1. 17 th HAPL Meeting Washington, DC October 30, 2007 Naval Research Laboratory Plasma Physics Division Washington, DC Work supported by DOE/NNSA/DP Optical System and staging of the Electra KrF laser facility NRL M. Wolford M. Myers J. Sethian J. Giuliani Commonwealth Tech F. Hegeler RSI P. Burns SAIC R. Jaynes

2. LPX 305 i Input 0.5 J 10 cm x 10 cm Cylindrical lens Pair Telescope 1 cm x 3 cm 3 cm x 3 cm OutputInput BG 28 LA Vision Improved Near Field Measurements since last HAPL Meeting

3. 80% Ar, 0.3% F 2 Single Beam Electra Pre-Amplifier Yield

4. Voltage OutputInput 64.8 ns Single Beam Timing Between Laser Input, Laser Output and Electron Beam (10 J)

5. 1 23 4 5 6 Input Output Single Beam Output Time Dependent Intensity

6. Cause of Discrepancy Single Beam Pre-Amplifier Yield Function of Input Timing

7. LPX PLCC Cylindrical Optics 6 m Nike Lens Beamsplitter Calorimeter Photodiode Combo Beam 1 ~ 373 mJ Beam 2 ~ 397 mJ PD 2 PD1 Two Beam Angularly Multiplex Preamplifier

8. Calorimeter Data 25 J Laser Output Beam 1Beam 2 8.1 cm 7.6 cm 9.0 cm 9.7 cm 25 J Output of Two Beam Angularly Multiplex Preamplifier Dimensions

9. LPX Pre-AMPMain AMP Electra Laser System Calorimeter Photodiode (PDM) Photodiode (PDTarget) 42 m

10. PDM 12 34 56 Pdtarget Big Calorimeter 33 x 33 cm 2 Calorimeter Nike Calorimeters 18 x 18 cm 2 Calorimeters Sum Full Laser System 452 J Single Shot Yield

11. Full Laser System Laser Yield Depends on Timing Between LPX, Pre Amplifier and Main Amplifier The Difference if one or both beams are amplified in Pre-amplifier Timing Discrepancy Between Amplifiers

12. PDM 12 34 56 PDTarget Full Laser System Yield 1.585 kJ in One Second 5 Hz Burst Single Pass Double Pass

13. Single Pass Double Pass Why laser Yield is Decreasing with Shot #? Observation: Larger Percentage Laser Intensity Decrease was observed after one pass than double pass Probable Cause: A declining input laser intensity into the main amplifier

14. Single Shot 5 shot Rep-Rate Burst Cross Hairs for Scale Near Field (7m) Beam Profile Suggests increase in Phase Aberration is the cause for the drop in laser energy for the Electra Laser System

15. 500 shots @ 5 Hz 5 shots @ 5 Hz Pre-amp without gas recirculator Main-amp with gas recirculator Pre-amplifier Needs Recirculator For Rep-Rate Operation

16. Electra Laser System 2.5 kJ 2 second burst @ 5 Hz All Components 5 Hz operational for longer bursts Again, Low Yield for later shots due to Pre-Amp Phase Aberrations, will be corrected with Recirculator Calorimeter Response

17. 1)Pre-Amp Recirculator (Design Complete) (For Beam Quality, Consistent Rep-Rate Output) 2)Improved Coupling from Pre-Amp to Main Amp 3)Improved timing control, Reduced Jitter (improvement already made) 4)Increase and Improve Diagnostics for KrF Code Comparison 5)Strip Cathode for Pre-Amp (Increased Energy Deposition in laser gas by ~25%) On Going Improvements in Laser System Since Measurements were made