A Laser Driven Linear Accelerator: Byer a Pathway Toward Attosecond Coherent X-Rays Group

A Laser Driven Linear Accelerator: Byer A Pathway Toward Attosecond Coherent X-rays Group

Robert L. Byer, Tomas Pletter, Eric Colby, Ben Cowan, Chris Sears, Jim Spencer and Robert Siemann

Department of Applied Physics SLAC Stanford University [email protected]

ABSTRACT

In 1947 W. W. Hansen and colleagues accelerated electrons with microwaves generated from a Klystron. That work led to the 3km linear accelerator at the Stanford Linear Accelerator Center completed in 1968.

In November 2005 we successfully accelerated electrons with a visible modelocked laser source. Today we are conducting experiments at SLAC to develop photonic bandgap dielectric based accelerator structures to efficiently couple laser radiation to electrons. The dielectric structures allow laser accelerators to operate at accelerating gradients of 1GeV/meter.

We have explored the possibility of laser accelerator driven coherent X-rays using a free electron laser. The approach looks promising because of the replacement of the traditional magnet based undulator with a laser driven dielectric based undulator. Progress toward the accelerator and coherent X-ray source will be discussed.

Panel on Light Source Facilities National Science Foundation Lawrence Livermore National Laboratory Wednesday 9 January 2008

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Contents Byer Group

Historic Background The Klystron and the Linear Acceleration of electrons Stanford Linear Accelerator Center – SLAC

The TeV-Energy Physics Frontier

Laser Electron Accelerator Project – LEAP HEPL Experiments from 1997 – Nov 2004 E163 Experiments at SLAC Laser accelerator structures Inverse FEL for electron pulse compression - <1 fsec electron pulse duration

Coherent X-ray laser Generation Components of the X-ray laser Dielectric Accelerator and Undulator Structures FEL gain and efficiency

Future Challenges Toward Table top Synchrotron sources

“Don’t undertake a project unless it is manifestly important and nearly impossible.” Edwin Land – 1982

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory The development of the linear accelerator at Byer Stanford University Group

“we have accelerated electrons” r Hansen's report to the Office of Naval Research r UEdr=⋅∫ The Mark III A high-energy physics research tool

1953: 400 MeV 1955: 600 MeV 1960: 1 GeV

Meson Physics carried out by W. K.H. Panofsky

High resolution electron scattering from nuclei by Robert Hofstadter 1947: The Mark I, 1m, 6 MeV

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer The Klystron tube Group

The “Microwave” Lab (Now HEPL and Ginzton Labs) played a crucial role on the development of particle accelerators and the corresponding RF technology

Ed Ginzton Marvin Chodorow & Klystron W. W. Hansen – back right

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer SLAC: The two-mile accelerator Group

“Project M” 1955 first brainstorming and informal discussions

• $100M proposal First beam at SLAC, 1966 • numerous studies and reports • > 10 years of effort

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Particle accelerator research at Stanford Byer Group

st 1st Klystron (Varian, 1930s’) 1 Linac 1946 The superconducting linac In HEPL, 1960

The 2-mile collider (SLAC)

LEAP, 1997-2004

Demonstration of the FEL, 1977

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 6 Byer SLAC – Particle Physics, Astrophysics Group & Photon Science

1968: First evidence of Quarks 1974: Discovery of the ψ particle 1976: Discovery of the charm quark and the τ lepton 1997: The BaBar experiment 2006: LINAC coherent X-ray source

Other developments • SSRL user facility • Computer science, software • KIPAC Particle Astrophysics

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory The Livingston plot – 1954 Byer Innovation leads to exponential progress Group

In 1954 Livingston noted that progress in high energy accelerators was exponential with time.

Progress was marked by saturation of the current technology followed by the adoption of innovative new approaches to particle acceleration.

Laser sources coupled with related technologies enable new approaches to Advanced Electron Accelerators.

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Contents Byer Group

Historic Background

The TeV-Energy Physics Frontier

Laser Electron Accelerator Project – LEAP HEPL Experiments from 1997 – Nov 2004 E163 Experiments at SLAC Laser accelerator structures Inverse FEL for electron pulse compression

Coherent X-ray laser Generation Components of the X-ray laser Dielectric Accelerator and Undulator Structures FEL gain and efficiency

Future Challenges Toward Table top Synchrotron Sources

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Group What is next?

