond to sub-femtosecond-level longitudinal modulation of the beam, and the modulation scheme needs to consider multiple factors to avoid a significant impact on other users. The study shows that with high-power, few-cycle lasers, and advanced beam modulation techniques, the photon flux of attosecond pulses can be significantly enhanced with a minimal impact on the brightness of synchrotron radiation. Adopting high-repetition-rate lasers and precise time delay control, the repetition rate of attosecond pulses at SAPS can reach the megahertz level. Currently, the design wavelength range for attosecond pulses covers the water window (2.3-4.4 nm), which is "transparent" to water but strongly absorbed by elements constituting living organisms. This wavelength range has significant application value in fields such as biology and chemistry.
	Slides MO3B4 [3.400 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B4
About •	Received ※ 23 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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MO4B1	A Review on Injection Schemes
	M. Aiba PSI, Villigen PSI, Switzerland
	Top-up injection into the storage ring is one of the main challenges of fourth generation light sources because of the limited machine aperture. Various new injection schemes have been studied over the past years, and are to be applied to newly constructed storage rings. There may not be single scheme that can be implemented into any storage ring due to the variety of specific needs and constraints. This talk presents an overview of the developments that may eventually help the storage ring designer to find the optimum scheme. The future trend of the top-up injection is also discussed.
	Slides MO4B1 [1.306 MB]
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MO4B2	The Plasma Injector for PETRA IV: Conceptual Design Report
	A. Martinez de la Ossa, I.V. Agapov, S.A. Antipov, R. Brinkmann, Á. Ferran Pousa, S. Jalas, M. Kirchen, W.P. Leemans, A.R. Maier, J. Osterhoff, R.J. Shalloo, M. Thévenet, P. Winkler DESY, Hamburg, Germany
	We present the conceptual design of an alternative injector system based on laser-plasma accelerator technology, to deliver high-quality electron bunches to PETRA IV - the future 4th generation synchrotron light source at DESY. The design consists of a laser-plasma accelerator to produce electron bunches at 6 GeV with state-of-the-art energy spread and stability, and a X-band energy compressor beamline to further reduce the overall beam energy deviations and maximize the charge injection throughput into the PETRA IV storage ring. Driven by the Petawatt upgrade of DESY’s new flagship laser KALDERA, the plasma injector system can be used to top up the PETRA IV storage ring, significantly lowering the load on the conventional injector chain. Ultimately, upon further development of high-efficiency, high-power laser drivers that operate at high repetition rates, the plasma injector could potentially replace the conventional system in the future and dramatically reduce the spatial footprint and energetic cost of the whole injector complex.
	Slides MO4B2 [24.555 MB]
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MO4B3	Development of a Pulsed Injection Stripline for Diamond-II	38
	R.T. Fielder, A. Lueangaramwong, A.F.D. Morgan DLS, Oxfordshire, United Kingdom
	Diamond-II will use a single bunch aperture sharing injection scheme. This applies a strong kick to both the injected and the targeted stored bunch with a very short duration (ideally <3 ns, if disturbance to the adjacent bunches is to be avoided). We have developed a design for the stripline kickers that can meet these requirements while minimising internal reflections and beam impedance. We show an analysis of the electric and magnetic fields produced by the stripline and simulations of the effects on injected and stored beam, and analysis of the wakefields and impedance of the structure.
	Slides MO4B3 [2.164 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO4B3
About •	Received ※ 21 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU1B1	A Highly Competitive Non-Standard Lattice for a 4th Generation Light Source With Metrology and Timing Capabilities	58
	P. Goslawski, M. Abo-Bakr, J. Bengtsson, K. Holldack, Z. Hüsges, A. Jankowiak, K. Kiefer, B.C. Kuske, A. Meseck, R. Müller, M.K. Sauerborn, O. Schwarzkopf, J. Viefhaus, J. Völker HZB, Berlin, Germany
	The PTB, Germany’s national institute for standards and metrology, has relied on synchrotron radiation for metrology purposes for over 40 years and the most prominent customers are lithography systems from ASML/ZEIS. HZB is now working on a concept for a BESSY II successor, based on a 4th generation light source with an emittance of 100 pmrad @ 2.5 GeV. It is essential, that this new facility continues to serve the PTB for metrology purposes. This sets clear boundary conditions for the lattice design, in particular, the need for homogeneous bends as metrological radiation sources. Different Higher-Order-Multi-Bend-Achromat lattices have been developed, based on combined function gradient bends and homogeneous bends in a systematic lattice design approach. All lattices are linearly equivalent with the same emittance and maximum field strength. However, they differ significantly in their non-linear behavior. Based on this analysis, the choice of the BESSY III lattice type is motivated. A special focus is set also on TRIBs (Transverse Resonance Island Buckets) to operate with two orbits as a bunch separation scheme in MBAs, for different repetition rates or for the separation of short and long bunches.
	Slides TU1B1 [7.584 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1B1
About •	Received ※ 23 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU1B2	Low-alpha Storage Ring Design for Steady-State Microbunching to Generate EUV Radiation
	Z. Pan, A. Chao, X.J. Deng, W.-H. Huang, R.K. Li, Z.Z. Li, C.-X. Tang TUB, Beijing, People’s Republic of China
	A new concept is proposed for minimizing the longitudinal emittance of a low momentum compaction factor (low-alpha) storage ring which has the capability to stably store sub-femtosecond electron bunches for the first time. This storage ring is designed for Steady-State microbunching (SSMB) to generate kW level average power EUV radiation. The proposed design approach can be applied to any quasi-isochronous storage rings to yield very high radiation power due to longitudinal coherence of the radiation. We obtain an optimal lattice design by minimizing global and local momentum compaction factors simultaneously and the result of single-particle tracking shows that the electron beam with equilibrium rms bunch length of about 40 nm can be stored in this ring. We also clarify in this type ring, the horizontal emittance will be fixed when beam energy, dipole bending angle and cell tune is fixed. In this type ring, the calculation for IBS effect will be different with traditional rings, we point out where the difference is and give a more convenient calculation for it.
	Slides TU1B2 [1.628 MB]
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TU1B3	Nonlinear Optics From Hybrid Dispersive Orbits	62
	Y. Li, R.S. Rainer, V.V. Smaluk, D. Xu BNL, Upton, New York, USA
	Funding: Supported by US DoE under Contract No. DE-SC0012704 In this paper we present an expansion of the technique of characterizing nonlinear optics from off-energy orbits (NOECO) to cover harmonic sextupoles in storage rings. The existing NOECO technique has been successfully used to correct the chromatic sextupole errors on the MAX-IV machine, however, it did not account for harmonic sextupoles, which are widely used on many other machines. Through generating vertical dispersion with chromatic skew quadrupoles, a measurable dependence of nonlinear optics on harmonic sextupoles can be observed from hybrid horizontal and vertical dispersive orbits. Proof of concept of our expanded technique was accomplished by simulations and beam measurements on the National Synchrotron Light Source II (NSLS-II) storage ring.
	Slides TU1B3 [1.428 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1B3
About •	Received ※ 18 August 2023 — Revised ※ 20 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU1B4	Minimizing the Fluctuation of Resonance Driving Terms for Analyzing and Optimizing the Storage Ring Dynamic Aperture	66
	Z.H. Bai, B.F. Wei USTC/NSRL, Hefei, Anhui, People’s Republic of China A. Loulergue, L.S. Nadolski, R. Nagaoka SOLEIL, Gif-sur-Yvette, France
	Minimization of resonance driving terms (RDTs) of nonlinear magnets such as sextupoles and octupoles is an essential condition for enlarging the dynamic aperture (DA) of a storage ring. We recently studied the correlation between minimizing the fluctuation or variation of RDTs along the ring and enlarging the DA. It was found that minimizing the RDT fluctuations is much more effective than minimizing the commonly-used one-turn RDTs in enlarging the DA, and that reducing low-order RDT fluctuations can also help reduce both higher-order RDT fluctuations and higher-order one-turn RDTs. In this paper, DA analysis based on minimizing RDT fluctuations is further extended. By considering the RDT fluctuations including low- and high-frequency fluctuations, some nonlinear dynamics issues can be explained. DA optimization is also studied based on numerically minimizing RDT fluctuations using genetic algorithms. Large DA can be obtained, and the optimization is performed very fast.
	Slides TU1B4 [3.118 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1B4
About •	Received ※ 23 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU3B1	Machine Learning Applications for Performance Improvement and Developing Future Storage Ring Light Sources
	S.C. Leemann LBNL, Berkeley, USA
	Funding: This research is funded by the US Department of Energy (BES & ASCR Programs), and supported by the Director of the Office of Science of the US Department of Energy under Contract No. DEAC02-05CH11231. This presentation will focus on two recent applications of Machine Learning (ML) to storage ring-based synchrotron light sources. The first example highlights improvement of storage ring performance by use of ML to stabilize the electron beam size at the source points against perturbations from insertion device (ID) motion. The stability of the source size is improved by roughly one order of magnitude through a neural network-based feed-forward that compensates, in a model-independent manner, for ID-induced source size changes before they can occur. In the second example, ML is used to replace many-turn particle tracking in multi-objective genetic algorithms (MOGA) for the design of lattices for demanding future storage rings. By training neural networks to give accurate predictions of nonlinear lattice properties such as dynamic aperture and momentum aperture, the overall MOGA optimization process an be substantially accelerated. Including overhead from training and iterative retraining, MOGA optimization can be accelerated through ML by up to two orders of magnitude, thereby dropping overall optimization campaign runtime even on large clusters from weeks to just hours. Phys. Rev. Lett. 123, 194801 (2019), https://doi.org/10.1103/PhysRevLett.123.194801 ** Nucl. Instrum. Methods Phys. Res., A 1050, 168192 (2023), https://doi.org/10.1016/j.nima.2023.168192
	Slides TU3B1 [35.589 MB]
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TU3B2	Recent Developments of the Toolkit for Simulated Commissioning
	T. Hellert LBNL, Berkeley, California, USA
	Detailed commissioning simulations have become the main tool of error analysis during lattice design of 4th generation storage ring light sources in recent years. The Matlab based Toolkit for Simulated Commissioning provides a high fidelity error model and a user friendly interface and is currently used at several facilities around the world. This contribution will present the toolkit with the highlight on recent developments such as the integration into the ALS control system for automated startup procedures and the transcription into python, enabling large scale parallelization.
	Slides TU3B2 [45.870 MB]
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TU3B3	Pyapas: A New Framework for High Level Application Development at HEPS	77
	X.H. Lu IHEP CSNS, Guangdong Province, People’s Republic of China D. Ji, H.F. Ji, Y. Jiao, J.Y. Li, N. Li, C. Meng, Y.M. Peng, J. Wan, Y. Wei, G. Xu, H.S. Xu, Y.L. Zhao IHEP, Beijing, People’s Republic of China
