Title: XFEL Photo Injector Simulations
1XFEL Photo Injector Simulations
2XFEL Photo Injector Layout
Superconducting TESLA module (ACC1)
RF gun
- Injector parameters to be optimized
- Cathode laser XYrms, (Trms)
- RF-Gun launch RF phase
- Solenoid position, peak field (current)
- Booster position, gradient, RF phase
3XFEL Photo Injector Simulations
4XFEL Photo Injector Simulations
Beam transverse rms size and normalized emittance
proj.emittance 0.87 mm mrad
5XFEL Photo Injector Simulations
Beam energy and rms energy spread
Longitudinal emittance and bunch rms length
6XFEL Photo Injector Simulations
Influence of thermal emittance from the photo
cathode
Normalized transverse emittance after XFEL
injector as function of the initial kinetic
energy of the photo emitted electrons
Slice emittance _at_z18m
7Dependence on Gun Gradient (PITZ case)
8Solenoid Position
z0.276m
z0.41m
New solenoid position requires modification of
the input coupler (increased length of coaxial
part).
What can be achieved with actual solenoid
position?
9Change the Optimization Procedure
Cathode laser (XYrms, Trms) gun parameters
(RF Phase, Imain, sol.pos)
Emittance
0 step. tune the bunch charge
Qbunch-gtQ1nC(_at_z5cm) Emission effects (SC,
Schottky)
Xrms,Xemit
1 step. Run ASTRA till z5m
10Re-Optimization (Actual Solenoid Position)
Also the current solenoid z-position is OK
11Cathode Laser Ellipsoid Vs. Cylinder
12XFEL Injector Simulations Outlook
- Studies of tolerances for cathode laser
parameters FWHM, rise/fall time, flat-top
modulation - Influence of the vacuum components (like a vacuum
mirror, diagnostic cross etc) on the beam quality - Impact of photo injector imperfections
(misalignment)