FEL2013 - List of Authors (Gruener, F.J.)

Paper	Title	Page
MOPSO08	Unaveraged Modelling of a LWFA Driven FEL	43
	L.T. Campbell, B.W.J. MᶜNeil USTRAT/SUPA, Glasgow, United Kingdom F.J. Grüner, A.R. Maier CFEL, Hamburg, Germany F.J. Grüner, A.R. Maier Uni HH, Hamburg, Germany F.J. Grüner LMU, Garching, Germany
	Preliminary simulations of a Laser Wakefield Field Accelerator driven FEL are presented using the 3D unaveraged, broad bandwidth FEL simulation code Puffin. The radius of the matched low emittance electron beam suggests that the FEL interaction will be strongly affected by radiation diffraction. The parameter scaling and comparison between 3D and equivalent 1D simulations appears to confirm the interaction is diffraction dominated. Nevertheless, output powers are predicted to be greater than those of similar unaveraged FEL models. Possible reasons for the discrepancies between the averaged and unaveraged simulation results are discussed. [1] - AR Maier, A Meseck, S Reiche, CB Schroeder, T Seggebrock, and F Gruner, Phys Rev X 2, 031019 (2012)

MOPSO69	Free-Electron Lasers Driven by Laser-Plasma Accelerators Using Decompression or Dispersion	117
	C.B. Schroeder, E. Esarey, W. Leemans, J. van Tilborg LBNL, Berkeley, California, USA Y. Ding, Z. Huang SLAC, Menlo Park, California, USA F.J. Grüner, A.R. Maier CFEL, Hamburg, Germany
	Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Laser-plasma accelerators (LPAs) compactly produce fs beams with kA peak current and low (sub-micron) transverse emittance. Presently, the energy spread (percent-level) hinders the FEL application. Slippage of the fs beam in the FEL also suppresses lasing in the soft-x-ray, and longer, wavelength regimes. Given experimentally demonstrated LPA electron beam parameters, we discuss methods of beam phase space manipulation after the LPA to achieve FEL lasing. Decompression is examined as a solution to reduce the slice energy spread and slippage effects. We present a theoretical analysis of the stretched (and chirped) LPA beam in the FEL and determine the optimal decompression. Dispersion, coupled to a transverse gradient undulator (TGU), is also considered to enable LPA-driven FELs. Using a TGU has the advantages of shorter pulse duration, smaller bandwidth, and wavelength stabilization. We present numerical modeling for SASE and seeded XUV and soft x-ray FELs driven by LPAs after beam manipulation (decompression and/or dispersion). Recent advances in LPA performance will be presented, and experimental plans to demonstrate LPA-driven FEL lasing at LBNL will be discussed.

Paper

Title

Page

Unaveraged Modelling of a LWFA Driven FEL

43

L.T. Campbell, B.W.J. MᶜNeil
USTRAT/SUPA, Glasgow, United Kingdom
F.J. Grüner, A.R. Maier
CFEL, Hamburg, Germany
F.J. Grüner, A.R. Maier
Uni HH, Hamburg, Germany
F.J. Grüner
LMU, Garching, Germany

Preliminary simulations of a Laser Wakefield Field Accelerator driven FEL are presented using the 3D unaveraged, broad bandwidth FEL simulation code Puffin. The radius of the matched low emittance electron beam suggests that the FEL interaction will be strongly affected by radiation diffraction. The parameter scaling and comparison between 3D and equivalent 1D simulations appears to confirm the interaction is diffraction dominated. Nevertheless, output powers are predicted to be greater than those of similar unaveraged FEL models. Possible reasons for the discrepancies between the averaged and unaveraged simulation results are discussed.
[1] - AR Maier, A Meseck, S Reiche, CB Schroeder, T Seggebrock, and F Gruner, Phys Rev X 2, 031019 (2012)

MOPSO69

Free-Electron Lasers Driven by Laser-Plasma Accelerators Using Decompression or Dispersion

117

C.B. Schroeder, E. Esarey, W. Leemans, J. van Tilborg
LBNL, Berkeley, California, USA
Y. Ding, Z. Huang
SLAC, Menlo Park, California, USA
F.J. Grüner, A.R. Maier
CFEL, Hamburg, Germany

Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Laser-plasma accelerators (LPAs) compactly produce fs beams with kA peak current and low (sub-micron) transverse emittance. Presently, the energy spread (percent-level) hinders the FEL application. Slippage of the fs beam in the FEL also suppresses lasing in the soft-x-ray, and longer, wavelength regimes. Given experimentally demonstrated LPA electron beam parameters, we discuss methods of beam phase space manipulation after the LPA to achieve FEL lasing. Decompression is examined as a solution to reduce the slice energy spread and slippage effects. We present a theoretical analysis of the stretched (and chirped) LPA beam in the FEL and determine the optimal decompression. Dispersion, coupled to a transverse gradient undulator (TGU), is also considered to enable LPA-driven FELs. Using a TGU has the advantages of shorter pulse duration, smaller bandwidth, and wavelength stabilization. We present numerical modeling for SASE and seeded XUV and soft x-ray FELs driven by LPAs after beam manipulation (decompression and/or dispersion). Recent advances in LPA performance will be presented, and experimental plans to demonstrate LPA-driven FEL lasing at LBNL will be discussed.