	The development of high-level application (HLA) is an indispensable part of the light source construction process. With the increase in the scale and complexity of accelerators, the development of HLA will also face many new challenges, such as increased data volume, multiple data types, more parameter channels, and more complex tuning algorithms. So a new framework named Pyapas has been designed for HLA development which aims to provide a high-performance, scalable, flexible, and reliable HLA development framework to meet the needs of large-scale parameter tuning and data processing. Pyapas is designed with a modular concept, decomposing the development needs of HLA into different modules for decoupled development, and calling them through simple interfaces. In the communication module, a singleton factory class is designed to avoid duplicate creation of channel connections, and combined with Qt’s signal-slot mechanism to create non-blocking communication connections, greatly improving the carrying capacity of parameter scale. While a deeply decoupled two-layer physical model module is designed to quickly switch different mathematical models to meet different online computing needs. Moreover, the design of the C/S architecture development module and the rapid creation and management module of the database is helpful for quickly developing complex programs, further enhancing the applicability of Pyapas. This paper will introduce the main feature of Pyapas
	Slides TU3B3 [6.913 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU3B3
About •	Received ※ 30 August 2023 — Revised ※ 31 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023
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TU3B4	Use of Automated Commissioning Simulations for Error Tolerance Evaluation for the Advanced Photon Source Upgrade
	V. Sajaev, M. Borland ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Multi-bend achromat-based light source designs are known to have rather strong focusing and rather small vacuum chambers, which pretty much guarantees difficult commissioning. To ensure the Advanced Photon Source Upgrade* commissioning is possible, the automated commissioning simulations were developed*. The simulations start from trajectory correction in the transport line, go through first-turn correction, trajectory and orbit correction, and complete with lattice and coupling correction. In addition to ensuring smooth commissioning, these simulations proved very useful in evaluating error tolerances under the most realistic conditions. In some cases, this approach allows for significant relaxation of the tolerances. We will describe APS-U automated commissioning simulations and give examples of error tolerance evaluations. M. Borland et al., "The Upgrade of the Advanced Photon Source", in Proc. IPAC’18, Vancouver, Canada, Apr.-May 2018, pp. 2872-2877 **V.Sajaev, "Commissioning simulations for the aps upgrade lattice," Phys. Rev. Accel. Beams, vol. 22, p. 040102, 2019
	Slides TU3B4 [5.581 MB]
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TU4P17	Non-destructive Vertical Halo-monitors on the ESRF Electron Beam	112
	K.B. Scheidt ESRF, Grenoble, France
	The ESRF EBS storage ring has since spring 2022 among its electron beam diagnostics two independent units of vertical Halo-monitors. The principle and the components of this unique diagnostic will be explained in details. It uses the available X-rays in a non-used Front-End, emitted from a 0.57 T standard dipole magnet in the EBS lattice. This instrument measures the so-called "far-away" Halo level, i.e. in a zone of roughly 1-3 mm away from the beam centre, which represents 200-600 times the electron’s vertical beam-size, supposedly Gaussian, of 5 um. It is measured, and expressed quantitively in picoAmp beam current, at 1 Hz rate. Both units are yielding very satisfying and well-correlated results that will be presented in details, and in relation with studies on the electron beam and the accelerator components like variation of current, filling-patterns, vertical emittance, quality of the vacuum, settings of the undulator gaps, collimators, scrapers etc. and also in direct correlation with measurements of our 128 beamloss detectors and beam lifetime.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P17
About •	Received ※ 21 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P18	Nonlinear Dynamics Measurements at the EBS Storage Ring	116
	N. Carmignani, L.R. Carver, L. Hoummi, S.M. Liuzzo, T.P. Perron, S.M. White ESRF, Grenoble, France
	The EBS is a 4th generation synchrotron light source and it has been in user operation since August 2020 at the ESRF. Several measurements to characterise the nonlinear dynamics have been performed in 2023: nonlinear chromaticity, second order dispersion and detuning with amplitude. The results of the measurements are shown and compared with simulations.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P18
About •	Received ※ 23 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P19	Evolution of Equilibrium Parameters Ramp Including Collective Effects in the Diamond-II Booster	120
	R. Husain, R.T. Fielder, I.P.S. Martin DLS, Oxfordshire, United Kingdom P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	Efficient top-up injection into the Diamond-II storage ring will require upgrading the booster lattice for a beam emittance of <20 nm rad and a bunch length of <40 ps, including when operating with high single-bunch charge. The small vacuum chamber dimensions will drive the resistive wall instability and may adversely affect equilibrium parameters along the beam energy ramp. In addition, various diagnostic and vacuum chamber components will generate geometric impedances which may further disrupt the equilibrium parameters. Based on the detailed engineering designs, impedance models of the major components have been simulated using CST Studio and included in ELEGANT tracking simulations of the booster. In addition, the effects of synchrotron radiation emission and intra-beam scattering on the equilibrium parameters during the ramp are studied.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P19
About •	Received ※ 22 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P20	Simulated Commissioning for Diamond-II Storage Ring from On-axis to Off-axis Injection	124
	H.-C. Chao, I.P.S. Martin DLS, Oxfordshire, United Kingdom
	The Diamond-II storage ring commissioning simulations have continued based on the previous results where on-axis injected beams are captured. The next goal is to enlarge the dynamic aperture so that off-axis injection can be achieved. The procedures include beam based alignment, beta-beating correction and linear optics correction. Details of the implementations are discussed and the simulation results are presented. In the end, we are able to reach off-axis injection which allows accumulation.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P20
About •	Received ※ 22 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU4P26	Special Operational Modes for SLS 2.0	127
	J. Kallestrup, M. Aiba PSI, Villigen PSI, Switzerland
	The SLS 2.0 storage ring will achieve low emittance and high brightness while maintaining large dynamic aperture and lifetime comparable to the present SLS. Special operational modes are investigated to further explore the potential of the lattice. In this contribution, the first considerations on such modes for the SLS 2.0 are outlined. A promising high-brightness mode, increasing brightness by up to 25% at insertion devices with minor deterioration to dynamic and momentum aperture is presented. The use of round-beams and its impact on beam dynamics and the beamlines in the SLS 2.0 portfolio is discussed.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P26
About •	Received ※ 27 July 2023 — Revised ※ 24 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TU4P27	Progress of the HEPS Accelerator Construction and Linac Commissioning	131
	C. Meng, J.S. Cao, Z. Duan, D.Y. He, P. He, H.F. Ji, Y. Jiao, W. Kang, J. Li, J.Y. Li, W.M. Pan, Y.M. Peng, H. Qu, S.K. Tian, G. Xu, H.S. Xu, J. Zhang, J.R. Zhang IHEP, Beijing, People’s Republic of China X.H. Lu IHEP CSNS, Guangdong Province, People’s Republic of China
	The High Energy Photon Source (HEPS) is the first fourth-generation synchrotron radiation source in China that has been on the track for construction. The accelerator complex of the light source is composed of a 7BA storage ring, a booster injector, a Linac pre-injector, and three transfer lines. In order to provide high-bunch-charge beams for the storage ring, the booster was designed to be capable of both beam acceleration from low injection energy to extraction energy and charge accumulation at the extraction energy by means of accepting electron bunches from the storage ring. The Linac was built using S-band normal conducting structures, and can provide electron beam with pulse charge up to 7 nC. This paper reports the progress of the construction of the accelerators, including the installation of the storage ring, the pre-commissioning tests of the booster, and commissioning of the Linac. In particular, the beam commissioning of the Linac will be introduced in detail.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P27
About •	Received ※ 29 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P28	Useful Formulas and Example Parameters Set for the Design of SSMB Storage Rings	135
	X.J. Deng, A. Chao, W.-H. Huang, Z.Z. Li, Z. Pan, C.-X. Tang TUB, Beijing, People’s Republic of China
	A promising accelerator light source mechanism called steady-state microbunching (SSMB) has been actively studied in recent years. Here we summarize some important formulas for the design of SSMB storage rings. Generally we group our formulas into two categories, i.e., a longitudinal weak focusing storage ring for a desired radiation wavelength larger than 100 nm, and a transverse-longitudinal coupling, or a generalized longitudinal strong focusing, storage ring for a desired radiation wavelength between 1 nm and 100 nm. In each category, we have presented an example parameters set for the corresponding SSMB storage ring, to generate kW-level infrared, EUV and soft X-ray radiation, respectively.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P28
About •	Received ※ 15 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P29	Why is the Coherent Radiation from Laser-induced Microbunches Narrowbanded and Collimated	139
	X.J. Deng, A. Chao TUB, Beijing, People’s Republic of China
	There are two reasons: one is the long coherence length of radiation from micobunches imprinted by the modulation laser, the second is the finite transverse electron beam size. In other words, one is due to the longitudinal form factor, and the other the transverse form factor of the electron beam. Here we study the role of these form factors in shaping the energy spectrum and spatial distribution of microbunching radiation. The investigations are of value for cases like steady-state microbunching (SSMB), coherent harmonic generation (CHG) and free-electron laser (FEL).
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P29
About •	Received ※ 14 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P30	Optical Stochastic Cooling in a General Coupled Lattice	143
	X.J. Deng TUB, Beijing, People’s Republic of China
	Here we present a formalism of optical stochastic cooling in a 3D general coupled lattice. The formalism is general, and can treat a variety of damping and diffusion mechanisms within a single framework. We expect the work to be of value for the development of future light source.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P30
About •	Received ※ 15 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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WE4P18	Preliminary Design of Higher-order Achromat Lattice for the Upgrade of the Taiwan Photon Source	184
	N.Y. Huang, M.-S. Chiu, P.J. Chou, G.-H. Luo, H.W. Luo, H.-J. Tsai, F.H. Tseng NSRRC, Hsinchu, Taiwan
	We study the upgrade of Taiwan Photon Source (TPS) with energy saving as the prime objective. The upgrade design is dubbed TPS-II. To accommodate the constraints imposed by the existing TPS tunnel, we choose the higher-order achromat (HOA) lattice configuration which is composed of the 5BA and 4BA cells. This HOA lattice produces a natural beam emittance about 131 pm-rad for a 3 GeV, 518.4 m storage ring. The on-momentum dynamic aperture is about 8 mm and the estimated Touschek life time reaches around 5.7 hours at total beam current of 500 mA. As a result of the ultralow beam emittance, the brightness and coherence fraction (CF) of the photon beam are improved with a factor of several tens especially in the photon wavelength around 0.1 nm. The challenges and preliminary results of this HOA lattice design will be presented.
