1. Drive Laser Facility Layout Drive Laser Architecture Technical Issues
Injector Drive Laser Overview Sasha Gilevich, SLAC Lehman Review August 11, 2004
UV Specifications
Drive Laser Facility Layout
Drive Laser Architecture
Technical Issues
Summary
08/11/2004
Sasha Gilevich
Drive Laser Overview

2. UV Beam Specifications at Photocathode
Parameter
Nominal spec
Tolerance
wavelength
255nm nom.
Longer wavelength requires higher energy
+/- 3nm
pulse energy
> 0.20 mJ
(for 1 nC production with 3x10-5 QE)
< 2 % rms variation
fluence profile
Uniform (nom.) (adjustable)
< 10 % (peak-to-peak)
spot radius
1.2 mm
< 4 % (shot-to-shot)
Centroid pos.
< 10 % radius (RMS over multiple shots)
rep rate
120 Hz (10 to 120Hz)
power profile
Uniform
(adjustable plateau slope – 10% to +20%)
< 5% (RMS noise on the plateau)
profile FWHM
10 psec adjustable from 5 to 20 psec
< 2 % (RMS over multiple shots)
Rise/fall times
1.0 psec (10% - 90%)
timing jitter (with respect to RF)
< 0.5 psec (shot-to-shot)
08/11/2004
Sasha Gilevich
Drive Laser Overview

3. UV Launch and Condition.
Sector 20 Laser
Laser Bay
Drive Laser
Transport Tube
10 m
Laser Heater
Accelerators
RF Gun
UV Launch and Condition.
08/11/2004
Sasha Gilevich
Drive Laser Overview

4. Layout of Laser Room at S20
Space & Utilities for 2 Drive Lasers
08/11/2004
Sasha Gilevich
Drive Laser Overview

5. Drive Laser Room Specifications
Laser Room Requirements:
Class 100,000 clean room
Positive air pressure
Relative humidity 50% (+/-2%)
Temperature 20 to 22 deg C set point range (+/-0.5 deg C regulation)
Hepa filters
Two dimmer light switches with remote control
Floor: Clean room tile or epoxy paint
Walls: Epoxy paint
Grounded cable trays and optical tables
Ceiling Height: 10 feet
Ceiling Material: Clean room grade tiles sealed with gaskets.
08/11/2004
Sasha Gilevich
Drive Laser Overview

6. Drive Laser Structure
Drive Laser will be a fully purchased and integrated system
Optical transport, launch system, and diagnostics to be built by SLAC
Several laser companies showed interest and capability to build the system
Dazzler
08/11/2004
Sasha Gilevich
Drive Laser Overview

7. Steering Stabilization
UV Launch System
Steering Stabilization
Flattener
Spatial Shaper
Launch Grating
Cathode Window
Cathode Window
Telescope lenses
Telescope lenses
Grating and Trimmer
08/11/2004
Sasha Gilevich
Drive Laser Overview

8. Major Drive Laser Issues
Stability of the final amplifier pump lasers
Typical pulse-to-pulse energy stability of diode-pumped lasers <1%, lamp-pumped <3%
Reliability
The system should operate 24x7
Pumping system
Life time of the flash lamp – about h => Changing Lamps every ~2wks
Laser Diode Lifetime ~ 10000hr (~1year)
UV conversion unit
Shaping hardware
Short rise/fall time
Requires temporal pulse shaping
Amplification and UV conversion can affect the pulse shape
Broad bandwidth required for the temporal shaping reduces the efficiency of UV conversion
08/11/2004
Sasha Gilevich
Drive Laser Overview

9. R&D Effort UV Conversion and Spatial Shaping (ANL/SLAC)
Modeling of the UV conversion using SNLO software
Harmonic generation data using TiS CPA laser at ANL
Study effects of spatially flattened IR pulse after SHG and THG (Spatial Shaping of UV pulses has been done at SLAC)
Verify relay imaging of flattened UV pulse over extended distances
Study anamorphic and time slew conditioning of UV launch optics (especially grating efficiency)
Investigate UV grating damage threshold
Sasha Gilevich
08/11/2004
Drive Laser Overview

10. Spatial Profile Flattening of Ultraviolet Laser Pulses with Aspheric Refractive Optics B.F. Murphy, P.R. Bolton, A. Brachmann, J.F. Schmerge
The results of using the IBM refractive aspheric beam shaper at the output of the GTF laser (2psec, 263nm, 500μJ) 20 40 60 80
100
120
140
0.005
0.01
0.015
0.02 50
100
150
200 2 4 6
x 10 -3
Input
Output

11. Temporal Pulse Shaping (BNL/INFN/SLAC)
R&D Effort
Temporal Pulse Shaping (BNL/INFN/SLAC)
Install INFN purchased Dazzler
Study effects of amplification on pulse shape
Study effects of third harmonic conversion on pulse shape
Use shaped laser beam in electron beam experiments
Sasha Gilevich
08/11/2004
Drive Laser Overview

12. Temporal Pulse Shaping with the Dazzler
Preliminary Results Using an Acousto-optic Dispersive Filter For Laser Pulse Shaping
A Ghigo, F. Tazzioli, C.Vicario, S. De Silvestri, M. Nisoli, S. Stagira, I Boscolo, S. Cialdi, L. Serafini
INFN
Tests with Dazzler (INFN) integrated in Ti:S drive laser
will begin at BNL/DUVFEL in September 04
08/11/2004
Sasha Gilevich
Sasha Gilevich
Drive Laser Overview

13. Summary UV Specifications Defined R&D effort is defined and started
Details of the Drive Laser RFP defined
Several vendors showed capability to build the system
Major Issues
Stability
Reliability
Beam Shaping
08/11/2004
Sasha Gilevich
Drive Laser Overview