FEL2013 - List of Authors (Wang, L.)

Paper

Title

Page

Multi-Objective Genetic Optimization for LCLS-II X-Ray FEL

12

L. Wang, T.O. Raubenheimer
SLAC, Menlo Park, California, USA

The Linac Coherent Light Source II (LCLS-II) will build on the success of the world's most powerful X-ray laser, the Linac Coherent Light Source (LCLS). It will add two new X-ray laser beams and room for additional new instruments, greatly increasing the number of experiments carried out each year. Multiple operation modes are proposed to accommodate a variety of user requirements. There are a large number of variables and objectives in the design. For each operation mode, Multi-Objective Genetic Algorithm (MOGA) is applied to optimize the machine parameters in order to minimize the jitters, energy spread, collective effects and emittance. The optimal designs for various operation modes are presented in this paper. The phase and voltage of the linac RF, R56 at the two bunch compressors are optimized. The CSR (coherent synchrotron radiation) can induce large emittance growth, which is minimized by optimizing the phase advance between the compressor and the bend section. The final emittance at the beginning of the undulator is just about 1um and even lower.

Slides MOOCNO02 [3.046 MB]

WEPSO10

Increased Stability Requirements for Seeded Beams at LCLS

518

F.-J. Decker, W.S. Colocho, Z. Huang, R.H. Iverson, A. Krasnykh, A.A. Lutman, M.N. Nguyen, T.O. Raubenheimer, M.C. Ross, J.L. Turner, L. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
Running the Linac Coherent Light Source (LCLS) with self-seeded photon beams requires better electron beam stability, especially in energy, to reduce the otherwise huge intensity variations of more than 100%. Code was written to identify and quantify the different jitter sources. Some improvements are being addressed, especially the stability of the modulator high voltage of some critical RF stations. Special setups like running the beam off crest in the last part of the linac can also be used to reduce the energy jitter. Even a slight dependence on the transverse position was observed. The intensity jitter distribution of a seeded beam is still more contained with peaks up too twice the average intensity, compared to the jitter distribution of a SASE beam going through a monochromator, which can have damaging spikes up to 5 times the average intensity.

Paper	Title	Page
MOOCNO02	Multi-Objective Genetic Optimization for LCLS-II X-Ray FEL	12
	L. Wang, T.O. Raubenheimer SLAC, Menlo Park, California, USA
	The Linac Coherent Light Source II (LCLS-II) will build on the success of the world's most powerful X-ray laser, the Linac Coherent Light Source (LCLS). It will add two new X-ray laser beams and room for additional new instruments, greatly increasing the number of experiments carried out each year. Multiple operation modes are proposed to accommodate a variety of user requirements. There are a large number of variables and objectives in the design. For each operation mode, Multi-Objective Genetic Algorithm (MOGA) is applied to optimize the machine parameters in order to minimize the jitters, energy spread, collective effects and emittance. The optimal designs for various operation modes are presented in this paper. The phase and voltage of the linac RF, R56 at the two bunch compressors are optimized. The CSR (coherent synchrotron radiation) can induce large emittance growth, which is minimized by optimizing the phase advance between the compressor and the bend section. The final emittance at the beginning of the undulator is just about 1um and even lower.
	Slides MOOCNO02 [3.046 MB]

WEPSO10	Increased Stability Requirements for Seeded Beams at LCLS	518
	F.-J. Decker, W.S. Colocho, Z. Huang, R.H. Iverson, A. Krasnykh, A.A. Lutman, M.N. Nguyen, T.O. Raubenheimer, M.C. Ross, J.L. Turner, L. Wang SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515. Running the Linac Coherent Light Source (LCLS) with self-seeded photon beams requires better electron beam stability, especially in energy, to reduce the otherwise huge intensity variations of more than 100%. Code was written to identify and quantify the different jitter sources. Some improvements are being addressed, especially the stability of the modulator high voltage of some critical RF stations. Special setups like running the beam off crest in the last part of the linac can also be used to reduce the energy jitter. Even a slight dependence on the transverse position was observed. The intensity jitter distribution of a seeded beam is still more contained with peaks up too twice the average intensity, compared to the jitter distribution of a SASE beam going through a monochromator, which can have damaging spikes up to 5 times the average intensity.