Advanced Accelerator Research

1
Advanced Accelerator Research Development at
JAERI-APRC
Kazuhisa NAKAJIMA KEK JAERI-APRC
2nd ORION WORKSHOP SLAC, Feb. 18-20, 2003
2
Japan Atomic Energy Research Center Kansai
Establishment Advanced Photon Research Center
Spring-8 in Harima
KEK in Tsukuba
Kyoto
Osaka
Tokyo
JAERI-KANSAI (West) in Kizu
??
Director Toshi Tajima
3
Colleagues of Laser Acceleration Research Group
Kazuhisa NAKAJIMA Masaki KANDO Hideyuki
KOTAKI Shuji KONDOH Shuhei KANAZAWA
Shinichi MASUDA Takayuki HONMA
4
Outline
Progress of laser-driven accelerators
Recent topics on laser-plasma electron sources
Facility for laser acceleration research at
JAERI-APRC
Recent results on laser-plasma acceleration Experi
ments
Prospects of laser accelerator developments
5
Direct Laser Field Accelerators
Particle velocity Phase velocity lt c
Inverse FEL
Inverse Cherenkov Accelerator
Grating Accelerator
Inverse Smith-Purcell Effect
Vacuum Beat Wave Accelerator
Ponderomotive accelerator
6
Laser-driven Plasma Wave Accelerators
Plasma Beat Wave Accelerator
Laser Wake-Field Accelerator
LWFA
PBWA
Self-Modulated LWFA
Solitary wake accelerator
SM-LWFA
vglt c
7
Progress of Laser Acceleration Experiments
Laser-plasma acceleration experiments
demonstrated gt200MeV, gt100GeV/m electron
acceleration.
1 PeV
Laser Ponderomotive Energy trend
Conventional accelerator energy frontier
1 TeV
Hadron colliders
Acceleration mechanism
Energy Gain
GeV Laser Acceleration at JAERI-APRC
ee- colliders
1 GeV
PWFA
SLAC
LULI
JAERI/KEK/UT
LLNL
ICF
UCLA
Michigan
KEK
RAL
PBWA
ILE
NRL
MPI
KEK/ILE
BNL
LWFA
1 MeV
LULI
SM-LWFA
ANL
1970
2000
2010
2020
1980
1990
Year
8
Gas-Jet Plasma Cathode Experiments
A table-top accelerator
Gas jet LWFA experiment at LOA
Self-Modulated Laser Wake-Field Acceleration
experiment at Univ. of Michigan
Forced Laser Wake-Field Acceleration (?)
experiment
(V.Malka et al.,SCIENCE,298,1596,2002)
9
Relativistic electron beam generation by
ultraintense laser-plasma interactions
Relativistic electron beam generation experiment
at Univ. of Tokyo
Laser pulse
Emax 40 MeV
5 TW, 50fs
Transverse emittance 0.05 pmmmrad
by T. Hosokai
Intensity 1.5x1019W/cm2
a0 3.0
High quality electron beam
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Facility for Laser Acceleration Research
CPA Tisapphire laser system
1 PW
Peak power 100 TW Pulse duration 20 fs
Laser
Laser transport
Microtron with photocathode RF gun
Beam energy 150 MeV Beam intensity 100
pC, 10-60 Hz Bunch duration 10 ps Norm.
emittance lt5 p mm-mrad
Electron Beam Injector
Beam line with laser energy modulation and
chicane section.
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CPA Peak Power Toward the Petawatt
Petawatt
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The 10-1000 TW Laser Systemat JAERI-APRC
1PW,25fs, 1Hz 100 TW, 20 fs, 10 Hz TiSapphire
Laser System at JAERI Advanced Photon Research
Center in Kyoto
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Laser Peak Intensity (Optical Measurements)
Spot Image
14
Schematic of the Petawatt TiSapphire System
45 mJ Green Pump
Oscillator 10 fs
Stretcher 1 ns
Regenerative Amplifier 8 mJ, 10 Hz
4-pass Preamplifier 320 mJ, 10 Hz
4-pass Power Amplifier 3.3 J, 10 Hz
3-pass Booster Amplifier 40 J, Single Shot
Compressor 25 fs, 28 J, 1.1 PW
6.4 J Green Pump
70 J Green Pump
Additions for the petawatt
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Major Petawatt Components
8 cm diameter Tisapphire disk
80-mm TiSapphire disk
40 cm compression grating
70-J green Ndglass laser
Petawatt vacuum compressor
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Offner Stretcher and Compressor with Mixed
Grating Scheme
J. Squier et al, Appl. Opt. ,vol. 37, 1638, 1998
1200 grooves/mm Offner Stretcher
Bandpass 100 nm
Dazzler (planned)
1480 grooves /mm Tracy Compressor
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Tables-Top Petawatt TiSapphire Laser System
Oscillator
Stretcher
Regen
Pre - amp
100TW compressor
Power - amp
Nd YAG
Nd glass
Booster - amp
PW compressor
Optical table size 90 m2
18
Pulse Compression and Beam Quality
Peak power
Autocorrelation trace
32.9 fs (FWHM)
0.55 PW
18.1 J (after compression)
Pulse duration 32.9 fs (FWHM)
Beam Quality (before compression)
Intensity (a. u.)
Horizontal plane 1.22 times diffraction limited
Vertical plane 1.15 times diffraction limited
Delay (fs)
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Laser Acceleration Test Facility
Commissioning in 2000
Radiation safety permission up to 2 GeV, 50 pA
150MeV Microtron
IFEL Undulator
100 TW Laser Pulse
Chicane
Plasma Waveguide
Electron Spectrometer
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High quality electron beam injectors
Photocathode RF gun Max. charge 3nC,
QE1.4x10-4, Rep. rate 50Hz, Stability lt1
150 MeV Microtron 25 laps, Magnetic field
1.23T Bunch length lt10ps Norm.emittance
lt5pmm-mrad Transmission efficiency lt 92
1.1 m
3.5 m
CCD Camera
150 MeV Photocathode - Microtron
Synchrotron radiation from an electron bunch in
Microtron
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Performance of Photocathode RF Gun
RF Cavity
RF
Number of cell


