JACoW is a publisher in Geneva, Switzerland that publishes the proceedings of accelerator conferences held around the world by an international collaboration of editors.
TY - UNPB AU - Sudar, N.S. AU - Ding, Y. ED - Braun, Hans-Heinrich ED - Chrin, Jan ED - Ganter, Romain ED - Hiller, Nicole ED - Schaa, Volker RW TI - An Analytical Method for Longitudinal Phase Space Backtracking J2 - Proc. of FLS2023, Luzern, Switzerland, 27 August-01 September 2023 CY - Luzern, Switzerland T2 - ICFA Advanced Beam Dynamics Workshop T3 - 67 LA - english AB - Electron beam driven light sources require a longitudinal phase space exhibiting narrow energy spread and high peak current. In linear accelerators this is typically realized by employing multiple stages of bunch compression coupled with various techniques to shape the electron beam chirp. Increases in repetition rate limit many of these manipulations due to the high average beam power. This encourages manipulation of the electron beam properties at the source or low energy area of the accelerator. However, determining the upstream phase space properties that will lead to a particular final phase space proves difficult due to the many free variables of the accelerator and collective effects. Here we present an analytical method for tracking polynomial coefficients describing the final electron beam chirp and current profile backwards to an upstream point in the accelerator. This is written to arbitrary polynomial order and includes analytical expressions for collective effects. The method is applied to the LCLS-II linac, tracking from the undulator entrance back to the injector exit. The example case provided here leads to a 4 kA peak current flat top distribution and 0.1% RMS energy spread at the undulator entrance, representing a significant increase in the LCLS-II beam brightness. Forward tracking in Elegant of the found ideal distribution at the injector exit and accelerator configuration shows good comparison. PB - JACoW Publishing CP - Geneva, Switzerland ER -