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TU3D1 |
Developments in SRF Technology for Light Source Applications |
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- D. Gonnella
SLAC, Menlo Park, California, USA
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Funding: US DoE
Significant developments in SRF technology have occurred in the last 5 years motivated by interest in light sources and future colliders. Specifically, LCLS-II and LCLS-II-HE at SLAC have driven high gradient and high Q₀ R&D in SRF across the field. New understandings in doping protocols, cavity processing, and clean room procedures have enabled cryomodules to be constructed that reach previously unattainable performance. Further developments in novel cavity processing methods such as mid-temperature baking and alternate materials such as niobium-3-tin enable a new range of operations for future accelerators. Early operations from LCLS-II and EU-XFEL show that SRF technology is already being used to produce world class light source facilities. Here we present a review of the latest developments in SRF technology both in the R&D phase and in newly installed accelerators and their impact on future light source development and performance.
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Slides TU3D1 [5.769 MB]
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TU3D2 |
Highly Reliable RF Power Sources for Improvement of the Accelerator Availability |
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- M. Lau
TRUMPF Huettinger GmbH, Freiburg, Germany
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The trend in exchanging established tube technolo-gy by solid-state based RF power amplifier for particle accelerators around the world is ongoing. Since the first installations* of such amplifier systems several concepts were developed and installed**. As the RF sources are key for the accelerator availability their reliability plays a crucial role. This needs to be considered during the design phase of the overall amplifier system architecture in a new way compared to the tube technology. For tubes it is straight forward as usually one tube powers one or more cavities due to the high power provided. But this also bears the risk of a single point of failure despite the need of high voltage power supplies, continuous degradation and their availability, just to mention the most important aspects. For solid-state power amplifier many transistor units need to be combined for delivering the needed RF power to each cavity. The combining concepts and the overall system architecture finally determine the possibility of de-rating options and redundancy of transistors for compensation of failed units within the system, and thus the overall availability. Our concept for com-bining several transistors in amplifier units*** and assembling these units into racks recently has proven an outstanding performance. For 8,419 hours of opera-tional time, we had a total of 13.9 hours for not being available due to incidents. This results in a total system availability of ~99.83% for more than 980 operational amplifier units at customer site. Here, we want to demonstrate our system architec-ture and the design aspects we considered for reaching this high performance. We think that this is a crucial contribution for bringing this technology one step further to maturity.
* R. Lopes et al., CWRF08, CERN Geneva, March 2008
** E. Montesinos, I.FAST Accelerator-Industry Workshop, CERN, May, 2022
*** M. Lau et al., HIAT Conference, Darmstadt, Germany, 2022
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Slides TU3D2 [5.323 MB]
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TU3D3 |
Application of Cryo-copper Accelerating Structures Towards Future Light Sources |
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- E.A. Nanni
SLAC, Menlo Park, California, USA
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Cryogenic operation of copper accelerating structures results in increase accelerating gradients and reduced rf power requirements. The combination of cryogenic operation with distributed coupling accelerator topologies further enhances the flexibility of the designer in optimizing the performance of the accelerator. The combination of these advances creates the possibility of generating high-brightness beams in compact footprints (up to 250 MeV/m accelerating gradients). To date this technology has been explored primarily in the context of a future high energy physics facility. In this talk we will present the study of a new concept for a high gradient, high power accelerator with beam characteristics suitable to study the Higgs boson, the Cool Copper Collider (C3). We will present the latest demonstrated performance of prototype accelerators and highlight the future development path for C3 accelerator technology. In particular, we will focus on benefits to future light source concepts to decrease machine size, increase repetition rate, enable multi-bunch operation and preserve high brightness beams. Possible use cases for future light sources will be presented.
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Slides TU3D3 [6.783 MB]
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| TU3D4 |
Compact HOM-damped RF Cavity for a Next Generation Light Source |
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- H. Ego
KEK, Ibaraki, Japan
- T. Asaka, N. Nishimori
QST, Sendai, Miyagi, Japan
- T. Inagaki, H. Tanaka
RIKEN SPring-8 Center, Hyogo, Japan
- T. Ohshima, T. Tomai, H. Yamaguchi
JASRI, Hyogo, Japan
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A beam-accelerating RF cavity with a new HOM-damping structure was designed in order to suppress coupled-bunch instabilities in a next generation light source with an ultra-low emittance and supplying X-rays approaching their diffraction limits. The TM020 mode at 509 MHz is selected as a beam-accelerating mode because it has a high Q-value of 60,000 and a shunt impedance sufficient for beam acceleration and brings a compact HOM-damping structure to the cavity differently from massive types of cavities with waveguides or pipes extracting HOM power. Two shallow slots are cut on the cavity inner-wall and materials absorbing RF waves are directly fitted into them. They work as HOM dampers without affecting the RF properties of the beam-accelerating mode. A prototype cavity of OFHC copper was fabricated to demonstrate the HOM-damping and generating an accelerating voltage of 900 kV in the cavity. Since the cavity was successful in operation up to 135 kW, the feasibility of both the high-power operation and the damping structure was proved. Four actual cavities were produced and installed to the new 3-GeV synchrotron radiation facility, NanoTerasu in Japan.
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Slides TU3D4 [8.581 MB]
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| DOI • |
reference for this paper
※ doi:10.18429/JACoW-FLS2023-TU3D4
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| About • |
Received ※ 22 August 2023 — Revised ※ 23 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023 |
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TU3D5 |
Electron RF Injectors for Next Generation FELs |
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- B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
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A modern trend in the next generation of X-ray Free Electron Lasers (FEL) is the development of tools for the investigation of dynamic processes on the (sub)atomic scale that requires photon beams with energies of 20-25 keV with a repetition rate of 1 MHz or higher. At reasonable energies of the drive linac of 8-10 GeV optimum FEL performance requires an electron beam with emittance of 0.1 mm.mrad or lower. Higher value of the emittance leads to essential degradation in FEL performance and significant increase in required undulator length. In this work we try to estimate the ultimate beam brightness and bunch repetition rate that may be achieved with existing electron injector technologies and outline possible ways of obtaining beams with the parameters required for future FELs. In particular, we will discuss possible injector designs for the ongoing UK XFEL project.
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Slides TU3D5 [3.260 MB]
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