	Poster WE4P18 [5.398 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P18
About •	Received ※ 21 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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WE4P19	Simulation Study of Orbit Correction by Neural Network in Taiwan Photon Source	188
	M.-S. Chiu, Y.-S. Cheng, G.-H. Luo, H.-J. Tsai, F.H. Tseng NSRRC, Hsinchu, Taiwan C.P. Felix MCL/ITRI, Hsinchu, Taiwan
	Machine learning has been applied in many fields in re-cent decades. Many research articles also presented re-markable achievements in either operation or designing of the particle accelerator. This paper focuses on the simulated orbit correction by neural networks, a subset of machine learning, in Taiwan Photon Source. The training data for the neural network is generated by accelerator toolbox (AT).
	Poster WE4P19 [0.843 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P19
About •	Received ※ 23 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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WE4P20	Alignment Results of Tandem EPUs at the Taiwan Photon Source	192
	Y.-C. Liu, C.M. Cheng, T.Y. Chung, Y.M. Hsiao, F.H. Tseng NSRRC, Hsinchu, Taiwan
	Taiwan Photon Source (TPS) has been open to user operation since 2016. We report the alignment results of tandem EPUs in one double mini-beta y long straight section. The goal is to increase the brilliance of the synchrotron lights produced by the tandem EPUs through well-alignment and using a phase shifter to achieve both spatial and temporal coherence. The calculated brilliance gain of the tandem EPUs is compared, and the difference between the measured and numerical results is analyzed.
	Poster WE4P20 [4.435 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P20
About •	Received ※ 16 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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WE4P21	Some Beam Dynamic Issues in the HALF Storage Ring	196
	J.Y. Tang USTC, SNST, Anhui, People’s Republic of China Z.H. Bai, T.L. He, G. Liu, Y. Mo, A.X. Wang, P.H. Yang, Z. Zhao USTC/NSRL, Hefei, Anhui, People’s Republic of China
	HALF (Hefei Advanced Light Facility) is a fourth-generation synchrotron light source that just started construction in 2023. With 2.2 GeV in energy, 350 mA in beam current and 86 pm.rad in emittance, the HALF storage ring faces several beam dynamics challenges. This presentation gives the recent study on some of these issues, in particular the beam collimation and the influence and compensation of the insertion devices. For beam collimation, different beam loss mechanisms have been studied, and the Touschek scattering and beam dumping are considered the two major effects in designing the collimation system. Then two collimators with movable horizontal blades and fixed passive vertical blades are being designed, with the main focus on the collimation efficiency and impedance. For the influence of the insertion devices, it is found that some of the long-period undulators have a high impact on the beam dynamic aperture due to low beam energy and originally small dynamic aperture. The local compensation methods for both linear and non-linear effects have been studied. Instead of the traditional compensation method by electrical wires, the method of using two combined magnets with quadrupole and octupole fields at the two ID ends in restoring the dynamic aperture is also studied and compared.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P21
About •	Received ※ 23 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023
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WE4P24	Optics for an Electron Cooler for the EIC Based on an Electron Storage Ring	200
	J. Kewisch, A.V. Fedotov, X. Gu, Y.C. Jing, D. Kayran, I. Pinayev, S. Seletskiy BNL, Upton, New York, USA
	Funding: Supported by the US Department of Energy, Contract DE-SC0012704 An electron cooler based on a storage ring is one of the options to improve the luminosity in the Electron-Ion Collider (EIC). The transverse emittance of the electrons in the cooler is driven by the quantum excitation in dipoles and wigglers, as well as by both beam-beam scattering with the ions and intra-beam scattering of the electrons in the regions with a non-zero dispersion. The resulting demand to minimize a dispersion conflicts with the need of a sufficient dispersion in sextupoles for chromaticity correction. In this report we discuss our studies of several approaches to electron ring lattice, including those typically used in light sources, and present resulting compromise between various requirements.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P24
About •	Received ※ 23 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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WE4P31	Deterministic Approach to the Lattice Design of BESSY III	203
	B.C. Kuske, P. Goslawski HZB, Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association Since 2021 HZB pursues the design of a 2.5 GeV storage ring as a successor of BESSY II in Berlin. The user’s demand for diffraction-limited radiation at 1 keV corresponds to an emittance of 100 pm, making an MBA lattice indispensable. The envisaged location limits the circumference to ~350 m. MBA lattices are composed of smaller substructures that can be analyzed and optimized separately, before combining them into one super period. The prerequisite for this approach is a clear idea of the goal parameters and their prioritization, as the design process is dominated by permanent decisions between different options. The resulting generic baseline lattice for BESSY III is a simple structure with few non-linear elements, already fulfilling all goal parameters and showing a very compatible nonlinear behavior. This is our starting point for further optimizations including swarm or MOGA approaches.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P31
About •	Received ※ 30 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023
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TH3B1	Development of the In-vacuum APPLE II Undulators at HZB
	A. Meseck, J. Bahrdt, S. Gaebel, S. Gottschlich, S. Grimmer, C. Kuhn, F. Laube, E.C.M. Rial, M. Scheer, P.I. Volz HZB, Berlin, Germany
	HZB is working on a concept for BESSY III, the successor to BESSY II. It is planned to be a 4th generation synchrotron light source with an emittance of about 100 pm rad and an energy of 2.5 GeV. BESSY III will be equipped with advanced undulators to provide users with tailor-made light. Since polarisation control in the soft X-ray region is important for BESSY users, a variety of APPLE II undulators are planned, such as conventional (in-air), in-vacuum, cryogenic in-vacuum and double-period in-vacuum APPLE undulators (DoPUs). HZB has a long and successful tradition in the design, construction, and operation of conventional APPLE II devices. Currently, the first in-vacuum APPLE II undulator (IVUE32) is being built at HZB. In addition, the technical design of the cryogenic version of the In-Vacuum APPLE II (Cryo-APPLE) is progressing; construction will start at HZB in the next few years. This paper reports on the status of the In-Vacuum APPLE II and the Cryo-APPLE and outlines future development plans.
	Slides TH3B1 [6.205 MB]
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TH3B2	Novel X-ray Beam Position Monitor for Coherent Soft X-ray Beamlines	241
	B. Podobedov, D.M. Bacescu, C. Eng, S. Hulbert, C. Mazzoli, C.S. Nelson BNL, Upton, New York, USA D. Donetski, K. Kucharczyk, J. Liu, R. Lutchman, J. Zhao Stony Brook University, Stony Brook, New York, USA
	A novel soft X-ray BPM (sXBPM) for high-power white beams of synchrotron undulator radiation is being developed through a joint effort of BNL/NSLS-II and Stony Brook University. In our approach, custom-made multi-pixel GaAs detector arrays are placed into the outer portions of the X-ray beam, and the beam position is inferred from the pixel photocurrents. Our goal is to achieve micron-scale positional and ~50 nrad angular resolution without interfering with user experiments, especially the most sensitive ones exploiting coherent properties of the beam. To this end, an elaborate mechanical system has been designed, fabricated, and installed in the 23-ID canted undulator beamline first optical enclosure, which allows positioning of the detectors with micron-scale accuracy, and provisions for possible intercepts of kW-level beam in abnormal conditions. Separately, GaAs detectors with specially tailored spectral response have been designed, fabricated, and tested in the soft and hard X-ray regions at two NSLS-II beamlines. In this talk we plan to give an overview of the sXBPM system and present the first results from the high-power white X-ray beam.
	Slides TH3B2 [5.100 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH3B2
About •	Received ※ 15 September 2023 — Revised ※ 15 September 2023 — Accepted ※ 17 September 2023 — Issued ※ 02 December 2023
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TH3B3	Transverse Gradient Undulator for a Storage Ring X-Ray Free-Electron Laser Oscillator
	Y.S. Li University of Chicago, Chicago, Illinois, USA K.-J. Kim, R.R. Lindberg ANL, Lemont, Illinois, USA
	Funding: This work is supported by the U.S. Department of Energy, Office of Science under Contract No. DE-AC02-06CH11357 The X-ray free-electron laser oscillator (XFELO) has the potential to greatly surpass current SASE-FELs in terms of peak power and photon coherence. Although a large, 4th generation storage ring (4GSR) is promising as a diver for an XFELO operation, meeting the requisite electron energy spread remains a challenge. The transverse gradient undulator (TGU) is a potential solution to this issue. Using low-gain TGU theory, we derive optimal beam parameters for a hypothetical XFELO in a straight section of PETRA-IV and discuss potential implementation challenges associated with the ring-FEL coupling, namely FEL beam degradation and gain modulation. The need for a by-pass and fast kickers is obviated by equipping a higher charge (4 nC) to sixteen equidistant electron bunches for XFELO interaction. RF is used to control the FEL duty cycle and allow the XFELO bunches to damp before resuming the FEL interaction. Detailed multi-stage numerical simulation was used to compute the projected performance. T. I. Smith, L. R. Elias, J. M. J. Madey, and D. A. G. Deacon, J. Appl. Phys. 50, 4580 (1979). ** Y. S. Li, R. R. Lindberg, and K.-J. Kim, Phys. Rev. AB 26, p. 030702 (2023).
	Slides TH3B3 [3.213 MB]
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TH3B4	Generation of Multi X-Ray Pulses with Tunable Separation in Electron Storage Rings
	H.S. Xu, N. Wang, J.Y. Xu IHEP, Beijing, People’s Republic of China
	Synchrotron light sources, which can provide high brightness X-ray pulses to different users simultaneously, are demonstrated as a kind of very powerful tool for scientific research in many areas. Among the possible applications of synchrotron light sources, time resolved experiments are interesting for many users and usually require special operation modes. However, the time structures of X-ray pulses generated by a synchrotron light source are usually limited to integer times of the RF period, which is typically several nanoseconds (e.g., 2 ns RF period time corresponding to 500 MHz RF frequency). Here, we propose a novel scheme to take advantage of transverse deflecting cavities and over-stretching conditions of the higher harmonic cavities to ensure the transverse and longitudinal tunability of the twoμbunches in the same RF bucket. By applying this scheme, two X-ray pulses with tunable transverse displacement (mm level) and time delay (hundreds of ps level) can be provided to the scientific users for their X-ray pump X-ray probe experiments or X-ray probe X-ray probe experiments. The key setting parameters to generate the two X-ray pulses are given here. The classical "single-bunch" instabilities under the over-stretching conditions were also studied and presented.
	Slides TH3B4 [4.975 MB]
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FR1M2	Summary Report of Working Group B: Storage Ring Light Sources
	N. Carmignani ESRF, Grenoble, France M. Aiba PSI, Villigen PSI, Switzerland F.J. Cullinan MAX IV Laboratory, Lund University, Lund, Sweden A. Jankowiak HZB, Berlin, Germany S.C. Leemann LBNL, Berkeley, California, USA N. Yamamoto KEK, Ibaraki, Japan
	The paper highlights the key points arising from five insightful and instructive working group sessions.
	Slides FR1M2 [8.820 MB]
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Paper

