1. Solid State Lasers and Applications Proposed for Brookhaven’s ATF-II
Marcus Babzien –BNL
Igor Pogorelsky – BNL
Mikhail Polyanskiy -BNL

2. Outline ATF/ATF-II Introduction Facility Laser Systems Laser Details
History, capabilities, future goals
Facility Laser Systems
Overview, motivation
Laser Details
Photocathode Drive Laser
Pulse Train Laser
Strong Field Laser
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

3. ATF-II Introduction 8/1/16
ATF-II Solid State Lasers and Applications - M. Babzien

4. ATF: A National User Facility
Designated a DOE National User Facility in
Capabilities in:
Novel particle acceleration techniques R&D for smaller, more cost effective accelerators including:
Plasma and dielectric wakefield acceleration
Direct laser acceleration
Inverse free-electron lasers and more…
High-brightness radiation sources New techniques to produce electromagnetic radiation from THz to X-rays:
FEL R&D
Inverse Compton scattering
THz radiation from dielectric structures and more…
Beam manipulation and beam instrumentation Sophisticated longitudinal and transverse beam manipulation capabilities
Wide range of beam parameters enabling development and testing of advanced accelerator hardware, beam diagnostics and detectors
Ion generation and acceleration
Experimental hardware for producing supersonic hydrogen gas jets provides capabilities for generating mono-energetic multi-MeV proton beams
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

5. ATF: A National User Facility
Some facility facts:
In operation for users since 1992
Scientific R&D
Technology Demonstrations
Accelerator Capability Development
39 graduate degrees from the program with 8 more pending
Features:
A high-brightness 80-MeV Linac
A 2 TW picosecond CO2 laser system
And now an Ultrafast Electron Diffraction facility
Provides:
A highly trained staff to support a broad array of user experiments
A wide variety of experimental tools including those for laser-electron beam interactions
The ability to do beam-based, laser-based and combined-capability research
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

6. ATF-II: Our Vision LINAC Gun ATF-II in BNL Bldg. 912
To provide a facility for advanced accelerator R&D that:
Builds on the cutting edge science produced at the ATF for the last 25 years
Provides world-leading scientific and accelerator technology output for the next 25 years
RF & Electronics
Equipment Room
Experimental Hall #2
Experimental
Hall #1
Pulse Train Laser
CO2 & Strong Field Lasers + Experimental Area
LINAC
Gun
Ultrafast Electron Diffraction and Drive Laser Room
Electron Gun & Linac
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

7. Facility Laser Overview
8/1/16
ATF-II Solid State Lasers and Applications - M. Babzien

8. Facility Lasers Overview
Construct vacuum transport lines for flexible beam delivery of multiple lasers throughout facility L4 GH L1 LE L2 H1 L3
Pulse Train Laser
CO2 & Strong Field Lasers
Drive Laser
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

9. Facility Lasers Overview
The novel ATF short-pulse CO2 laser upgraded to higher power will continue to enable a unique experimental program
ATF-II will provide gas and solid state lasers both for facility operation and experimental use, as does ATF
However, it will utilize 4 independent laser systems for single bunch and pulse train operation of the photoinjector, and for experimental purposes
Provides for an overall increase in capabilities
Shrinks the parameter space of each system and allows better optimization
Provides some level of redundancy
Reduces operations impact of maintenance and future laser upgrades
System
Wave-lengths
Temporal Format
Repetition Rate
Energy,
Ppeak
Example Applications
CO2 mm
1x 2 ps
0.2 Hz
50 J, 25 TW
Ion Generation, LWFA, Compton Scattering
Photocathode driver
785
(262) nm
1x 100 fs
240 Hz
20 mJ,
200 MW
ATF-II RF gun
UED RF gun
Pulsetrain
1064,
(532),
(266) nm
1-100x 14 ps
< 10 Hz
Multiple pulse Compton scattering cavity
Strong Field
1x 50 fs
150 mJ, 3TW
Two-color Compton,
Two-color Ionization Injection LWA,
Plasma interferometry & holography,
Laser plasma shaping
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

10. Facility Lasers Overview
Effective laser strength for interactions may scale as l or l2 for many advanced accelerator mechanisms
CO2 laser at 10 um attractive (see M. Polyanskiy, this WG, Thursday afternoon)
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

11. Facility Lasers Overview
By offering a variety of laser capabilities, the experimental configurations increases and enable new opportunities
Wavelength coverage spanning 0.26 to 10 mm: e.g. Enables probing of wide range of LWPA plasma densities
Femtosecond to picosecond pulse durations have useful temporal durations and spectral bandwidths
Independently phased to each other and e-beam
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

