Extended Data Fig. 6: Electron beam transport method comparison and consequence on FEL performance.
From: Seeded free-electron laser driven by a compact laser plasma accelerator
a–h Electron beam properties at undulator entrance: transverse phase–spaces (a,b,e,f) ; energy (c), current (d) and slice energy spread (g) longitudinal distributions ; charge density versus energy (h). Electron beam transported using BETA code with a Gaussian beam distribution at source point in (orange), using ELEGANT with same Gaussian beam at source point in (green) and using ELEGANT with electron beam energy and divergence distributions measured on the electron beam spectrometer (purple). Parameters for Gaussian beam definition at source point: Ee = 189 MeV, σe = 7%–RMS, divergence: \({\sigma }_{x^{\prime} }=0.85\) mrad–RMS and \({\sigma }_{y^{\prime} }=0.57\) mrad–RMS, normalized emittance: εx = 1.5 mm.mrad and εy = 1.0 mm.mrad, βx = 0.00562 m, βy = 0.00843 m, σz = 1μm–RMS.