1.6
Peak power
8.6 MW
Cathode




Cu


Pulse duration
4 µs
Frequency



2856 MHz

Repetition rate
50 Hz
Shunt impedance

57 M?/m

Laser
Wavelength


263 nm
Energy



200 µJ
Energy stability

0.5
Pulse length


6 ps
Phase (deg.)
22
All-solid-state laser for photocathode RF gun
Oscillator





All-solid-state NdYLF Laser
SESAM mode-locked NdYLF













Wavelength
1053 nm
















Pulse length
12 ps (FWHM)



Repetition rate
79.3 MHz




Output power
gt 100 mW






jitter
0.39 ps
Timing Stabilizer
Phase locked loop with a reference signal
















Regen
Laser-diode pumped NdYLF
Output energy
2 mJ
Repetition rate
100 Hz (max.)
Frequency Conversion
Output




Green(527 nm)
SHG at 1053 nm

Output energy of UV



200 µJ


by KTP crystal

Energy stability of UV
lt 0.5






UV (263 nm)
SHG at 527 nm

6 ps

Pulse length of UV
by BBO


23
Beam charge and Transmission efficiency
Commissioning performance

• Charge 95 pC with 77 transmission and 4
  stability
• Transmission efficiency 92 for 68 pC
• Repetition rate 10 Hz