Title

Page

MO2L1

Future of the Multi-bend Achromat

P. Raimondi
ESRF, Grenoble, France

The implementation of HMBA for upgrades of small and large scale rings will be described. A strategy to go toward a fully diffraction limited source based on HMBA, consistent with large dynamic aperture and long Toushek lifetime will also be presented.

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MO2L2

Storage Ring Based Steady State Microbunching

1

A. Chao
TUB, Beijing, People’s Republic of China

Powerful light sources are highly desired tools for scientific research and for industrial applications. Electrons are the objects that most readily and easily radiate photons. A natural conclusion follows that one should pursue electron accelerators as the choice tools towards powerful light sources. How to manipulate the electron beam in the accelerator so that it radiates light most efficiently, however, remains to be studied and its physical principle and technical limits be explored and optimized for the purpose. One such proposed concepts is based on the steady state microbunching (SSMB) mechanism in an electron storage ring. We make a brief introduction of the SSMB mechanism and its recent status in this presentation.

Slides MO2L2 [1.156 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO2L2

About •

Received ※ 25 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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MO2L3

Review of Harmonic Cavities in Fourth-generation Storage Rings

8

F.J. Cullinan, Å. Andersson, P. Tavares
MAX IV Laboratory, Lund University, Lund, Sweden

Several third generation light-source storage rings have used harmonic cavities to lengthen the electron bunches. With the advent of the fourth generation however, they have become an almost universal feature as the small transverse electron beam sizes make long bunches essential for increasing Touschek lifetime and reducing emittance blow-up from intrabeam scattering. Multiple technological solutions exist for the implementation of harmonic cavities and which to use remains an open question for many facilities. This is therefore a very active area of study in which there is strong collaboration within the community. Avoiding coherent collective beam instabilities is of particular concern. In this talk, I will summarise the results obtained so far. I will also give an overview of the observations made at the MAX IV 3 GeV ring, the first fourth generation storage ring which was commissioned with normal-conducting passive harmonic cavities already installed. Finally, I will discuss potential future directions.

Slides MO2L3 [3.035 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO2L3

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Received ※ 24 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 27 August 2023 — Issued ※ 02 December 2023

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MO3B1

Obtaining Picosecond X-ray Pulses on 4th Generation Synchrotron Light Sources

X. Huang, J.A. Safranek
SLAC, Menlo Park, California, USA
A. Zholents
ANL, Lemont, Illinois, USA

Through the 2-frequency crab cavity scheme, fourth generation storage ring light sources offer a unique opportunity to produce intense short X-ray pulses that are ideal for time-resolved user experiments. The short pulses and the high brightness photon beams are simultaneously available at all beamlines in a fully compatible operation mode. Owing to the small momentum compaction factor characteristic in fourth generation storage rings, the vertical emittance contribution due to the coupling between the longitudinal and transverse planes by the crab cavities is greatly reduced, which allows reaching short pulse duration with little constraint on the betatron tunes. We propose to use half-integer aharmonic cavity to simultaneously produce bunch lengthening and shortening in the bunch train to facilitate compatible operation of the normal and short-pulse beams. A concrete case study based on the Advanced Photon Source Upgrade (APS-U) lattice is used to demonstrate the system configuration, requirements, and beam performances.

