1. PESP-2002 Sept.4-6 2002 High Power Diode Laser System for SHR D.Cheever, M.Farkhondeh, B.Franklin, E.Tsentalovich, T.Zwart MIT-Bates Linear Accelerator Center Middleton, MA 01949, USA r

2. PESP-2002 Sept.4-6 2002 Requirements CW TiSa laser: - any time structure can be tailored, - tunable, - moderate stability - peak power 3.5 W Pulsed TiSa laser: - peak power - hundreds Watts, - tunable - low stability - max rep. rate  10 Hz Fiber-based laser: - doesn’t work (power limitations) Diode array laser !!!

3. PESP-2002 Sept.4-6 2002 Diode array laser Power: CW mode up to 50-60 W, Pulsed mode up to 200 W Very high stability Very convenient in operation No maintenance needed Not tunable ( = 808 nm) “Emmitance” ~ 200 mm  mrad (For Gaussian-limited beam “emmitance” ~ ~ 1 mm  mrad )

4. PESP-2002 Sept.4-6 2002 Matching wavelength SLAC crystal (at =808 nm) : QE ~ 0.2 - 0.3 %, P ~ 80 % St. Petersburg crystal St. Petersburg crystal (Bates data)

5. PESP-2002 Sept.4-6 2002 MIT-Bates Polarized Source

6. PESP-2002 Sept.4-6 2002 Laser inside Faraday cage

7. PESP-2002 Sept.4-6 2002 Laser outside the cage

8. PESP-2002 Sept.4-6 2002 Polarization Reversal

9. PESP-2002 Sept.4-6 2002

10. PESP-2002 Sept.4-6 2002 Optics for “monster” Pockels cell HPC /2 Extinction ratio ~ 135 (~ 200 for Gaussian beam). P > 99 %

11. PESP-2002 Sept.4-6 2002 Driver for the diode laser 10  laser Feedback PITA 1 

12. PESP-2002 Sept.4-6 2002 Pulse from the fast driver Rise time ~ 0.2 usec Droop ~ 5 %

13. PESP-2002 Sept.4-6 2002 SUMMARY Set up for storage mode:- fast driver - slow polarization reversal with /2 plate Perfect match ! Set up for stretcher/(no ring) mode:- driver with feedback options - fast helicity reversal with Pockels cell Rep. rate 600 Hz Polarization reversal at 600 Hz The ability to control helicity-correlated asymmetries for parity-violating experiments needs to be demonstrated The ability to run high average current with High-P crystals over long experiments needs to be demonstrated