Experimental Measurements of the ORION Photoinjector Drive Laser Oscillator Subsystem

Transcription

1 Experimental Measurements of the ORION Photoinjector Drive Laser Oscillator Subsystem D.T Palmer and R. Akre Laser Issues for Electron RF Photoinjectors October 23-25, 2002 Stanford Linear Accelerator Center

2 OUTLINE 1. Introduction 2. Laser System 1. Oscillator Subsystem 2. Amplifier Subsystem 3. Phase Noise 4. Discussion

3 Introduction SLAC CENTRAL RESEARCH YARD

4 ORION NLCTA

5 General Design Parameters of the ORION Facility Beam Energies Charge per Bunch Number of Bunches Transverse Emittance Bunch Length Charge Stability Bunch Timing Jitter Repetition Rate Average Beam Power Electron Source Drive Laser Source RF System Injector Linac High-Energy Linac 7 MeV (Source); 7-67 MeV (LE Hall); MeV (HE Hall) 0.25 nc optimum, adjustable up to a nominal maximum of 1 nc 1 or 2 (split charge) < 2x10-6 m, normalized rms (0.25 nc) 1.8 psec, rms (0.25 nc) 2.5% pulse-to-pulse 0.25 psec, rms 10 Hz 0.67 W at 67 MeV; 3.5 W at 350 MeV (1 nc bunches) 1.6 cell, S-band (2.856 GHz) Photoinjector, Mg cathode Commercial Ti:Sapphire, 266 nm wavelength, 1 mj output SLAC 5045 Klystron; Solid-State, NLC-type Modulator Two X-band (11.4 GHz), 0.9 m, 30 MV, NLC structures Four X-band, 1.8 m, 72 MV, NLC structures

6 Photoinjector Layout S-Band 150 cm Diagnostics X-Band cm

7 250 pc 2 Gun RF gradient Peak gun solenoid magnetic field Launch phase (centroid) Bunch charge 140 MV/m 3.09 kg 33 degrees 0.25 nc σ r [mm], ε x,n [mm-mrad] rms beam radius normalized emittance z [m] Injected bunch length (hard edge, T) Injected beam radius (hard edge) Initial accelerating gradient in X-band linacs Solenoid field in X- band linacs 6.3 ps 0.63 mm 33.6 MV/m 0.7 kg σ z (mm), δp/p (%) rms bunch length rms energy spread z [m] J.B. Rosenzweig et. al. ORION Baseline case

8 NLC Structure Support Studies Q T = 1 nc E = 67 MeV r o = 1 mm B z = 3 KG B a z = 750 G E z = 120 MV/m E a z = 33 MV/m D.T. Palmer et al. NLC Structure Support

9 S. Davies Accelerator Research Department B

10 ORION RF GUN S. Davies

11 ORION RF GUN Undergoing RF Cold UCLA Neptune Spare RF Gun

12 Waveguide Production Status -50 db Coupler In production 45 H-Bend Completed X-Band spool piece Completed X-Band Window... E-Bends... H-Bends... Straight Sections... S-Band Window Completed 5045 to Scarpuus Completed W\G pumping Station Completed RF Loads On Hand -3 db High Power Coupler On Hand

13 Laser System Overview

14 Drive Laser Minimum System Requirements and Performance Enhancements Parameter Pulse Repetition Frequency Laser Energy 1 Minimum System Requirement 10 Hz > 1 mj Performance Enhancements Laser Energy Jitter < 5% rms Best Effort UV Timing Jitter 2 < 500 fs, rms Best Effort Pulse Length (FWHM) 300 fs 10 ps Temporal Amplitude Profile Gaussian Uniform 3 Radial Amplitude Profile Approx. Uniform Best Effort 4 MTBF 5000 hours Footnotes: 1) Measured on a Gaussian temporal and radial profile beam. 2) Measured with respect to a 79 1/3 MHz external master RF clock 3) 5% ripple, peak to peak, 1 ps rise/fall times on 10% - 90% of full amplitude. 4) 10% ripple, peak to peak

15 Oscillator Subsystem

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18 ORION LASER OSCILLATOR FIRST 800 nm D.T. Palmer SLAC/ARDB 15 Oct 01

19 Photodiode Signal MHz nsec

20 Spectral Measurement λ = 16.1 nm

21 Autocorrelation Measurement

22 Autocorrelation Calibration T t = psec msec

23 Amplifier Subsystem Evolution X Spitfire Tripler Diode Pumped Nd:YLF 10 nm 1KHz Regenerative Amp + Multi-pass Stage + future upgrades

24 Phase Noise Circuit Diagram

25 0.142 o = 1 mv /3 MHz MHz

26 R. Akre and B. Cowan Accelerator Research Department B

27 R. Akre and B. Cowan Τ ~ 500 fsec Bandwidth: 1 Hz 1 MHz

28 Possible Noise Sources AM/PM conversion of Pump Noise PZT Response

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32 Discussion GO GIANTS!!!

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