Slides MO3B1 [1.817 MB]

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MO3B2

Beam Dynamics Using Superconducting Passive Harmonic Cavities with High Current per Bunch

14

A. Gamelin, V. Gubaidulin, A. Loulergue, P. Marchand, L.S. Nadolski, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France
N. Yamamoto
KEK, Ibaraki, Japan

In 4th generation synchrotron light sources, harmonic cavities (HCs) are critical components needed to achieve the required performance. They provide longer bunches, which helps to reduce statistical effects (intra-beam scattering and Touschek effect). In "timing" modes, where the bunch spacing is larger than in conventional modes and the number of particles per bunch is higher, this need is even greater. In this article, we present the beam dynamics in the high current per bunch regime and how it interacts with the single bunch collective effects. In particular, a dipole-quadrupole instability is observed above the microwave threshold and a coupling between the dipole and cavity modes is shown to limit bunch lengthening at low current. The effective gain from the use of HCs in terms of lifetime, emittance, and energy spread is also discussed.

Slides MO3B2 [1.529 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B2

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Received ※ 13 August 2023 — Revised ※ 15 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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MO3B3

Bunch-lengthening RF System Using Active Normal-conducting Cavities

18

N. Yamamoto, D. Naito, S. Sakanaka, T. Yamaguchi
KEK, Ibaraki, Japan
A. Gamelin, P. Marchand
SOLEIL, Gif-sur-Yvette, France

Bunch lengthening using a double RF system (fundamental + harmonic cavities) is essential in preserving the extremely low emittance in fourth and future generation synchrotron light rings. Recent studies have revealed that, in many cases, unstable beam motions, as so-called "mode-0" and "periodic transient beam loading" instabilities, prevent from reaching the optimum bunch lengthening condition with low and high beam current, respectively, even in symmetric filling patterns. While reducing the R/Q is beneficial for the latter, it will worsen the former. To achieve an efficient bunch lengthening system, we proposed a promising solution based on a powered TM020-type harmonic cavity with RF feedbacks (RF-FBs)*, as reported at FLS2018. Based on this concept, we are developing both fundamental and harmonic cavities using the TM020 resonant mode**, a kicker cavity having a bandwidth >5MHz***, bunch-phase monitor (BPhM) and RF-FBs. In this presentation, we describe our overall bunch lengthening system including cavity and BPhM designs. We also present particle tracking simulation results demonstrating that the bunch lengthening limitations can be alleviated by means of direct RF-FBs****.
* N. Yamamoto et al., PRAB 21, 012001, 2018.
** T. Yamaguchi et al., accepted in NIM A.
*** D. Naito et al, IPAC2021, MOPSB331, 2021.
**** N. Yamamoto et al., IPAC23, WEPL161, 2023.

Slides MO3B3 [2.655 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B3

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Received ※ 22 August 2023 — Revised ※ 23 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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MO3B4

Generating High Repetition Rate X-ray Attosecond Pulses in SAPS

22

W. Liu, X. Liu, Y. Zhao
IHEP CSNS, Guangdong Province, People’s Republic of China
Y. Jiao, X. Li, S. Wang
IHEP, Beijing, People’s Republic of China

Attosecond, which refers to 10^-18 seconds, is the timescale of electron motion within an atom. Accurate observation of electron motion helps deepen the understanding of microscopic quantum processes such as charge transfer in molecules, wave packet dynamics, and charge transfer in organic photovoltaic materials. To meet the needs of relevant research, the South Advanced Photon Source (SAPS), currently in the design phase, is considering the construction of an attosecond beamline. This paper presents relevant research on achieving high-repetition-rate coherent attosecond pulses on the fourth-generation storage ring at SAPS. Realizing attosecond pulses in a storage ring requires femtosecond to sub-femtosecond-level longitudinal modulation of the beam, and the modulation scheme needs to consider multiple factors to avoid a significant impact on other users. The study shows that with high-power, few-cycle lasers, and advanced beam modulation techniques, the photon flux of attosecond pulses can be significantly enhanced with a minimal impact on the brightness of synchrotron radiation. Adopting high-repetition-rate lasers and precise time delay control, the repetition rate of attosecond pulses at SAPS can reach the megahertz level. Currently, the design wavelength range for attosecond pulses covers the water window (2.3-4.4 nm), which is "transparent" to water but strongly absorbed by elements constituting living organisms. This wavelength range has significant application value in fields such as biology and chemistry.

Slides MO3B4 [3.400 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO3B4

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Received ※ 23 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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MO4B1

A Review on Injection Schemes

M. Aiba
PSI, Villigen PSI, Switzerland

Top-up injection into the storage ring is one of the main challenges of fourth generation light sources because of the limited machine aperture. Various new injection schemes have been studied over the past years, and are to be applied to newly constructed storage rings. There may not be single scheme that can be implemented into any storage ring due to the variety of specific needs and constraints. This talk presents an overview of the developments that may eventually help the storage ring designer to find the optimum scheme. The future trend of the top-up injection is also discussed.

Slides MO4B1 [1.306 MB]

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MO4B2

The Plasma Injector for PETRA IV: Conceptual Design Report

A. Martinez de la Ossa, I.V. Agapov, S.A. Antipov, R. Brinkmann, Á. Ferran Pousa, S. Jalas, M. Kirchen, W.P. Leemans, A.R. Maier, J. Osterhoff, R.J. Shalloo, M. Thévenet, P. Winkler
DESY, Hamburg, Germany

We present the conceptual design of an alternative injector system based on laser-plasma accelerator technology, to deliver high-quality electron bunches to PETRA IV - the future 4th generation synchrotron light source at DESY. The design consists of a laser-plasma accelerator to produce electron bunches at 6 GeV with state-of-the-art energy spread and stability, and a X-band energy compressor beamline to further reduce the overall beam energy deviations and maximize the charge injection throughput into the PETRA IV storage ring. Driven by the Petawatt upgrade of DESY’s new flagship laser KALDERA, the plasma injector system can be used to top up the PETRA IV storage ring, significantly lowering the load on the conventional injector chain. Ultimately, upon further development of high-efficiency, high-power laser drivers that operate at high repetition rates, the plasma injector could potentially replace the conventional system in the future and dramatically reduce the spatial footprint and energetic cost of the whole injector complex.

Slides MO4B2 [24.555 MB]

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MO4B3

Development of a Pulsed Injection Stripline for Diamond-II

38

R.T. Fielder, A. Lueangaramwong, A.F.D. Morgan
DLS, Oxfordshire, United Kingdom

Diamond-II will use a single bunch aperture sharing injection scheme. This applies a strong kick to both the injected and the targeted stored bunch with a very short duration (ideally <3 ns, if disturbance to the adjacent bunches is to be avoided). We have developed a design for the stripline kickers that can meet these requirements while minimising internal reflections and beam impedance. We show an analysis of the electric and magnetic fields produced by the stripline and simulations of the effects on injected and stored beam, and analysis of the wakefields and impedance of the structure.

Slides MO4B3 [2.164 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO4B3

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Received ※ 21 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU1B1

A Highly Competitive Non-Standard Lattice for a 4th Generation Light Source With Metrology and Timing Capabilities

58

P. Goslawski, M. Abo-Bakr, J. Bengtsson, K. Holldack, Z. Hüsges, A. Jankowiak, K. Kiefer, B.C. Kuske, A. Meseck, R. Müller, M.K. Sauerborn, O. Schwarzkopf, J. Viefhaus, J. Völker
HZB, Berlin, Germany

The PTB, Germany’s national institute for standards and metrology, has relied on synchrotron radiation for metrology purposes for over 40 years and the most prominent customers are lithography systems from ASML/ZEIS. HZB is now working on a concept for a BESSY II successor, based on a 4th generation light source with an emittance of 100 pmrad @ 2.5 GeV. It is essential, that this new facility continues to serve the PTB for metrology purposes. This sets clear boundary conditions for the lattice design, in particular, the need for homogeneous bends as metrological radiation sources. Different Higher-Order-Multi-Bend-Achromat lattices have been developed, based on combined function gradient bends and homogeneous bends in a systematic lattice design approach. All lattices are linearly equivalent with the same emittance and maximum field strength. However, they differ significantly in their non-linear behavior. Based on this analysis, the choice of the BESSY III lattice type is motivated. A special focus is set also on TRIBs (Transverse Resonance Island Buckets) to operate with two orbits as a bunch separation scheme in MBAs, for different repetition rates or for the separation of short and long bunches.

