Design and Experimental Considerations for Multi-stage Laser Driven Particle Accelerator at 1

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Design and Experimental Considerations for
Multi-stage Laser Driven Particle Accelerator at
1µm Driving Wavelength
ORION Workshop Feb.18-20,2003

• Y.Y. Lin(???), A.C. Chiang(???), Y.C. Huang(???)
• Department of Electrical Engineering, National
  Tsing Hua University, Hsinchu,300, Taiwan

NTHU Relativistic Photon-Electron Dynamics
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OUTLINE

• Motivation
• Review on the multi-stage CO2-laser-acceleration
  Project at ATF BNL
• Scaled to 1-µm Wavelength
• A Proposed Muti-stage Experiment at ORION

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MOTIVATION

• 10-µm Wavelength using 70 MeV beam at ATF BNL
• a. large structure size
• b. high-power CO2 laser available at ATF
• c. easier for alignment
• d. good for proof-of-principle experiment
• 1-µm Wavelength using 350 MeV beam at ORION
• a. higher material damage field with 1-µm
  wavelength
• b. higher laser damage threshold with 100 fs
  laser pulse
• c. smaller phase slip with 350 MeV beam
• d. smaller beam size for electron transmission
  aperture
• e. higher acceleration gradient
• f. solid-state laser stability and efficiency

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CO2-laser-acceleration Project at ATF BNL
Lens-array structure (I) Accelerating Stages
Laser beam waist 280µm
1.5cm
f5z0/33.81cm
Electron transit on each lens is 100µm in
diameter
2/3z0
24 cm 15cm x 16
Each lens temperature is varied independently by
a TE cooler
Ref E.J. Bochove, G.T. Moor, ad M. O. Scully,
Phy. Rev. A, Vo. 46, No. 10 ,pp. 6640-53,Nov. 1992
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CO2-laser-acceleration Project at ATF BNL
Phase offset
TEM00
W0 104 mm
Lens-array structure (II) System setup of the
multi-stage lens array accelerator structure
E_max132M V/m Energy gain240 keV
f10
100 mm
30.48 cm
W0 2000 mm
Chamber
f2
120 mm
f3
f0.5
Iris mirror
Accelerator cell
iris
W0 280 mm
Si detector (movable)
120 mm
24 cm
5.32 cm
9.19 cm
2 cm
48.15 cm
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Numerical simulation for 1st stage
CO2-laser-acceleration Project at ATF BNL
NTHU Relativistic Photon-Electron Dynamics
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Numerical simulation for 2nd stage
CO2-laser-acceleration Project at ATF BNL
NTHU Relativistic Photon-Electron Dynamics
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Lens-array structure (III) Energy Gain along axis
CO2-laser-acceleration Project at ATF BNL
Damage threshold 0.45 J/cm2 for ZnSe and 1.2
J/cm2 for CVD diamond Total energy Gain over 24
cm 240 keV (ZnSe)
400 keV (CVD diamond)
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Lens-array structure (IV) The Design Parameters
for the Multistage Accelerator at ATF BNL
CO2-laser-acceleration Project at ATF BNL
Single-stage length 1.5 cm
Total linac length 24 cm
Number of accelerator stages 16
Electron transit hole diameter 100 ?m
Laser beam waist in each stage 280 ?m
Laser damage threshold (ZnSe) 2.25 GW/cm2(0.45 J/cm2)
Laser wavelength 10.6 ?m
Laser Mode TEM01
Phase tuning by temperature p over 93?C
Total energy gain 240 keV
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Lens array structure at (V) Temperature phase
tuning
CO2-laser-acceleration Project at ATF BNL
B.S.
Mirror
laser
HeNe
Si detector (det210)
iris
L1
Mirror
B.S.
TE cooler
L1 ZnSe lens temperature controlled by TE cooler
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Lens array resonator structure at (V) Phase
tuning over temperature experiment
CO2-laser-acceleration Project at ATF BNL
,where d is the thickness of lens(0.98mm), and
?0 is the wavelength of He-Ne laser in vacuum
(632.8nm)
For 10.6 um
Or
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Scaled to 1 ?m wavelength at ORION
ORION ATF
Wavelength 1µm 10.6 µm
Beam energy 350MeV (?small phase slip and beam size) 70MeV
Laser pulse width 100 fsec 200 psec
Damage threshold 2J/cm2 0.45J/cm2
advantage suitable for high-gradient experiment Suitable for proof-of-principle experiment

1. Formation/coherence length ?2 ?
2. Acceleration field v(damage threshold)

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Lens-array structure (I) The Design Parameters
for the Multistage Accelerator
A Proposed Muti-stage Experiment at ORION
High-gradient, small structure design Low-gradient, large structure design
Single-stage length 1 mm 5 mm
Total linac length 1.3 cm 6 cm
Lp( Coherent length ) 9.8 mm 260 mm
Number of accelerator stages 13 12
beam waist (W0) 18.4 ?m( with zr1mm) 87.3 ?m ( with zr2.25cm)
Laser damage threshold 2J/cm2 2 J/cm2
Laser wavelength 1 ?m 1 ?m
Laser Mode TEM01 TEM01
Total energy gain 3.6 MeV 4MeV
Acceleration gradient 280 MeV/m 66 MeV/m
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A Proposed Muti-stage Experiment at ORION
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Summary Table of Laser Acceleration Project at
ORION (I)
A Proposed Muti-stage Experiment at ORION
Electron beam parameter
Energy 350MeV
Pulse length 100 fsec
Particles 109
Energy Spread 0.1
Normalized Emittance 1 mm-mrad
Timing Stability 100 fsec
Energy Stability 0.1
Pointing Stability 1µm
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Summary Table of Laser Acceleration Project at
ORION (II)
A Proposed Muti-stage Experiment at ORION
Laser beam parameters
Pulse Energy 0.3 mJ
Wavelength 1 µm
Pulse width 100 fsec
Mode TEM10
Timing Stability 100 fsec
Pointing Stability 1µm
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Summary Table of Laser Acceleration Project at
ORION (III)
A Proposed Muti-stage Experiment at ORION
Electron Beam Diagnostics
Energy Spectrometer 0.1
Charge 10 pC/pulse (108 electrons)
Positioning resolution 1 µm
Emittance resolution 0.05 µm rad
Pulse timing resolution lt 0.1 psec
Laser Beam Diagnostics power, pulse width,
wavelength etc.
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Summary

• The 1 MeV/m Multi-stage CO2-laser-acceleration
  Project at ATF BNL is a proof-of-principle
  experiment for vacuum acceleration
• ORION facility is suitable for high-gradient,
  small-size vacuum acceleration.
• With 350 MeV beam, 1 µm wavelength, and 100 fsec
  laser pulse width, an acceleration gradient of
  280 MeV/m can be obtained near the material
  damage.
• The electron energy gain from the proposed 14
  accelerator stages is 3.6 MeV over a overall
  accelerator length of 1.3 cm.

NTHU Relativistic Photon-Electron Dynamics
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