FEL2014 - List of Authors (Wang, L.)

Paper

Title

Page

Laser Seeding Schemes for Soft X-rays at LCLS-II

223

G. Penn
LBNL, Berkeley, California, USA
P. Emma, E. Hemsing, G. Marcus, T.O. Raubenheimer, L. Wang
SLAC, Menlo Park, California, USA

Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract Nos. DE-AC02-05CH11231 and DE-AC02-76SF00515.
The initial design for LCLS-II incorporates both SASE and self-seeded configurations. Increased stability and/or coherence than is possible with either configuration may be provided by seeding with external lasers followed by one or more stages of harmonic generation, especially in the soft x-ray regime. External seeding also allows for increased flexibility, for example the ability to quickly vary the pulse duration. Studies of schemes based on high-gain harmonic generation and echo-enabled harmonic generation are presented, including realistic electron distributions based on tracking through the injector and linac.

TUP032

FEL Simulation and Performance Studies for LCLS-II

456

G. Marcus, Y. Ding, P. Emma, Z. Huang, T.O. Raubenheimer, L. Wang, J. Wu
SLAC, Menlo Park, California, USA

The design and performance of the LCLS-II free-electron laser beamlines are presented using start-to-end numerical particle simulations. The particular beamline geometries were chosen to cover a large photon energy tuning range with x-ray pulse length and bandwidth flexibility. Results for self-amplified spontaneous emission and self-seeded operational modes are described in detail for both hard and soft x-ray beamlines in the baseline design.

THP025

Linear Accelerator Design for the LCLS-II FEL Facility

743

P. Emma, J.C. Frisch, Z. Huang, H. Loos, A. Marinelli, T.J. Maxwell, Y. Nosochkov, T.O. Raubenheimer, L. Wang, J.J. Welch, M. Woodley
SLAC, Menlo Park, California, USA
J. Qiang, M. Venturini
LBNL, Berkeley, California, USA
A. Saini, N. Solyak
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
The LCLS-II is an FEL facility proposed in response to the July 2013 BESAC advisory committee, which recommended the construction of a new FEL light source with a high-repetition rate and a broad photon energy range from 0.2 keV to at least 5 keV. A new CW 4-GeV electron linac is being designed to meet this need, using a superconducting (SC) L-band (1.3 GHz) linear accelerator capable of operating with a continuous bunch repetition rate up to 1 MHz at ~16 MV/m. This new 700-m linac is to be built at SLAC in the existing tunnel, making use of existing facilities and providing two separate FELs, preserving the operation of the existing FEL, which can be fed from either the existing copper or the new SC linac. We briefly describe the acceleration, bunch compression, beam transport, beam switching, and electron beam diagnostics. The high-power and low-level RF, and cryogenic systems are described elsewhere.

Poster THP025 [0.627 MB]

THP026

Design Study of LCLS Chirp-Control with a Corrugated Structure

748

Z. Zhang, K.L.F. Bane, Y. Ding, Z. Huang, R.H. Iverson, T.J. Maxwell, G.V. Stupakov, L. Wang
SLAC, Menlo Park, California, USA
P. Frigola, M.A. Harrison, M. Ruelas
RadiaBeam, Marina del Rey, California, USA

The purpose of this paper is to investigate the use of flat metallic plates with small corrugations as a passive dechirper, studying its effects on beam dynamics. Similar systems have been tested in Pohang and Brookhaven at relatively low energies (~100 MeV) and with relatively long bunches (>1ps) [*,**]. Four meters of such a structure are being machined by Radiabeam Systems for use in the LCLS with a high energy and femtosecond electron beam. In this paper we use a field matching program to obtain the longitudinal and transverse wakes for the purpose of the LCLS dechirper design. In addition, we fit the longitudinal wake to simple functions, so that one can obtain the wake without resorting to the field matching program. Since the transverse wakes–both dipole and quadrupole wakes–are strong, we include beam dynamics simulations to find the tolerances for injection jitter and misalignment in the LCLS.
* P. Emma, et al. PRL 112, 034801
** M. Harrison, et al., NaPAc 2013, Pasadena, USA

THP029

MOGA OPTIMIZATION DESIGN OF LCLS-II LINAC CONFIGURATIONS

763

L. Wang, P. Emma, Y. Nosochkov, T.O. Raubenheimer, M. Woodley, F. Zhou
SLAC, Menlo Park, California, USA
C. F. Papadopoulos, J. Qiang, M. Venturini
LBNL, Berkeley, California, USA

The Linac Coherent Light Source II (LCLS-II) will generate extremely intense X-ray flashes to be used by researchers from all over the world. The FEL is powered by 4 GeV superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. LCLS-II will provide large flexibility in bunch charge and peak current. Multi-Objective Genetic Algorithm (MOGA) is applied to optimize the machine parameters including bunch compressors system, linearizer, de-chirper, RF phase and laser heater, in order to minimize the energy spread, collective effects and emittance. The strong resistive wall wake field along the 2km bypass beam line acts as a natural de-chirper. This paper summarizes the optimization of various configurations.