Transmission efficiency of the conventional
microtron with thermionic electron gun is less
than 10
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Electron beam line for laser acceleration
Bunch Slicing Chicane
IFEL Undulator
IFEL Modulation Pulse
Electron Spectrometer
Laser-Plasma Accelerator
100TW,20fs Laser Pulse
Final Focus Quads
Wake Pump Pulse
Focusing mirror
Chicane
Final focus spot size
H
H35mm V62mm
V
Undulator
Beam Envelope
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Laser and Beam Transports
Electron beam line
Laser transport
Acceleration chamber
Spectrometer
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Activities and Achievements
Brief History
1996
250 MeV LWFA experiment using 2TW, 90 fs T3
laser with 17 MeV electron linac beam injection.
Wakefield measurements by the frequency domain
interferometry. Ovservations of a long
self-channeling and abnormal blueshift.
1997
50 Hz Photocathode RF gun developments by
KEK/SHI/BNL
2 cm capillary discharge plasma waveguide
developments
1998
1999
150 MeV Photocathode-Microtron developments
2000
Laser Acceleration Test Facility developments
2001
20 GeV/m laser wakefield measurement in a gas-jet
plasma
The first gas-jet plasma cathode experiment
2002
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The world-highest laser acceleration
H. Dewa et al., NIM A410, 357, 1998 M. Kando et
al., JJAP, 38, L967, 1999
Measured energy gain spectrum
.
The world-highest energy gain of gt250 MeV has
been achieved by LWFA experiments using 2TW,
90fs T3 laser and 17 MeV electron linac.
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Schematic of Frequency Domain Interferometry
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Plasma density oscillation measured by frequency
domain interferometer
30
A long self-channeling and anomalous blue-shift
Thomson scattering image at 1.8 TW, 20 Torr (He)
Anomalous blue-shift spectrum at 20 Torr (He)
original
After propagation
Self-channeling length 2.5 cm
(J. K. Koga et al., Phys. Plasmas, 7, 5223,2000)
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Gas density measurement for laser-plasma
production
Gas Jet Gas N2 Backing Pressure 25atm.
Duration1msec Orifice 0.8mm IMAX(CCD) Gate
5msec
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Density measurement of the gas jet
Time-resolved gas jet density measurement
He gas density distribution
Gas jet nozzle 0.8 mm diam.
He gas
Gas N2
10 atm
Backing Pressure 25 atm
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Measurements of laser wakefields
Measurement of a laser wakefield excited by a 2
TW, 50fs laser pulse with frequency domain
interferometer
Ez 20 GV/m
(H. Kotaki et al., Physics of Plasmas Vol. 9,
1392, 2002.)
34
2-cm fast Z-pinch capillary optical guiding
The 2TW, 90fs laser pulse (gt 1x1017 W/cm2) has
been guided over 2 cm in a Z-pinch capillary
discharge plasma.
(T. Hosokai et al., Opt. Lett. 25,10, 2000)
Guided
Unguided
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Jitter-free discharge system of the plasma
waveguide
Marx Generator High voltage400kV High
impedance20W
Charging 10Hz
Water Capacitor High voltage400kV Low
inductancegt30nH High current60kA(3W) Fast
rising current15ns
Front view of water capacitor
Trigger
Multi Laser Trigger Spark Gap Low
jitter Cylindrical current flow
Electron beam
Stabilization of plasma channel
Laser trigger optics
36
Setup for the gas-jet plasma cathode experiment
37
Inside view of the acceleration chamber
Electron detectors Si(Li) , Faraday cup
Gas-Jet target 0.8mmf Laser Focus (spot 10mm)
Extracting OAP with a 5mmf hole
Off-axis parabolic mirror f180mm
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Measurement of pulse duration
Single-shot auto-correlation measurement
Pulse width 30 fs (FWHM)
39
Measurement of a spot size at focus
Peak focus intensity 7.3x1018 W/cm2 at 5 TW
RMS spot radius for 50 energy
Diffraction-limited focus for a He-Ne reference
laser
sx5.3mm, sy 3.5mm
RDL3.4 mm, R 2.5x3.1 mm
Focus for He-Ne 40mm diam.
40
Plasma and electron signals
62 mJ, I 2.4 x 1018 W/cm2, a01.1, ne 6.4 x
1019 cm-3
Focus at 0.29 mm downstream
Focus at the center of the nozzle
Focus at 0.77 mm upstream
Minimum energy 292keV
Minimum energy 168keV
Minimum energy -10keV
41
1D PIC simulation of electron acceleration
Laser pulse Duration 30 fs, Intensity
6.8x1018W/cm2 (a01.8)
Plasma density distribution
3.61019cm-3
2.41019cm-3
x
0.15mm
0.1mm
2mm
Accelerated electron bunch
42
Estimates of electron energy spectrum
1000
All angles
100
Number of electrons (/2.5106)
10
1
140
120
100
80
60
40
20
0
Energy MeV
Forward angle
-5.4 mradlt q lt5.4 mrad
43
Colliding pulse injection
Colliding pulse injection scheme
Simulation parameters
Pump pulse
Wavelength 800 nm
Intensity a01
Pulse duration 50 fs
Injection pulse
Intensity a1 0.3
Plasma density distribution in a gas jet
Pulse duration 50 fs
Plasma density
ne 71017 cm-3
44
Simulation results of colliding pulse injection
(1mm)
45
Quality of optically injected beam
Pulse shape
Beam divergence
sr 0.0064
st 7.7 fs
?umber of electrons a.u.
?umber of electrons a.u.
Time fs
Energy spectrum
?????????? ??????????bt
Ep 7.4 MeV
Beam radius
sr 15 mm
DE/Ep 3
26 pC
Charge
?umber of electrons a.u.
Peak current
1.3 kA
Normalized emittance
1 pmmmrad
Electron energy MeV
46
Optical Bunch Slicing Injection

• The energy of relativistic electron bunch is
  optically
• modulated with picosecomd synchronization.

• The sliced femtosecond electron beam will be
  injected into
• the correct accelerating phase of laser wakefild
  with femto-
• second synchronization.

47
The energy modulation scheme

• Inverse FEL mechanism at the resonance condition

Electron bunch
g
Laser pulse
B0
lL

• Laser Beat Wave Acceleration mechanism

Colinearly injected laser pulses of two different
frequencies generate accelerating beat wave
forces.
Laser beat wave
Electron bunch
No undulator!
48
Bunch slicing experiments for productionof
femtosecond synchrotron radiationat ALS, LBNL
(CERN Courier 40,6,pp.31-32,2000)
49
Electron acceleration by standard laser wakefield
Experimental parameters
Laser peak power
P 100 TW
Pulse duration
t 20 fs
Plasma density
ne 7 x 1017 cm-3
Focus spot radius
r0 15 mm
Acceleration energy gain
DW 2.4 GeV/cm
Relativistic self-channeling threshold
Pc 42 TW
50
Capillary Plasma Waveguide
51
Summary
Laser acceleration test facility (LATF) completed
the high quality electron beam injector
consisting of the 150 MeV photocathode- microtron
and the beam line for laser acceleration experimen
ts using the 10 TW-1000 TW femtosecond laser
pulses. The first gas-jet plasma cathode
experiment has generated a collimated
relativistic electrons (lt100 MeV)with a
relatively small energy spread. The facility
will be opened for advanced accelerator RD to
the world-wide community.