e163: laser acceleration at the nlcta - slac · 1 accelerator research department baccelerator...

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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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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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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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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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– Future requirements for high energy accelerators– High efficiency high gradient acceleration–– Lasers as power sources for accelerationLasers as power sources for acceleration– Technical issues



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Coherent Sources of RadiationSource Frequency [GHz]

Sour

ce F

luen

ce [T

W/c

m2 ]

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Efficiency of Power Sources

TUBES FEMs FELs LASERS(RF Compression, modulator losses not included)

Yb:KGd(WO4)2�=1.037��t=112 fsecPave=1.3 W�=28%

SLAC PPM Klystron�=2.624 cm�t=3 �secPave=27 kW�=65%

Source Frequency [GHz]

Sour

ce E

ffic

ienc

y [%

]

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– Future requirements for high energy accelerators– High efficiency high gradient acceleration– Lasers as power sources for acceleration–– Technical issuesTechnical issues



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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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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 �

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Accelerator cell Length: 1000 �m

0 200 400 600 800 1000 1200 1400 1600 1800 2000-50

0

50

100

150

200

energy gain (keV)

dis tance (microns0 200 400 600 800 1000 1200 1400 1600 1800 2000

-6

-4

-2

0

2

4

6x 10

8

dis tance (microns

electric field Ez (Volts/m)

longitudinal field

1000 10002000 20000 0distance (�m) distance (�m)

0

100

200

ener

gy g

ain

(keV

)

0

2

4

6

-4

-2

�108

elec

tric

field

Ez

(V/m

) potential

|ET|2 map

Example: �=0.8� slit =16 �m, wo = 50 �m, � = 20 mrad

16�m slit

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Effect of varying slit width

Slit: 5 �m Slit: 10 �m Slit: 20 �m

-40 0 40 -40 0 40 -40 0 40Energy Modulation (keV)

Laser OffLaser On

5 psec laser pulse, 2 ps electron beam

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Effect of varying laser pulse durationLaser OffLaser On

5 �m slits, 2 ps Electron Beam

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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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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

Telecommunications industry, worldwide, proj. for 2001[3]:Revenue: $1 trillion (including services)R&D: $25 billion [4] (top 30)

Laser machining & welding, $30 billion/year � laser diode bars

[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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– 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


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The Laser Electron Accelerator ProjectLEAP

SLAC: R.H. SiemannJ.E. SpencerE. ColbyC. BarnesB. Cowan

HEPL: T.I. SmithR.L. Swent

GinztonLabs: R.L. Byer

T. Plettner

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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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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The LEAP Accelerator Cell

Electron Beam

1 cm

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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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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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Precision Low-Charge Spectrometry

timeenergy

Intensity

2 keV (1:104) resolution spectrometry with sub-picoCoulomb beams

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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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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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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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• The E163 Proposal– Context–– Experimental programExperimental program– Facility requirements, construction, and cost


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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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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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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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STELLA (Staged Electron Laser Acceleration) experiment at the BNL ATF

CO2 laser beam

ELECTRONSPECTROMETER

IFELACCELERATOR IFEL

BUNCHER

46 MeV 0.5 nC 2 mm mrad 3.5 ps

0.6 GW, 180 ps

Steeringcoil

BPM

BPM

BPM

BPM

Focusingquadrupoles

Steeringcoil

Focusingquadrupoles

Source: W. Kimura, I. Ben-Zvi.

Incoming e- beamOptically

bunched beam

Optically accelerated beam

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Phase III: Multicell Structures

Scientific Goals:• Demonstrate multi-stage acceleration of optically bunched beam•Quantify micropulse wakefields

E

Incoming plane waves

Lenslet Array

Phase Control

Lenslet Array

Electron beam

Electron beam

Transmission Mode Structure

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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• The E163 Proposal– Context– Experimental program–– Facility requirements, construction, and costFacility requirements, construction, and cost


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Experimental Requirements

Parameter Value Comment Electron Beam Properties

Bunch Charge 50 pC Beam Energy 60 MeV Transverse Emittance < 2.5 � mm-mr Normalized Bunch Length < 5 ps FWHM Energy Spread < 20 keV FWHM Pulse Repetition Rate 10 Hz

Laser Beam Properties (for experiment) Pulse Energy 1 mJ Pulse Wavelength 800 nm Pulse Length 0.1-10 ps FWHM, variable Pulse Repetition Rate 10 Hz Timing jitter w.r.t. electron beam < 1 ps

Present Valuesat HEPL

5 pC28 MeV

10 � mm-mr~5 ps

~20 keV10 Hz

1 mJ800 nm

1.0-10 ps10 Hz<3 ps

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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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E163 Layout at the NLCTA (from the Proposal)

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NLCTA Injector Upgrade

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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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E163 Labor Estimates

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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)

E163 Shielding EnclosureRelocate utilities at penetration 1Core drill extraction line 2.5Concrete-material cost 31Structure assembly 14Electrical Installation 22Plumbing Installation 5Cabling, Racks, Cable Trays 22PPS, MPS, BCS 20Total Estimated Labor 450 28

E163 Beamline ComponentsVacuum system 20 202 Bending dipoles 1512 air-cooled quads 506 steering magnets 3 3Spectrometer magnet 150Optical bunching wiggler 20Diagnostics 20 5Power Supplies for magnets 40*Total Estimated Labor 2362 147

E163 Experimental ApparatusInteraction Vacuum Chamber and Hardware 20 70Optical Table 8Micropositioning systems+movers 4Mirror positioners and controller 1010 CCD Video Cameras 42 Xybion Cameras 40PI*MAX Camera 40Picosecond Timing System 10Streak Camera C1587** 200Total Estimated Labor (ARDB personnel)

E163 Data Acquisition RoomNanosecond Timing Electronics, Scopes, etc. 50Move E-162 Trailer and reconnect electricity 8Total Labor Estimate (ARDB Personnel)

InjectorGun 7.7 9.7Solenoid 12.4 5Diagnostics 28 15.2Total Labor Estimate 3045 189

Laser RoomConstruction 100Optical Transport lines to gun and experiment 20 60Total Labor Estimate 80

Laser SystemOscillatorAmplifier 150DiagnosticsOptical components 10 10Optical TablesTotal Labor Estimate 1230 77

S-Band RF Power SourceKlystron, Pulse transformer, & Solenoidmodulator 100LLRF 25Waveguide 50Total Estimated Labor 6293 391

Utilities and ServicesB&H 50Access and Penetrations 5Total Labor Estimate (Included elsewhere in specific catagories)

Control SystemElectronics 50Total Labor Estimate 817 51

PPS, MPS, BCSFast-closing gate valve 18Electronics and Detectors 50Total Labor Estimate (From 98 SSRL Estimate) 2360 147

Totals (k$) 16637 1030 957.6 676hours k$ k$ k$LABOR LABOR M&S LEAP

* 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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Summary Schedule for E163 Facility Construction

E163 Experimental Program Begins

NOW

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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.

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Multicell Structure Concepts

Electron beams

TIR Silicon at 1.06 �

TIR Fused Silica at 1.06�

TIR Silicon at 2.5�

e163: laser acceleration at the nlcta - slac · 1 accelerator research department baccelerator...

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