Slides TU1B1 [7.584 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1B1

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Received ※ 23 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU1B2

Low-alpha Storage Ring Design for Steady-State Microbunching to Generate EUV Radiation

Z. Pan, A. Chao, X.J. Deng, W.-H. Huang, R.K. Li, Z.Z. Li, C.-X. Tang
TUB, Beijing, People’s Republic of China

A new concept is proposed for minimizing the longitudinal emittance of a low momentum compaction factor (low-alpha) storage ring which has the capability to stably store sub-femtosecond electron bunches for the first time. This storage ring is designed for Steady-State microbunching (SSMB) to generate kW level average power EUV radiation. The proposed design approach can be applied to any quasi-isochronous storage rings to yield very high radiation power due to longitudinal coherence of the radiation. We obtain an optimal lattice design by minimizing global and local momentum compaction factors simultaneously and the result of single-particle tracking shows that the electron beam with equilibrium rms bunch length of about 40 nm can be stored in this ring. We also clarify in this type ring, the horizontal emittance will be fixed when beam energy, dipole bending angle and cell tune is fixed. In this type ring, the calculation for IBS effect will be different with traditional rings, we point out where the difference is and give a more convenient calculation for it.

Slides TU1B2 [1.628 MB]

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TU1B3

Nonlinear Optics From Hybrid Dispersive Orbits

62

Y. Li, R.S. Rainer, V.V. Smaluk, D. Xu
BNL, Upton, New York, USA

Funding: Supported by US DoE under Contract No. DE-SC0012704
In this paper we present an expansion of the technique of characterizing nonlinear optics from off-energy orbits (NOECO) to cover harmonic sextupoles in storage rings. The existing NOECO technique has been successfully used to correct the chromatic sextupole errors on the MAX-IV machine, however, it did not account for harmonic sextupoles, which are widely used on many other machines. Through generating vertical dispersion with chromatic skew quadrupoles, a measurable dependence of nonlinear optics on harmonic sextupoles can be observed from hybrid horizontal and vertical dispersive orbits. Proof of concept of our expanded technique was accomplished by simulations and beam measurements on the National Synchrotron Light Source II (NSLS-II) storage ring.

Slides TU1B3 [1.428 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1B3

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Received ※ 18 August 2023 — Revised ※ 20 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TU1B4

Minimizing the Fluctuation of Resonance Driving Terms for Analyzing and Optimizing the Storage Ring Dynamic Aperture

66

Z.H. Bai, B.F. Wei
USTC/NSRL, Hefei, Anhui, People’s Republic of China
A. Loulergue, L.S. Nadolski, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

Minimization of resonance driving terms (RDTs) of nonlinear magnets such as sextupoles and octupoles is an essential condition for enlarging the dynamic aperture (DA) of a storage ring. We recently studied the correlation between minimizing the fluctuation or variation of RDTs along the ring and enlarging the DA. It was found that minimizing the RDT fluctuations is much more effective than minimizing the commonly-used one-turn RDTs in enlarging the DA, and that reducing low-order RDT fluctuations can also help reduce both higher-order RDT fluctuations and higher-order one-turn RDTs. In this paper, DA analysis based on minimizing RDT fluctuations is further extended. By considering the RDT fluctuations including low- and high-frequency fluctuations, some nonlinear dynamics issues can be explained. DA optimization is also studied based on numerically minimizing RDT fluctuations using genetic algorithms. Large DA can be obtained, and the optimization is performed very fast.

Slides TU1B4 [3.118 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1B4

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Received ※ 23 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU3B1

Machine Learning Applications for Performance Improvement and Developing Future Storage Ring Light Sources

S.C. Leemann
LBNL, Berkeley, USA

Funding: This research is funded by the US Department of Energy (BES & ASCR Programs), and supported by the Director of the Office of Science of the US Department of Energy under Contract No. DEAC02-05CH11231.
This presentation will focus on two recent applications of Machine Learning (ML) to storage ring-based synchrotron light sources. The first example highlights improvement of storage ring performance by use of ML to stabilize the electron beam size at the source points against perturbations from insertion device (ID) motion*. The stability of the source size is improved by roughly one order of magnitude through a neural network-based feed-forward that compensates, in a model-independent manner, for ID-induced source size changes before they can occur. In the second example, ML is used to replace many-turn particle tracking in multi-objective genetic algorithms (MOGA) for the design of lattices for demanding future storage rings**. By training neural networks to give accurate predictions of nonlinear lattice properties such as dynamic aperture and momentum aperture, the overall MOGA optimization process an be substantially accelerated. Including overhead from training and iterative retraining, MOGA optimization can be accelerated through ML by up to two orders of magnitude, thereby dropping overall optimization campaign runtime even on large clusters from weeks to just hours.
* Phys. Rev. Lett. 123, 194801 (2019), https://doi.org/10.1103/PhysRevLett.123.194801
** Nucl. Instrum. Methods Phys. Res., A 1050, 168192 (2023), https://doi.org/10.1016/j.nima.2023.168192

Slides TU3B1 [35.589 MB]

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TU3B2

Recent Developments of the Toolkit for Simulated Commissioning

T. Hellert
LBNL, Berkeley, California, USA

Detailed commissioning simulations have become the main tool of error analysis during lattice design of 4th generation storage ring light sources in recent years. The Matlab based Toolkit for Simulated Commissioning provides a high fidelity error model and a user friendly interface and is currently used at several facilities around the world. This contribution will present the toolkit with the highlight on recent developments such as the integration into the ALS control system for automated startup procedures and the transcription into python, enabling large scale parallelization.

Slides TU3B2 [45.870 MB]

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TU3B3

Pyapas: A New Framework for High Level Application Development at HEPS

77

X.H. Lu
IHEP CSNS, Guangdong Province, People’s Republic of China
D. Ji, H.F. Ji, Y. Jiao, J.Y. Li, N. Li, C. Meng, Y.M. Peng, J. Wan, Y. Wei, G. Xu, H.S. Xu, Y.L. Zhao
IHEP, Beijing, People’s Republic of China

The development of high-level application (HLA) is an indispensable part of the light source construction process. With the increase in the scale and complexity of accelerators, the development of HLA will also face many new challenges, such as increased data volume, multiple data types, more parameter channels, and more complex tuning algorithms. So a new framework named Pyapas has been designed for HLA development which aims to provide a high-performance, scalable, flexible, and reliable HLA development framework to meet the needs of large-scale parameter tuning and data processing. Pyapas is designed with a modular concept, decomposing the development needs of HLA into different modules for decoupled development, and calling them through simple interfaces. In the communication module, a singleton factory class is designed to avoid duplicate creation of channel connections, and combined with Qt’s signal-slot mechanism to create non-blocking communication connections, greatly improving the carrying capacity of parameter scale. While a deeply decoupled two-layer physical model module is designed to quickly switch different mathematical models to meet different online computing needs. Moreover, the design of the C/S architecture development module and the rapid creation and management module of the database is helpful for quickly developing complex programs, further enhancing the applicability of Pyapas. This paper will introduce the main feature of Pyapas

Slides TU3B3 [6.913 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU3B3

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Received ※ 30 August 2023 — Revised ※ 31 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023

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TU3B4

Use of Automated Commissioning Simulations for Error Tolerance Evaluation for the Advanced Photon Source Upgrade

V. Sajaev, M. Borland
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Multi-bend achromat-based light source designs are known to have rather strong focusing and rather small vacuum chambers, which pretty much guarantees difficult commissioning. To ensure the Advanced Photon Source Upgrade* commissioning is possible, the automated commissioning simulations were developed**. The simulations start from trajectory correction in the transport line, go through first-turn correction, trajectory and orbit correction, and complete with lattice and coupling correction. In addition to ensuring smooth commissioning, these simulations proved very useful in evaluating error tolerances under the most realistic conditions. In some cases, this approach allows for significant relaxation of the tolerances. We will describe APS-U automated commissioning simulations and give examples of error tolerance evaluations.
*M. Borland et al., "The Upgrade of the Advanced Photon Source", in Proc. IPAC’18, Vancouver, Canada, Apr.-May 2018, pp. 2872-2877
**V.Sajaev, "Commissioning simulations for the aps upgrade lattice," Phys. Rev. Accel. Beams, vol. 22, p. 040102, 2019

Slides TU3B4 [5.581 MB]

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TU4P17

Non-destructive Vertical Halo-monitors on the ESRF Electron Beam

112

K.B. Scheidt
ESRF, Grenoble, France

The ESRF EBS storage ring has since spring 2022 among its electron beam diagnostics two independent units of vertical Halo-monitors. The principle and the components of this unique diagnostic will be explained in details. It uses the available X-rays in a non-used Front-End, emitted from a 0.57 T standard dipole magnet in the EBS lattice. This instrument measures the so-called "far-away" Halo level, i.e. in a zone of roughly 1-3 mm away from the beam centre, which represents 200-600 times the electron’s vertical beam-size, supposedly Gaussian, of 5 um. It is measured, and expressed quantitively in picoAmp beam current, at 1 Hz rate. Both units are yielding very satisfying and well-correlated results that will be presented in details, and in relation with studies on the electron beam and the accelerator components like variation of current, filling-patterns, vertical emittance, quality of the vacuum, settings of the undulator gaps, collimators, scrapers etc. and also in direct correlation with measurements of our 128 beamloss detectors and beam lifetime.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P17

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Received ※ 21 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P18

