Laser plasma cathode by 12 TW, 50 fs laser and its ... plasma cathode by 12 TW, 50 fs laser and its...
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Laser plasma cathode by 12 TW, 50 fs laser and its application to radiation chemistry Mitsuru Uesaka Nuclear Engineering Research Laboratory , University of Tokyo June 26, 2004 International Symposium on Ultrafast Accelerators for Pulse Radiolysis
Transcript of Laser plasma cathode by 12 TW, 50 fs laser and its ... plasma cathode by 12 TW, 50 fs laser and its...
Laser plasma cathode by 12 TW, 50 fs laser and its application to radiation chemistry
Mitsuru Uesaka
Nuclear Engineering Research Laboratory ,
University of Tokyo
June 26, 2004International Symposium on
Ultrafast Accelerators for Pulse Radiolysis
Two New Accelerator RoomsCompact Medical Linac/Laser Plasma Beam Source
Linac Building(1st Floor)Fusion Blanket Building
(1st Floor)
Compact Medical Linac
Laser Plasma Beam Source
12TW 50fs Laser Plasma Beam Source
Amplifier 2
Amplifier 1
Clean Room
Regenerative amplifier
Pre-amplifier
YAG lasers
Laser system
Compressor chamberExperimental area
0.0 25.0 50.0 100.075.0[mm]
0.0
50.0
100.0
150.0
200.0
250.0
300.0
350.0
90
180
270
Energetic electronsup to ~40MeV
Spotsize D~8.1mm (FWHM)
Typical Image of Electron Beam Generation(Experimental Results: Signals on I.P.)
(180mm from gasjet)He 2.8x1019cm-3, Laser ~4.8TW
Experimental Set-up
Reference:T.Hosokai,et al.,Phys Rev.E 67,036407 (2003)
0 20 40 60Electron Energy [MeV]
PIC simulation
10-2
10-3
10-4
10-5
Elec
tron
Dist
ribut
ion
[arb
.un]
ElectronSignal[arb.un]
e-spectrum
a b c
Laserpulse
-1~1ns (Main Pulse)b: 1ns~3ns c: 2ns~5ns
Pump-and-probe Experiment Using Plasma Cathode at University of Tokyo
Fs laserProbe laser50fs(FWHM)
Pump EB40fs(FWHM)
SupersonicHe gas jet
Sample
Photo-detectorsfor measuringlight absorption
Fig. Schematic diagram of pump-probeexperiment using plasma cathode
Dominant factors for time resolution• EB for pump : 40fs(FWHM• Laser for probe : 50fs(FWHM• Timing jitter : ~0fs• Desynchronization in sample : ~1ps/mm
Current problems to be solved• Electron beam
- Energy spread : 100% → <10%- Charge : <1nC → >2nC- Stability of charge : 100% → <1%
Development of the system
Subject : radiolysis of liquids• Direct observation of radiation-inducedphysico-chemical processes within 1ps
(Vibrational&rotational relaxation, intramoleculreactions, geminate ion recombination etc.)
OPADelay stage
Delay stage
FC
Big Advantage of Laser Plasma Accelerator for Pump-and-probe analysis
・Synchronization is perfectly passive without any electronics.
12TW LaserBeam Splitter Optical Delay
Laser Plasma Cathode
Laser(50fs)
Electron Bunch(〜〜〜〜40fs)
・No timing jitter and drift between laser and secondary beam.
・Femtosecond time-resolved analysis is surely available after the bean quality and stability are upgraded.
Summary of Synchronization1. Laser vs Accelerator Synchronization System via Electronics
Picoseconds time-resolution
2. Laser Seeded Staged Accelerator
Femtoseconds time-resolution
Available for multibunches
3. Laser Plasma Accelerator
Beam Splitter enables even Attoseconds time-resolution
After Stable and reliable beam generation and diagnosis are established
Tens Femtosecond or Quasi-Monochromatic Electron Single Bunchby Laser Plasma Cathode (RAL, LBNL, LOA, AIST, U.Tokyo at AAC2004)
100
101
102
103
104
600 700 800 900 1000 1100 1200 1300
Inte
nsity
(arb
.uni
t)
Wavelength (nm)
1st-Stokes
Laser Wavelength
Tens femtoseconds
Quasi-monochromatic
U.Tokyo(cal)
AIST(exp)
AAC 2004 Experimental Results Laser-Plasma Accelerator WG
2 MeV
Self-trapped
1x101
8 cm-3
2TW0.8mkm
SM-LWFA
KERI
Glass capillary
100 MeV
Self-trapped
6x1016 cm-3
30TW1.06 mkm
LWFA
Osaka University
2 TW beam for LIPA injector
Ponderomotivechannel
Integrated over 90 shots spectrum
Channel
40 MeV20 MeV38 MeV40 MeV7 ±1 MeV2 pC
78 ±2MeV20 pC
86 ±2 -150 MeV300 pC
>170±15MeV, 500 pC,
Energy Gain
Self-trapped
OpticalInjection ioniz.
12 MeVexternal
Self-trapped
Self-trapped
Self-trapped
Self-trapped
Self-trappedInjector type
1.4x1020
cm-31x1019 cm-3
1x1016 cm-3
1.8x1019
cm-3.1.5x1020
cm-32x1019 cm-
32x1019 cm-3
6x1018 cm-3Plasm.Density
20TW0.8 mkm2.x1019 W/cm2W0=5 mkm,, 23fs
10TW1.06 mkm3x1018 W/cm2W0=12 mkm, 500s
1TW10.3+10.6.mk
6TW0.8 mkm1x1019 W/cm2W0=6 mkm,50fs
2TW 0.8 mkm5x1018 W/cm2W0=5mkm,50fs
16TW0.8 mkm ,1x1018 W/cm2W0=25 mkm,40fs
8TW0.8 mkm,1x1019 W/cm2W0=7 mkm, 55fs
30TW0.8 mkm, 3x1018 W/cm2,W0=18 mkm, 30fs
Laser parrs
SM-LWFA
SM-LWFA
PBWASM-LWFA
SM-LWFA
SM-LWFA
SM-LWFA
SM(for-ced)LWFA
Scheme
JAERINRLNeptune, UCLA
University of Tokio
AISTRAL-alphaX
LBNLLOA
