...
Nearly all user experiments using the multi-TW beam require excellent contrast to be successful. To achieve highest baseline pulse contrast, the short pulse laser system employs a double-CPA front end. After initial chirped pulse amplification of the oscillator pulses at 120 Hz, the beam is recompressed and passed through a nonlinear filter (with an OPA and SFG-based pulse cleaner [1] replacing XPW starting in Run 17) and then stretched again for final amplification. This filter removes prepulses and pedestal energy that builds up primarily in the laser front end. Measurements utilizing third order autocorrelation techniques revealed a contrast better than 107 in the > 3 picosecond range using a double CPA pulse cleaning system. To further increase this contrast, MEC can provide a 2nd harmonic stage that, in combination with dichroics, should theoretically achieve better than 1014 contrast beyond 3 ps, while sacrificing pulse energy (output ~300 mJ at 400 nm).
Timing Jitter and Synchronization with the LCLS X-ray Beam
...
- On-shot diagnostics:
- Time tool (synchronization)
- Pulse energy
- Near-field beam profile
- Wavefront
- Equivalent plane focal spot
- Spectrum
- On-demand diagnostics (off-line)
- SPIDER
- 3rd order autocorrelation
- Far-field beam profile
- Motorized power meters