Nonlinear Dynamics Measurements at the EBS Storage Ring

116

N. Carmignani, L.R. Carver, L. Hoummi, S.M. Liuzzo, T.P. Perron, S.M. White
ESRF, Grenoble, France

The EBS is a 4th generation synchrotron light source and it has been in user operation since August 2020 at the ESRF. Several measurements to characterise the nonlinear dynamics have been performed in 2023: nonlinear chromaticity, second order dispersion and detuning with amplitude. The results of the measurements are shown and compared with simulations.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P18

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Received ※ 23 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P19

Evolution of Equilibrium Parameters Ramp Including Collective Effects in the Diamond-II Booster

120

R. Husain, R.T. Fielder, I.P.S. Martin
DLS, Oxfordshire, United Kingdom
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

Efficient top-up injection into the Diamond-II storage ring will require upgrading the booster lattice for a beam emittance of <20 nm rad and a bunch length of <40 ps, including when operating with high single-bunch charge. The small vacuum chamber dimensions will drive the resistive wall instability and may adversely affect equilibrium parameters along the beam energy ramp. In addition, various diagnostic and vacuum chamber components will generate geometric impedances which may further disrupt the equilibrium parameters. Based on the detailed engineering designs, impedance models of the major components have been simulated using CST Studio and included in ELEGANT tracking simulations of the booster. In addition, the effects of synchrotron radiation emission and intra-beam scattering on the equilibrium parameters during the ramp are studied.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P19

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Received ※ 22 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P20

Simulated Commissioning for Diamond-II Storage Ring from On-axis to Off-axis Injection

124

H.-C. Chao, I.P.S. Martin
DLS, Oxfordshire, United Kingdom

The Diamond-II storage ring commissioning simulations have continued based on the previous results where on-axis injected beams are captured. The next goal is to enlarge the dynamic aperture so that off-axis injection can be achieved. The procedures include beam based alignment, beta-beating correction and linear optics correction. Details of the implementations are discussed and the simulation results are presented. In the end, we are able to reach off-axis injection which allows accumulation.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P20

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Received ※ 22 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TU4P26

Special Operational Modes for SLS 2.0

127

J. Kallestrup, M. Aiba
PSI, Villigen PSI, Switzerland

The SLS 2.0 storage ring will achieve low emittance and high brightness while maintaining large dynamic aperture and lifetime comparable to the present SLS. Special operational modes are investigated to further explore the potential of the lattice. In this contribution, the first considerations on such modes for the SLS 2.0 are outlined. A promising high-brightness mode, increasing brightness by up to 25% at insertion devices with minor deterioration to dynamic and momentum aperture is presented. The use of round-beams and its impact on beam dynamics and the beamlines in the SLS 2.0 portfolio is discussed.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P26

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Received ※ 27 July 2023 — Revised ※ 24 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TU4P27

Progress of the HEPS Accelerator Construction and Linac Commissioning

131

C. Meng, J.S. Cao, Z. Duan, D.Y. He, P. He, H.F. Ji, Y. Jiao, W. Kang, J. Li, J.Y. Li, W.M. Pan, Y.M. Peng, H. Qu, S.K. Tian, G. Xu, H.S. Xu, J. Zhang, J.R. Zhang
IHEP, Beijing, People’s Republic of China
X.H. Lu
IHEP CSNS, Guangdong Province, People’s Republic of China

The High Energy Photon Source (HEPS) is the first fourth-generation synchrotron radiation source in China that has been on the track for construction. The accelerator complex of the light source is composed of a 7BA storage ring, a booster injector, a Linac pre-injector, and three transfer lines. In order to provide high-bunch-charge beams for the storage ring, the booster was designed to be capable of both beam acceleration from low injection energy to extraction energy and charge accumulation at the extraction energy by means of accepting electron bunches from the storage ring. The Linac was built using S-band normal conducting structures, and can provide electron beam with pulse charge up to 7 nC. This paper reports the progress of the construction of the accelerators, including the installation of the storage ring, the pre-commissioning tests of the booster, and commissioning of the Linac. In particular, the beam commissioning of the Linac will be introduced in detail.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P27

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Received ※ 29 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P28

Useful Formulas and Example Parameters Set for the Design of SSMB Storage Rings

135

X.J. Deng, A. Chao, W.-H. Huang, Z.Z. Li, Z. Pan, C.-X. Tang
TUB, Beijing, People’s Republic of China

A promising accelerator light source mechanism called steady-state microbunching (SSMB) has been actively studied in recent years. Here we summarize some important formulas for the design of SSMB storage rings. Generally we group our formulas into two categories, i.e., a longitudinal weak focusing storage ring for a desired radiation wavelength larger than 100 nm, and a transverse-longitudinal coupling, or a generalized longitudinal strong focusing, storage ring for a desired radiation wavelength between 1 nm and 100 nm. In each category, we have presented an example parameters set for the corresponding SSMB storage ring, to generate kW-level infrared, EUV and soft X-ray radiation, respectively.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P28

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Received ※ 15 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P29

Why is the Coherent Radiation from Laser-induced Microbunches Narrowbanded and Collimated

139

X.J. Deng, A. Chao
TUB, Beijing, People’s Republic of China

There are two reasons: one is the long coherence length of radiation from micobunches imprinted by the modulation laser, the second is the finite transverse electron beam size. In other words, one is due to the longitudinal form factor, and the other the transverse form factor of the electron beam. Here we study the role of these form factors in shaping the energy spectrum and spatial distribution of microbunching radiation. The investigations are of value for cases like steady-state microbunching (SSMB), coherent harmonic generation (CHG) and free-electron laser (FEL).

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P29

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Received ※ 14 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P30

Optical Stochastic Cooling in a General Coupled Lattice

143

X.J. Deng
TUB, Beijing, People’s Republic of China

Here we present a formalism of optical stochastic cooling in a 3D general coupled lattice. The formalism is general, and can treat a variety of damping and diffusion mechanisms within a single framework. We expect the work to be of value for the development of future light source.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P30

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Received ※ 15 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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WE4P18

Preliminary Design of Higher-order Achromat Lattice for the Upgrade of the Taiwan Photon Source

184

N.Y. Huang, M.-S. Chiu, P.J. Chou, G.-H. Luo, H.W. Luo, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan

We study the upgrade of Taiwan Photon Source (TPS) with energy saving as the prime objective. The upgrade design is dubbed TPS-II. To accommodate the constraints imposed by the existing TPS tunnel, we choose the higher-order achromat (HOA) lattice configuration which is composed of the 5BA and 4BA cells. This HOA lattice produces a natural beam emittance about 131 pm-rad for a 3 GeV, 518.4 m storage ring. The on-momentum dynamic aperture is about 8 mm and the estimated Touschek life time reaches around 5.7 hours at total beam current of 500 mA. As a result of the ultralow beam emittance, the brightness and coherence fraction (CF) of the photon beam are improved with a factor of several tens especially in the photon wavelength around 0.1 nm. The challenges and preliminary results of this HOA lattice design will be presented.

Poster WE4P18 [5.398 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P18

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Received ※ 21 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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WE4P19

Simulation Study of Orbit Correction by Neural Network in Taiwan Photon Source

188

M.-S. Chiu, Y.-S. Cheng, G.-H. Luo, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan
C.P. Felix
MCL/ITRI, Hsinchu, Taiwan

Machine learning has been applied in many fields in re-cent decades. Many research articles also presented re-markable achievements in either operation or designing of the particle accelerator. This paper focuses on the simulated orbit correction by neural networks, a subset of machine learning, in Taiwan Photon Source. The training data for the neural network is generated by accelerator toolbox (AT).

Poster WE4P19 [0.843 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P19

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Received ※ 23 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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WE4P20

Alignment Results of Tandem EPUs at the Taiwan Photon Source

192

Y.-C. Liu, C.M. Cheng, T.Y. Chung, Y.M. Hsiao, F.H. Tseng
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) has been open to user operation since 2016. We report the alignment results of tandem EPUs in one double mini-beta y long straight section. The goal is to increase the brilliance of the synchrotron lights produced by the tandem EPUs through well-alignment and using a phase shifter to achieve both spatial and temporal coherence. The calculated brilliance gain of the tandem EPUs is compared, and the difference between the measured and numerical results is analyzed.

