Bill White Drive Laser April 16, Drive Laser Commissioning Experience Reminder of requirements on Drive Laser Thales laser Transport system Commissioning in three areas Thales laser and it’s specs Beam conditioning and transport Virtual cathode alignment Lessons learned – remaining issues Future

Bill White Drive Laser April 16, UV pulse goals rise and fall times < 1 ps flat-top, < 8% peak-to peak IR to UV conversion efficiency > 10 %, 2.5 mJ 255 nm nm, < 2% energy stability 120 Hz, MTBF > 5000 hours Spatial Profile FWHM = 1.2 – 3.0 mm Temporal Profile FWHM = 10 ps (5-20 ps)

Bill White Drive Laser April 16, Thales Laser system Oscillator Stretcher Dazzler Regen Preamplifier Final Amplifier Compressor UV Conversion

Bill White Drive Laser April 16, Transport Laser Bay Launch System Beam shaper Vacuum cell Zoom Transport tube Table in the tunnel Photocathode Virtual Cathode Steering system Active Steering Stabilization L1 L2 L3 L4 L5 L6 Waveplate Polarizer Powermeter Camera Shutter

Bill White Drive Laser April 16, Active Steering Stabilization In order to meet centroid position stability requirement (min 60μm) M6 should be stabilized with 35μrad accuracy Sensitivity of the mirror mount 7arcsec – 34 μrad Camera From Virtual Cathode To Photocathode Laser Bay Transport Tube Table in the tunnel Steering Stabilization system test is underway M6 M5 M4 M3 M2 C2 C1

Bill White Drive Laser April 16, Transport System in the Laser Bay Laser Output Shaper Input Adjustment Shaper Lens Beam Size Adjustment Remotely Controlled Mirror To Transport tube

Bill White Drive Laser April 16, Optical System next to the Photocathode From Transport tube Lens Remotely Controlled Mirror Remotely Controlled Mirrors Steering Stabilization Camera Lead Blocks Lead Block Virtual Cathode camera In vacuum mirrorPhotocathode Powermeter

Bill White Drive Laser April 16, Transport Commissioning Transport Shaper Diagnostics Characterization Calibration of diagnostics GTL Installation Virtual Cathode

Bill White Drive Laser April 16, Timeline - Laser Commissioning Laser table and LSS in Vault Feb 13 th – Began taking UV into vault Feb 23 – GTL installation began VC March 1 to March 12. Gun Installation began March 12. ARR April 4 Beam April 5

Bill White Drive Laser April 16, Commissioning Issues Better Schedule coordination Too many people all working in small space Minor problems have widespread impact Because of shortened laser commissioning, some laser commissioning will continue with injector commissioning

Bill White Drive Laser April 16, Commissioning Issues Cross correlatorStreak Camera

Bill White Drive Laser April 16, Temporal Pulse Shaping The achieved temporal pulse shape meets physics requirements for the injector commissioning Plan to improve the temporal shape Replace the Lyot filter in the regen amplifier by the edge mirrors – this will reduce oscillations Continue working on the Dazzler settings and the optimum UV conversion crystals lengths Thales engineers are coming back in September to continue working on shaping Plan B – to use stacking of Gaussian pulses Design and parts for pulse stacking are in place

Bill White Drive Laser April 16, Commissioning Issues Transport Tubes 10m long Hydro-carbons coating and damaging inside of windows when exposed to UV Dust inside tube settling on inside of windows – Damage and diffraction Will go to less expensive windows and on site pump so the windows can be replaced more quickly.

Bill White Drive Laser April 16, GBS-UV H Commissioning Issues Newport aspheric telescope Converts Gaussian to flat-top Requires good Gaussian input Very sensitive to alignment Aperture is just as good and much simpler to align Allows flexibility Simplifies overall transport

Bill White Drive Laser April 16, Commissioning Issues Oscillator Problems Picomotor translation stage instability Femtolase will replace Coarse control currently disabled/manual Phase ambiguity due to locking at 476MHz Impacts phasing of RF Can make double pulse Could be solved with newly available upgrade Replacing this oscillator will solve both problems and provide greater seed energy

Bill White Drive Laser April 16, Future - Hand Over to Ops Now Develop procedures for laser Automate things that can and need to be automated August 07 Down Train Operations Group on typical Operation Procedures Hand off laser by Jan 08 Laser Group will support Ops Scheduled Maintenance Issues that arise outside of the typical operation envelope

Bill White Drive Laser April 16, End