Future TeV e+e- collision historical trend of high energy experiments

physics experiments CERN LHC • Top Quark Physics confirmation of the Z,W • Higgs Boson Searches and Properties particles 1 TeV first artificial discovery antiproton • Supersymmetry of the J/ψ production particle discovery discovery of the • Anomalous Gauge Boson Couplings of pions top quark discovery of the muon • Strong WW Scattering 1 GeV • New Gauge Bosons and Exotic Particles discovery CP violation discovery of of the Υ Experiment the neutron discovery BaBar - - - collision energy particle •ee , e γ, and γγ interactions of the τ particle discovery of the electron-nucleus • Precision Tests of QCD atomic nucleus 1 MeV scattering experiments radioactive sources, cosmic rays proton beams The NLC ZDR Design Group and the electron beams NLC Physics Working Groups Snowmass `96 workshop 1910 1920 1930 1940 1950 1960 1970 198 0 1990 2000 year

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Existing and Proposed Linear Accelerators Group

3 km

33 km

Existing SLAC – 50 GeV Proposed ILC Accelerator 1 TeV The goal of the Laser Electron Accelerator Program – LEAP - is to invent a new approach that will allow TeV physics on the SLAC site.

To achieve the goal we need an acceleration gradient of 1 GeV per meter.

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Introduction Introduction Group

Laser-driven particle acceleration • Idea came about soon after the invention of high- peak power lasers (earliest articles go back to 1971)

• different laser particle acceleration concepts ¾ ponderomotive ¾ linear electric field ¾ inverse cherenkov ¾ inverse FEL ¾ active gain medium ¾ laser driven plasma wakefield ¾ …

• experimental demonstrations are fairly “recent”

• very controversial topic

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Laser Driven Plasma Wakefield Acceleration Byer Group

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Principle of the Wakefield Accelerator Byer Group

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Wakefield Accelerator as a Booster for SLAC Byer Group

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Linear accelerators - accelerating relativistic Byer electrons Group

A few rules of the game

“An accelerator is just a transformer” – Pief Panofsky “All accelerators operate at the damage limit” - Pief “To be efficient, the accelerator must operate in reverse” -Ron Ruth, SLAC “ It is not possible to accelerate electrons in a vacuum” Lawson - Woodward theorem

“An accelerator requires structured matter – a waveguide - to efficiently couple the field to the electrons” anon

0 eV 100 keV ~ 2 MeV ∆U ≤ 50 MeV/m ∆x

electron DC potential RF modulator pre-accelerator accelerator structures source (buncher) β →1 β = 0 β ~ 1 2 1974 –sabbatical leave, Lund 1994 – SLAC summer school 2004 – Successful 1st Exp

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Emergence of new technologies make Byer Laser Acceleration Possible Group

efficient pump high power diode lasers Leveraging fiber lasers ALABAMA investment in LASER

telecom NUFERN

ultrafast laser sodium technology yellow

30 W/bundle, 40% electr. efficiency IMRA mJ 500 60 W/bar, 50% < 10 fs fsec laser electr. efficiency

nanotechnology new materials

high strength magnets Nd:Fe New ceramics

nano- tubes

high purity optical materials and high strength coatings

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 17 Schematic of Future TeV scale Laser Accelerator Byer Group

Proposed layout of the laser Master oscillator electron beam system for a TeV collider cavity length, accelerator dispersion control cell array A low-power ultra-stable master oscillator serves as a reference clock modelocked laser mode converter amplifier for the entire accelerator accelerator cell array

amplifier local modelocked oscillators are phase-locked to the master oscillator accelerator cell array

amplifier

A mode converter transforms the cavity length, accelerator dispersion control cell array TEM00 mode preferred by the laser to a TEM01 acceleration mode modelocked laser mode converter amplifier

accelerator cell array Laser amplifiers increase the amplifier power of the TEM01 mode from sub- watt to multiple tens of watts of accelerator average power cell array mode reference beam amplifier

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Laser beam parameters for TeV scale accelerator Byer Group

• Take advantage of high laser 2. Low bunch charge repetition rate problem • Multiple accelerator array architecture

Laser pulse structure that leads to high electron bunch repetition rate

4 10 laser pulse trains per second laser pulse laser- SLC NLC SCA-FEL TESLA accelerator laser pulse laser pulse train 4 optical cycle f RF (GHz) 2.856 11.424 1.3 1.3 3×10

4 f m (Hz) 120 120 10 4 10

4 N b 19510 4886 10

-6 ∆tb (nsec) -2.884.71763×10

2 4 5 4 6 fb (Hz) 1.2×10 1.1×10 1×10 1.6×10 3×10 electron bunch 10 9 7 10 4 Ne 3.5×10 8×10 3.1×10 1.4×10 10 10 laser pulses per laser pulse I (sec-1) 12 13 12 19 10 train e 4×10 9×10 3×10 2×10 3×10

Requires 10kW/meter or 10MW/km at ~40% efficiency Laser Source! •electric field cycle frequency Dramatic increase of •macro pulse repetition rate

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Atto Second Electron Bunches Group