Poster WE4P20 [4.435 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P20

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Received ※ 16 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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WE4P21

Some Beam Dynamic Issues in the HALF Storage Ring

196

J.Y. Tang
USTC, SNST, Anhui, People’s Republic of China
Z.H. Bai, T.L. He, G. Liu, Y. Mo, A.X. Wang, P.H. Yang, Z. Zhao
USTC/NSRL, Hefei, Anhui, People’s Republic of China

HALF (Hefei Advanced Light Facility) is a fourth-generation synchrotron light source that just started construction in 2023. With 2.2 GeV in energy, 350 mA in beam current and 86 pm.rad in emittance, the HALF storage ring faces several beam dynamics challenges. This presentation gives the recent study on some of these issues, in particular the beam collimation and the influence and compensation of the insertion devices. For beam collimation, different beam loss mechanisms have been studied, and the Touschek scattering and beam dumping are considered the two major effects in designing the collimation system. Then two collimators with movable horizontal blades and fixed passive vertical blades are being designed, with the main focus on the collimation efficiency and impedance. For the influence of the insertion devices, it is found that some of the long-period undulators have a high impact on the beam dynamic aperture due to low beam energy and originally small dynamic aperture. The local compensation methods for both linear and non-linear effects have been studied. Instead of the traditional compensation method by electrical wires, the method of using two combined magnets with quadrupole and octupole fields at the two ID ends in restoring the dynamic aperture is also studied and compared.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P21

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Received ※ 23 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023

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WE4P24

Optics for an Electron Cooler for the EIC Based on an Electron Storage Ring

200

J. Kewisch, A.V. Fedotov, X. Gu, Y.C. Jing, D. Kayran, I. Pinayev, S. Seletskiy
BNL, Upton, New York, USA

Funding: Supported by the US Department of Energy, Contract DE-SC0012704
An electron cooler based on a storage ring is one of the options to improve the luminosity in the Electron-Ion Collider (EIC). The transverse emittance of the electrons in the cooler is driven by the quantum excitation in dipoles and wigglers, as well as by both beam-beam scattering with the ions and intra-beam scattering of the electrons in the regions with a non-zero dispersion. The resulting demand to minimize a dispersion conflicts with the need of a sufficient dispersion in sextupoles for chromaticity correction. In this report we discuss our studies of several approaches to electron ring lattice, including those typically used in light sources, and present resulting compromise between various requirements.

DOI •

reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P24

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Received ※ 23 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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WE4P31

Deterministic Approach to the Lattice Design of BESSY III

203

B.C. Kuske, P. Goslawski
HZB, Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association
Since 2021 HZB pursues the design of a 2.5 GeV storage ring as a successor of BESSY II in Berlin. The user’s demand for diffraction-limited radiation at 1 keV corresponds to an emittance of 100 pm, making an MBA lattice indispensable. The envisaged location limits the circumference to ~350 m. MBA lattices are composed of smaller substructures that can be analyzed and optimized separately, before combining them into one super period. The prerequisite for this approach is a clear idea of the goal parameters and their prioritization, as the design process is dominated by permanent decisions between different options. The resulting generic baseline lattice for BESSY III is a simple structure with few non-linear elements, already fulfilling all goal parameters and showing a very compatible nonlinear behavior. This is our starting point for further optimizations including swarm or MOGA approaches.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-WE4P31

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Received ※ 30 August 2023 — Revised ※ 30 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023

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TH3B1

Development of the In-vacuum APPLE II Undulators at HZB

A. Meseck, J. Bahrdt, S. Gaebel, S. Gottschlich, S. Grimmer, C. Kuhn, F. Laube, E.C.M. Rial, M. Scheer, P.I. Volz
HZB, Berlin, Germany

HZB is working on a concept for BESSY III, the successor to BESSY II. It is planned to be a 4th generation synchrotron light source with an emittance of about 100 pm rad and an energy of 2.5 GeV. BESSY III will be equipped with advanced undulators to provide users with tailor-made light. Since polarisation control in the soft X-ray region is important for BESSY users, a variety of APPLE II undulators are planned, such as conventional (in-air), in-vacuum, cryogenic in-vacuum and double-period in-vacuum APPLE undulators (DoPUs). HZB has a long and successful tradition in the design, construction, and operation of conventional APPLE II devices. Currently, the first in-vacuum APPLE II undulator (IVUE32) is being built at HZB. In addition, the technical design of the cryogenic version of the In-Vacuum APPLE II (Cryo-APPLE) is progressing; construction will start at HZB in the next few years. This paper reports on the status of the In-Vacuum APPLE II and the Cryo-APPLE and outlines future development plans.

Slides TH3B1 [6.205 MB]

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TH3B2

Novel X-ray Beam Position Monitor for Coherent Soft X-ray Beamlines

241

B. Podobedov, D.M. Bacescu, C. Eng, S. Hulbert, C. Mazzoli, C.S. Nelson
BNL, Upton, New York, USA
D. Donetski, K. Kucharczyk, J. Liu, R. Lutchman, J. Zhao
Stony Brook University, Stony Brook, New York, USA

A novel soft X-ray BPM (sXBPM) for high-power white beams of synchrotron undulator radiation is being developed through a joint effort of BNL/NSLS-II and Stony Brook University. In our approach, custom-made multi-pixel GaAs detector arrays are placed into the outer portions of the X-ray beam, and the beam position is inferred from the pixel photocurrents. Our goal is to achieve micron-scale positional and ~50 nrad angular resolution without interfering with user experiments, especially the most sensitive ones exploiting coherent properties of the beam. To this end, an elaborate mechanical system has been designed, fabricated, and installed in the 23-ID canted undulator beamline first optical enclosure, which allows positioning of the detectors with micron-scale accuracy, and provisions for possible intercepts of kW-level beam in abnormal conditions. Separately, GaAs detectors with specially tailored spectral response have been designed, fabricated, and tested in the soft and hard X-ray regions at two NSLS-II beamlines. In this talk we plan to give an overview of the sXBPM system and present the first results from the high-power white X-ray beam.

Slides TH3B2 [5.100 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH3B2

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Received ※ 15 September 2023 — Revised ※ 15 September 2023 — Accepted ※ 17 September 2023 — Issued ※ 02 December 2023

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TH3B3

Transverse Gradient Undulator for a Storage Ring X-Ray Free-Electron Laser Oscillator

Y.S. Li
University of Chicago, Chicago, Illinois, USA
K.-J. Kim, R.R. Lindberg
ANL, Lemont, Illinois, USA

Funding: This work is supported by the U.S. Department of Energy, Office of Science under Contract No. DE-AC02-06CH11357
The X-ray free-electron laser oscillator (XFELO) has the potential to greatly surpass current SASE-FELs in terms of peak power and photon coherence. Although a large, 4th generation storage ring (4GSR) is promising as a diver for an XFELO operation, meeting the requisite electron energy spread remains a challenge. The transverse gradient undulator (TGU) is a potential solution to this issue*. Using low-gain TGU theory, we derive optimal beam parameters for a hypothetical XFELO in a straight section of PETRA-IV and discuss potential implementation challenges associated with the ring-FEL coupling, namely FEL beam degradation and gain modulation. The need for a by-pass and fast kickers is obviated by equipping a higher charge (4 nC) to sixteen equidistant electron bunches for XFELO interaction. RF is used to control the FEL duty cycle and allow the XFELO bunches to damp before resuming the FEL interaction. Detailed multi-stage numerical simulation was used to compute the projected performance**.
* T. I. Smith, L. R. Elias, J. M. J. Madey, and D. A. G. Deacon, J. Appl. Phys. 50, 4580 (1979).
** Y. S. Li, R. R. Lindberg, and K.-J. Kim, Phys. Rev. AB 26, p. 030702 (2023).

Slides TH3B3 [3.213 MB]

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TH3B4

Generation of Multi X-Ray Pulses with Tunable Separation in Electron Storage Rings

H.S. Xu, N. Wang, J.Y. Xu
IHEP, Beijing, People’s Republic of China

Synchrotron light sources, which can provide high brightness X-ray pulses to different users simultaneously, are demonstrated as a kind of very powerful tool for scientific research in many areas. Among the possible applications of synchrotron light sources, time resolved experiments are interesting for many users and usually require special operation modes. However, the time structures of X-ray pulses generated by a synchrotron light source are usually limited to integer times of the RF period, which is typically several nanoseconds (e.g., 2 ns RF period time corresponding to 500 MHz RF frequency). Here, we propose a novel scheme to take advantage of transverse deflecting cavities and over-stretching conditions of the higher harmonic cavities to ensure the transverse and longitudinal tunability of the twoμbunches in the same RF bucket. By applying this scheme, two X-ray pulses with tunable transverse displacement (mm level) and time delay (hundreds of ps level) can be provided to the scientific users for their X-ray pump X-ray probe experiments or X-ray probe X-ray probe experiments. The key setting parameters to generate the two X-ray pulses are given here. The classical "single-bunch" instabilities under the over-stretching conditions were also studied and presented.

Slides TH3B4 [4.975 MB]

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FR1M2

Summary Report of Working Group B: Storage Ring Light Sources

N. Carmignani
ESRF, Grenoble, France
M. Aiba
PSI, Villigen PSI, Switzerland
F.J. Cullinan
MAX IV Laboratory, Lund University, Lund, Sweden
A. Jankowiak
HZB, Berlin, Germany
S.C. Leemann
LBNL, Berkeley, California, USA
N. Yamamoto
KEK, Ibaraki, Japan

The paper highlights the key points arising from five insightful and instructive working group sessions.

Slides FR1M2 [8.820 MB]

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