F. Grüner-Laser-driven Brilliant X-ray Sources

Laser-driven Brilliant X-ray Sources

Lab-scale

ELI Workshop, Prague, Apr 26-27, 2010, F. Grner, LMU/MPQ

Basic setup as seen by


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


Laser Wakefield Acceleration how to accelerate electrons?typical length scale = plasma wavelength

plasma laser pulse

bubble

~ 5 fsPIC simulation (M. Geissler)

Ez ~ TV/m


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!]


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


.thank you for your attention


F. Grüner-Laser-driven Brilliant X-ray Sources

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