1 Accelerator Research Department B Accelerator Research Department B E163: Laser Acceleration at the NLCTA C. D. Barnes, E. R. Colby*, B. M. Cowan, R. J. Noble, D. T. Palmer, R. H. Siemann, J. E. Spencer, D. R. Walz Stanford Linear Accelerator Center R. L. Byer, T. Plettner Stanford University * Spokesman.
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E163: Laser Acceleration at the NLCTA - SLAC · 1 Accelerator Research Department BAccelerator Research Department B E163: Laser Acceleration at the NLCTA C. D. Barnes, E. R. Colby*,
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Accelerator Research Department BAccelerator Research Department B
E163: Laser Acceleration at the NLCTA
C. D. Barnes, E. R. Colby*, B. M. Cowan, R. J. Noble, D. T. Palmer, R. H. Siemann, J. E. Spencer, D. R. Walz
Stanford Linear Accelerator Center
R. L. Byer, T. Plettner
Stanford University
* Spokesman.
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Accelerator Research Department B
Outline• Introduction
–– Future requirements for high energy acceleratorsFuture requirements for high energy accelerators– High efficiency high gradient acceleration– Lasers as power sources for acceleration– Technical issues
• The E163 Proposal– Context– Experimental program– Facility requirements, construction, and cost
• Future Potential
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Accelerator Research Department B
Requirements for FutureHigh Energy Linear Colliders
Near Term:• Center-of-mass energy 0.5-1.0 TeV• Luminosity >1034 cm-2 s-1
Long Term:• >3 TeV and readily extendable• Luminosity >1035 cm-2 s-1 and increasing with �2
ILC
Compactness, power efficiency, and reliability
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Accelerator Research Department B
Requirements for high efficiency high gradient acceleration
Power efficiency improves with decreasing stored energyEcm – Collider’s center-of-mass energyG – Accelerator Gradient� – Acceleration field wavelength� – power source efficiency
cmG
ac EP��2
�
Resistance to breakdown and surface damage improve with decreasing pulse length:
• Less opportunity for plasma formation
• Less energy available to do damage
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Accelerator Research Department B
Requirements for high efficiency high gradient acceleration
High gradient, high efficiency acceleration requires a power source with high fluence and efficiency:
SOURCE FLUENCESOURCE FLUENCE
GP
cmacE 1
2�
���
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Accelerator Research Department B
Outline• Introduction
– Future requirements for high energy accelerators– High efficiency high gradient acceleration–– Lasers as power sources for accelerationLasers as power sources for acceleration– Technical issues
• The E163 Proposal– Context– Experimental program– Facility requirements, construction, and cost
• Future Potential
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Accelerator Research Department B
Coherent Sources of RadiationSource Frequency [GHz]
Sour
ce F
luen
ce [T
W/c
m2 ]
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Accelerator Research Department B
Efficiency of Power Sources
TUBES FEMs FELs LASERS(RF Compression, modulator losses not included)
– Future requirements for high energy accelerators– High efficiency high gradient acceleration– Lasers as power sources for acceleration–– Technical issuesTechnical issues
• The E163 Proposal– Context– Experimental program– Facility requirements, construction, and cost
• Future Potential
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Accelerator Research Department B
Phase-Locking of LasersDiddams, et al, “Direct Link between Microwave and Optical Frequencies with a 300 THz Femtosecond Laser Comb”, Phys. Rev. Lett., 84 (22), p.5102, (2000). [Figures below are from this reference]
R. Shelton, et al, “Phase-Coherent Optical Pulse Synthesis from Separate Femtosecond Lasers”, Science, 293, 17 AUG (2001).
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Accelerator Research Department B
Making Laser-driven Accelerator StructuresConventional waveguide structures scaled to optical wavelengths would:
•Have impossible machining tolerances (~�/1000)•Rapidly ablate if powered with lasers•Have very tiny beam holes (~�/10)
How can structures be made?