Poster THP029 [0.702 MB]

Paper	Title	Page
MOP075	Laser Seeding Schemes for Soft X-rays at LCLS-II	223
	G. Penn LBNL, Berkeley, California, USA P. Emma, E. Hemsing, G. Marcus, T.O. Raubenheimer, L. Wang SLAC, Menlo Park, California, USA
	Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract Nos. DE-AC02-05CH11231 and DE-AC02-76SF00515. The initial design for LCLS-II incorporates both SASE and self-seeded configurations. Increased stability and/or coherence than is possible with either configuration may be provided by seeding with external lasers followed by one or more stages of harmonic generation, especially in the soft x-ray regime. External seeding also allows for increased flexibility, for example the ability to quickly vary the pulse duration. Studies of schemes based on high-gain harmonic generation and echo-enabled harmonic generation are presented, including realistic electron distributions based on tracking through the injector and linac.

TUP032	FEL Simulation and Performance Studies for LCLS-II	456
	G. Marcus, Y. Ding, P. Emma, Z. Huang, T.O. Raubenheimer, L. Wang, J. Wu SLAC, Menlo Park, California, USA
	The design and performance of the LCLS-II free-electron laser beamlines are presented using start-to-end numerical particle simulations. The particular beamline geometries were chosen to cover a large photon energy tuning range with x-ray pulse length and bandwidth flexibility. Results for self-amplified spontaneous emission and self-seeded operational modes are described in detail for both hard and soft x-ray beamlines in the baseline design.

THP025	Linear Accelerator Design for the LCLS-II FEL Facility	743
	P. Emma, J.C. Frisch, Z. Huang, H. Loos, A. Marinelli, T.J. Maxwell, Y. Nosochkov, T.O. Raubenheimer, L. Wang, J.J. Welch, M. Woodley SLAC, Menlo Park, California, USA J. Qiang, M. Venturini LBNL, Berkeley, California, USA A. Saini, N. Solyak Fermilab, Batavia, Illinois, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-76SF00515. The LCLS-II is an FEL facility proposed in response to the July 2013 BESAC advisory committee, which recommended the construction of a new FEL light source with a high-repetition rate and a broad photon energy range from 0.2 keV to at least 5 keV. A new CW 4-GeV electron linac is being designed to meet this need, using a superconducting (SC) L-band (1.3 GHz) linear accelerator capable of operating with a continuous bunch repetition rate up to 1 MHz at ~16 MV/m. This new 700-m linac is to be built at SLAC in the existing tunnel, making use of existing facilities and providing two separate FELs, preserving the operation of the existing FEL, which can be fed from either the existing copper or the new SC linac. We briefly describe the acceleration, bunch compression, beam transport, beam switching, and electron beam diagnostics. The high-power and low-level RF, and cryogenic systems are described elsewhere.
	Poster THP025 [0.627 MB]

THP026	Design Study of LCLS Chirp-Control with a Corrugated Structure	748
	Z. Zhang, K.L.F. Bane, Y. Ding, Z. Huang, R.H. Iverson, T.J. Maxwell, G.V. Stupakov, L. Wang SLAC, Menlo Park, California, USA P. Frigola, M.A. Harrison, M. Ruelas RadiaBeam, Marina del Rey, California, USA
	The purpose of this paper is to investigate the use of flat metallic plates with small corrugations as a passive dechirper, studying its effects on beam dynamics. Similar systems have been tested in Pohang and Brookhaven at relatively low energies (~100 MeV) and with relatively long bunches (>1ps) [,]. Four meters of such a structure are being machined by Radiabeam Systems for use in the LCLS with a high energy and femtosecond electron beam. In this paper we use a field matching program to obtain the longitudinal and transverse wakes for the purpose of the LCLS dechirper design. In addition, we fit the longitudinal wake to simple functions, so that one can obtain the wake without resorting to the field matching program. Since the transverse wakes–both dipole and quadrupole wakes–are strong, we include beam dynamics simulations to find the tolerances for injection jitter and misalignment in the LCLS. P. Emma, et al. PRL 112, 034801 ** M. Harrison, et al., NaPAc 2013, Pasadena, USA

THP029	MOGA OPTIMIZATION DESIGN OF LCLS-II LINAC CONFIGURATIONS	763
	L. Wang, P. Emma, Y. Nosochkov, T.O. Raubenheimer, M. Woodley, F. Zhou SLAC, Menlo Park, California, USA C. F. Papadopoulos, J. Qiang, M. Venturini LBNL, Berkeley, California, USA
	The Linac Coherent Light Source II (LCLS-II) will generate extremely intense X-ray flashes to be used by researchers from all over the world. The FEL is powered by 4 GeV superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. LCLS-II will provide large flexibility in bunch charge and peak current. Multi-Objective Genetic Algorithm (MOGA) is applied to optimize the machine parameters including bunch compressors system, linearizer, de-chirper, RF phase and laser heater, in order to minimize the energy spread, collective effects and emittance. The strong resistive wall wake field along the 2km bypass beam line acts as a natural de-chirper. This paper summarizes the optimization of various configurations.
	Poster THP029 [0.702 MB]