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Laser-driven Brilliant X-ray Sources
Lab-scale
ELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
Basic setup as seen by
ELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
Basic setup in reality
capillary pre-ionized gas 200 m diameter
undulator sub-cm period
high-intensity laser energy ~ J pulse length ~ 25 fs
magnetic lenses 500 T/m gradient
diagnostics/ applications
ELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
Laser Wakefield Acceleration how to accelerate electrons?typical length scale = plasma wavelength
plasma laser pulse
bubble
~ 5 fsPIC simulation (M. Geissler)
Ez ~ TV/m
ELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
Beam Transport and Undulator
L = 30 cm
field gradient: 500 T/m aperture 6 mm
u = 5mm K = 0.55gap = 1.2mm
self-made.ELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
First breakthru: laser-driven soft x-ray undulator source
M. Fuchs,, F. Krausz, S. Karsch, F. Grner,
Nature Phys. 5, 826 (2009)
200 MeV, 5 pCELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
Stability and Tuneability: achieved via mini-quadstuneability via lense positions
response function
electron energy bandpassELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
Laser Wakefield Acceleration towards applications
from 1979 to 2009
??ELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
Near future plans: ultra-short x-ray sourcetypical length scale = plasma wavelength
laser pulse
bubble
already today: 10,000 photons/(shot mrad2 0.1%b.w.) in 5 fs [BESSY femtoslicing: 1,000 photons in 100 fs ]First real application: x-ray pump-probe experiments 2-5 keV, 5 fs, focused, well synchronized
~ 5 fs
ultimate goal: sub-fs x-rays
[100 attosecond XFEL feasible!]
ELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
Towards higher electron energies with same driver laser~c
vp
electron faster than wake accelerating part
dephasing:
dephasing length:maximum energy:
plasma up-ramp
solution:
W. Rittershofer, C. Schroeder, E. Esarey, F. Grner, W.Leemans; accepted in Phys. ELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ of Plasma
Cryogenic Undulatorscoercivity
less beam damage shorter periods @ still large K value larger gap @ same K-valuefield strength
energy density
cooperation with HZB (J. Bahrdt) and UCLA (J. Rosenzweig): first prototype of a PrFeB-undulatorELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
What is a free-electron-laser (FEL) ?
electron accelerator
undulator
electron trajectory undulator radiationELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
Towards lab-scale FELs laser-driven: ultra-high peak current (up to 100 kA) significant reduction of saturation length todays experimental parameters dont allow FEL process
solution 1: improve beam quality (long way) solution 2: design minimal demonstration:signal-to-background ratio
GENESIS simulationincluding:
space-charge wakefields beam transportELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
From Table-Top to Lab-scale XFELs
Laser focusing
beam transport and FEL
layout from start-to-end simulations for a 5 keV-XFEL: 5 fs X-ray pulse length 2 GeV electrons, 1 nC charge
~ 1012 photons / shot peak brilliance ~ 1030 ph/(s mm mrad 0.1 % bw)ELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
summary laser-driven undulator source first application experiment
lab-scale XFELcryogenic short-period undulator
laser-plasma accelerator
mini-quads
ELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
.thank you for your attention
ELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ
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