•By using fundamentally different kinds of structures: Quasioptics•By using fundamentally different means of fabrication: Lithography
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Accelerator Research Department BInterferometric Acceleration
Interaction Length : ~1000 ��~0.1 ZR
z
Terminating Boundary
E1
E2
E1zE2z
E1x
E2x
x
E1x + E2x = 0
|E1z + E2z| > 0
no transverse deflection
nonzero electric field in the direction of propagation
Slit Width ~10 �
Slit Width ~10 �
Electron beam
Waist size: wo~100 �
Crossing angle: �
Terminating Boundary
The laser beams are polarized in the XZ plane, and are out of phase by �
Effect of varying laser pulse durationLaser OffLaser On
5 �m slits, 2 ps Electron Beam
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Accelerator Research Department B
Making Laser-driven Accelerator Structures
Photolithography• A well-understood process widely used in industry• Feature sizes down to 130 nm can be reliably produced• A variety of materials and processes can be used• Highly complex structures can be made• Mass-production is cost-effective, even for complex designs• Extensive fabrication facilities are available at Stanford for
rapid prototyping
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Accelerator Research Department B
Large-Market TechnologiesU.S. Government, projected for 2002[1]:
Revenue: $2.1 trillionDOE and NSF: 3.2+4.5= $7.7 billion
Semiconductor industry, domestic, in 1999[2]:Revenue: $168.6 billionR&D: $22 billion
[1] “The Budget of the United States Government, FY2002”, OMB.[2] “Is Basic Research the Government’s Responsibility?”, Cahners Business Information, (2000).[3] J. Timmer, “Telecommunications Services Industry”, Hoover’s Business Network, (2000).[4] “International Science Yearbook 2001”, Cahners Business Information, 2001.
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Accelerator Research Department B
Outline• Introduction
– Future requirements for high energy accelerators– High efficiency high gradient acceleration– Lasers as power sources for acceleration– Technical issues
• The E163 Proposal–– ContextContext– Experimental program– Facility requirements, construction, and cost
Objective: To demonstrate laser driven electron acceleration in a dielectric structure in vacuum.
First funded by Stanford patent money, subsequently funded though the DOE-HEP office of Advanced Accelerator Research in 1997, renewed in 2000.
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Accelerator Research Department B
The LEAP Accelerator Cellcrossed
laser beams
electronbeam
Fused silica prisms and flats
High Reflectance Dielectric coated surfaces
Accelerator cell
slit
Computed Field Intensity, |Et|2
~1 cm
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Accelerator Research Department B
The LEAP Accelerator Cell
Electron Beam
1 cm
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Accelerator Research Department B
crossedlaser beams
electronbeam
accelerator
~ 1 cm
crossedlaser beams
electronbeam
crossedlaser beams
electronbeam
crossedlaser beams
electronbeam
accelerator
Imageintensifiedcamera
doped YAGscreen
spectrometermagnet
Diagnostics:•spatial monitor•streak camera
~ 1 m
Imageintensifiedcamera
doped YAGscreen
spectrometermagnet
Diagnostics:•spatial monitor•streak camera
The LEAP Experimental Setup
Camera
Electron beam
Vacuum chamber
cellcell
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Accelerator Research Department B
The Interaction ChamberBeam Direction
ABOVE: The single laser pulse is split into two pulses, delayed and reduced in size in this secondary vacuum chamber.
LEFT: The laser acceleration cell is mounted amidst diagnostics in this chamber.Laser profile, alignment, and slit width diagnostics are mounted in the foreground.
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Accelerator Research Department B
Precision Low-Charge Spectrometry
timeenergy
Intensity
2 keV (1:104) resolution spectrometry with sub-picoCoulomb beams
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Accelerator Research Department B
Laser and Electron Beam Timing and Position Overlap Diagnostics
pellicle YAG screenholder
Cerenkovcell
electronbeam
XYBION1SG350-U-E
HAMAMATSUC-1587
streakcamera
intensifiedgain camera
tiltstage
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Accelerator Research Department B
Laser Relative Phase Diagnostic
variable delay arm
fixed delay arm
piezocrystal
� = 180o
� = 0o acceleratorcell
leakage field
diffuserscreen
CCDcamera
Incoming laser pulse
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Accelerator Research Department B
Technical RoadmapLEAPLEAP
1. Demonstrate the physics of laser acceleration in dielectric structures 2. Develop experimental techniques for handling and diagnosing
picoCoulomb beams on picosecond timescales3. Develop simple lithographic structures and test with beam
E163E163Phase I. Characterize laser/electron energy exchange in vacuumPhase II. Demonstrate optical bunching and accelerationPhase III. Test multicell lithographically produced structures
Now and FutureNow and Future1. Demonstrate carrier-phase lock of ultrafast lasers [NIST, Stanford]2. Continue development of highly efficient DPSS-pumped broadband
mode- and carrier-locked lasers [DARPA Proposal, SBIR Solicitation]3. Devise power-efficient lithographic structures [SBIR Solicitation]4. Devise stabilization and timing systems for large-scale machine [LIGO]5. …
Dam
age Threshold Improvem
ent
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Accelerator Research Department B
Outline• Introduction