12. Photocathode Drive Laser
8/1/16
ATF-II Solid State Lasers and Applications - M. Babzien

13. Photocathode Drive Laser
Drive Laser Room
8/1/16
ATF-II Solid State Lasers and Applications - M. Babzien

14. Photocathode Drive Laser
Ti:Al2O3 regen -> single output pulse
High repetition rate permits interleaved operation of multiple guns
UV for linac & UED guns, IR for UED target
Pulse shaping improvements for photocathode operation enabled by extra bandwidth and higher energy
Electronic synchronization will give advantages in experiment setup
IR Pulse Duration
100 fs
Repetition Rate
240 Hz
Pulse Energy
20 mJ (UV)
Stability
<1% RMS
Beam profile
M2<1.4
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

15. Photocathode Drive Laser
Pulse stacking limits attainable profiles to near-uniform, but is easy to align, optimize, and maintain
Birefringent wedges allow larger dynamic range of pulse delays at each stage
Tsinghua University a-BBO stacking
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

16. Pulse Train Laser
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

17. Pulse Train Laser Pulse Train Laser 8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

18. Pulse Train Laser High Reliability High performance
Typical utilization & availability is >80% of BNL workdays
Turn on time <15 minutes to full stability
Laser physicist not required for turn on/off & experimental runs
High performance
Energy on cathode ~0.5% RMS stability
Pointing stability 0.3% of beam diameter
Timing jitter 0.2ps
Trains up to 100 micropulses
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

19. Linac Pulse Train Operation
Pulse Train Laser
Linac Pulse Train Operation
Pockels Cell Modulator
Combine into one
Novel laser architecture mitigates gain depletion throughout pulse train & operates in conjunction with RF feedforward
Demonstrated & used extensively in FEL oscillator experiment ca. 1997, and again in for Radiabeam ICS experiment
Produce up to 100 pulses flat within 5%
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

20. Pulse Train Laser Useful for cavity–enhancement experiments
Increases average power in e-beam signal-limited experiments
Dual e-beam generation (independently phased drive & witness)
Alignment of optical cavities (ring-up/down), radiation emulation for experimental diagnostics
Energy: (dual pulse mode)
Transverse Distribution:
UV on cathode
0-30 mJ x 1 pulse
Range of beam size on cathode (Ø) mm
IR to CO2 laser
10 mJ x 2 pulses
Top-Hat Beam Profile Modulation (P-P)
<50%
Laser output: total IR
30 mJ
IR to gun
7.5 mJ
Repetition rate
1.5, 3 Hz
Green
2.5 mJ UV
500 mJ
Shot-to-shot stability (rms):
Timing
<0.2 ps
Energy: (pulse train mode) IR
~100 mJ / 20 pulses
Energy
<0.8 %
Pointing (fraction of beam Ø)
<0.3 %
Pulse duration (FWHM):
Oscillator IR
7 ps
Drift (8 hour P-P)
Amplified IR
14 ps
<15 ps
10 ps
<5%
8 ps
<1%
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

21. Strong Field Laser
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

22. Strong Field Laser Strong Field Laser 8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

23. MOPA with three multi-pass amplifiers for TW peak power levels
Strong Field Laser
MOPA with three multi-pass amplifiers for TW peak power levels
DAZZLER for dispersion management
Maintain beam profile for optimal focusing at interaction point
System has been operated and is in storage awaiting laser room completion
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

24. Strong Field Laser SFL Design Parameters Pulse parameter Value
Energy [J]
<0.15
Pulse duration FWHM [fs]
<50
Peak power [TW]
<3
Central wavelength [nm]
815 M2
<1.5
Focused with f/10 optics:
peak intensity [W/cm2]
~5x1017
dimensionless strength parameter a0
~0.5
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

25. Strong Field Laser Applications:
Two-color Compton scattering (TW or greater peak power) Y. Sakai et. al, Phys. Rev. ST Accel. Beams Vo. 14, (2011)
Utilize two widely-separated wavelengths to generate complex electron trajectory and modify X-ray spectrum
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

26. Strong Field Laser Applications:
Ion generation plasma shaping (energetic NIR pulse)
Two-color Compton scattering (TW or greater peak power) Y. Sakai et. al, Phys. Rev. ST Accel. Beams Vo. 14, (2011)
FEL seeding (transform-limited pulse)
Plasma wakefield holography (femtosecond, nm-bandwidth pulse)
Plasma interometry,shadowgraphy
Two-color ionization injection LWA (Trojan Horse)
8/1/16
AAC2016: ATF-II Solid State Lasers and Applications - M. Babzien

27. Most already implemented, integration needed
Conclusion
Wide variety of solid state laser beams will be available for ATF-II experimental program
Most already implemented, integration needed
New experiments & beam applications sought!
8/1/16
ATF-II Solid State Lasers and Applications - M. Babzien