– Future requirements for high energy accelerators– High efficiency high gradient acceleration– Lasers as power sources for acceleration– Technical issues
• The E163 Proposal– Context–– Experimental programExperimental program– Facility requirements, construction, and cost
• Future Potential
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Accelerator Research Department B
Phase I: Laser Accelerationcrossed
laser beams
electronbeam
Fused silica prisms and flats
High Reflectance Dielectric coated surfaces
Accelerator cell
slit
Computed Field Intensity, |Et|2
Scientific Goals:•Thoroughly characterize the dependencies of the energy modulation on:
• Interaction length• Crossing angle• Slit width• Relative laser phase• Physical tolerances of the cell
Technical Goals:• Commission the experiment at the NLCTA•Make progress understanding electric field breakdown issues and the attendant design implications•Timing synchronization
E
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Accelerator Research Department B
Optical BunchingUNBUNCHED
BUNCHED
1 2
3 4
ENER
GY
PHASESimulation: GENESIS (S. Reiche) for 0.8��laser, 60 MeV electron beam
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Accelerator Research Department B
Phase II: Prebunch and AccelerateScientific Goals:• Demonstrate and quantify optical bunching• Demonstrate and quantify acceleration• Determine the impact of beam transport on bunching washout
Technical Goals:• Commission the IFEL prebuncher• Understand mechanical stability required to maintain attosecond-scale timing synchronism• Implement optical bunching diagnostics
E
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Accelerator Research Department B
STELLA (Staged Electron Laser Acceleration) experiment at the BNL ATF
Technical Goals:• Master lithographic production techniques for silica or silicon microstructures• Make progress understanding damage threshold issues• Fabricate integrated accelerator components• Devise and test methods of beam focussing
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Accelerator Research Department B
Outline• Introduction
– Future requirements for high energy accelerators– High efficiency high gradient acceleration– Lasers as power sources for acceleration– Technical issues
• The E163 Proposal– Context– Experimental program–– Facility requirements, construction, and costFacility requirements, construction, and cost
Why move the experiment to the NLCTA?LEAP has been hosted at HEPL for the last 4 years and has enjoyed their support. The lack of run time and marginal beam quality will not allow further progress on this experiment at HEPL. Additionally, the future of an accelerator facility on campus is in doubt, as Stanford Campus plans call for the renovation of Hansen and Ginzton Laboratories.
The experimental program described here will require more than two years to complete so the move to a facility with good beam quality and a long-term future is pressing.
The Advanced Accelerator Research Committee met in summer 1999 to examine facilities on the SLAC site for conducting advanced acceleration experiments and concluded that the NLCTA was the best location for such experiments.
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Accelerator Research Department B
E163 Layout at the NLCTA (from the Proposal)
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Accelerator Research Department B
NLCTA Injector Upgrade
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Accelerator Research Department B
Resource Requirement Summary
Total Materials and Services: $0.96M
9.4 FTE-years of SLAC Labor: $1.03M
Value of existing equipment that will be transferred to E163: $1.13M
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Accelerator Research Department B
E163 Labor Estimates
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Accelerator Research Department B
E163 Budget EstimateE163 Costs SLAC Labor
SLAC Labor
Cost to SLAC
Pre-existing
Pre-existing
hours k$ k$ LEAP E163Weighted Average Hourly Rate for Labor (not burdened) $62.21 ($110,000 for 1768 hours per FTE)
* We expect to scrounge this from SLAC Pre-exist** We expect to continue our long-term loan of this camera from Prof. S. Harris
•Pre-existing equipment values (columns 4 and 5 on the “E163 Costs” spreadsheet) are best-guess replacement costs.•Labor estimates are based on original ORION labor estimates, scaled to reflect the reduced scope of the E163 experiment.•Labor is valued at $110,000 per FTE per year, for a total of 1768 hours per year.•Cost estimates for equipment are best-guess, with the exception of the laser system, gun solenoid, and laser room, which are industry quotes.•Labor costs (e.g. for the modulator) assume assembly is from parts, with no large subassemblies available.•ARDB physicist labor costs are not included in the total estimated labor costs.
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Accelerator Research Department B
Summary Schedule for E163 Facility Construction
E163 Experimental Program Begins
NOW
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Accelerator Research Department B
Future Potential
The proposed E163 installation at ESB will be a versatile acceleration test facility developed at nominal cost using existing beam facilities at the NLCTA.
Picosecond electron and photon beams with very high energy densities are available together with diagnostics suitable for a broad range of picosecond time-scale experiments. Modularity and versatility have been preserved to insure the facility is broadly usable.
The E163 collaboration plans to make future applications to the EPAC to explore other lithographic accelerator structures.