1 degree of optical phase

electron bunch ∆x =15 nm, ~104 e-/ ∆t = 14 attosec bunch

laser beam

λ =1.5 µm, τ = 5 fsec

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Contents Byer Group

Historic Background

The TeV-Energy Physics Frontier

Laser Electron Accelerator Project – LEAP HEPL Experiments from 1997 – Nov 2004 E163 Experiments at SLAC Laser accelerator structures Inverse FEL for electron pulse compression

Coherent X-ray laser Generation Components of the X-ray laser Dielectric Accelerator and Undulator Structures FEL gain and efficiency

Future Challenges

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Laser Electron Accelerator Project - LEAP Group

Laser driven particle acceleration

collaborators

ARDB, SLAC Bob Siemann*, Bob Noble†, Eric Colby†, Jim Spencer†, Rasmus Ischebeck†, Melissa Lincoln‡, Ben Cowan‡, Chris Sears‡, D. Walz†, D.T. Palmer†, Neil Na‡, C.D Barnes‡, M Javanmarad‡, X.E. Lin† Stanford University Bob Byer*, T.I. Smith*, Y.C. Huang*, T. Plettner†, P. Lu‡, J.A. Wisdom‡

ARDA, SLAC Zhiu Zhang†, Sami Tantawi†

Techion Israeli Institute of Technology laser on Levi Schächter*

UCLA J. Rosenzweig* FWHM energy energyspreadspread FWHM FWHM (keV) (keV)

laser off laser timing (psec) ‡ grad students † postdocs and staff * faculty Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Participants in the LEAP Experiment Group

2 Bob Siemann2 Chris Sears Ben Cowan2 Jim Spencer2

New students •Chris Mcguinness2 •Melissa Lincoln2 •Patrick Lu1

Atomic Physics collaboration Tomas Plettner1 Eric Colby2 Bob Byer1 •Mark Kasevich3 3 1 E.L. Ginzton Laboratories, Stanford University •Peter Hommelhoff 2 Stanford Linear Accelerator Center (SLAC) •Catherine Kealhofer3 3 Department of Physics, Stanford University

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Laser acceleration – Dielectric structure Byer means high acceleration gradient Group

1 Energy gain through longitudinal electric field • gradient = longitudinal electric field linear particle • linear e-beam trajectory ∆UEdz=⋅ acceleration Æ no synchrotron radiation ∫ z Æ energy scalable process 2 Dielectric based very high peak structure with electric fields

vacuum channel 10 E s → 10 Vm vacuum Gradient→ 1 GeV m channel metals

NIR solid- 3 Inherent attosec state lasers 3 ~ 2 m, T~ 6.6 fsec λ µ

electron pulse electric field

1° of optical phase Unique T~ 20 attosec opportunity for 2 µm laser Æ 6 fsec period light sources Æ 1deg of phase = 20 attosec electron bunch

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory The proof-of-principle experiment Byer Group

HEPL beam parameters Beam Energy ~30 MeV amplified laser LEAP Telectron ~2 psec Charge per bunch ~5 pC area Energy spread ~20 keV

λlaser 800 nm Elaser 1 mJ/pulse

superconducting FEL collimator accelerator structures wiggler slits kicker

material laser boundary beam 8 µm Kapton 1 µm Au

Ez θ

electron electron beam 0 beam ∆UEdz= z ∫−∞

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory LEAP Experimental Success- November 2004 Byer Group

We have accelerated electrons with visible light!

laser beam

accelerating phase

electron decelerating beam phase

8 µm thick gold- tape coated Kapton tape drive stepper motors Inverse laser FEL electron beam beam The simplified single stage The LEAP experimental apparatus that Accelerator cell that uses Includes the LEAP single stage accelerator gold coated Kapton tape cell and the inverse FEL. to terminate the Electric field.

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Tomas Plettner and LEAP Accelerator Cell Byer Group

The key was to operate the cell above damage threshold to generate energy modulation in excess of the noise level.

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Accelerated electrons – key experimental results Group

0.05 0.1 0.2 0.3 0.4 Laser Pulse Energy (mJ/pulse) (keV)(keV) 〉〉 (keV)(keV) 〉〉 MM

〈〈 M simulation model MM 〈〈 M data

laser on M = 0.361⋅ E model z

M = ()()0.349±0.017 ⋅Ez − 0.35±0.25 AverageAverageModulationModulation Energy Energy Average Energy Modulation Modulation Modulation AverageAverage Energy Energy FWHM energy energy spread spread (keV) (keV) FWHM FWHM

Peak Longitudinal Electric Field Ez (MV/m) laser off Laser Polarization Angle θ (degrees) laser timing (psec)

+∞ • confirmation of the Lawson-Woodward Theorem Edz= 0 ∫ z −∞ laser-driven • observation of the linear dependence of energy gain linear ∆UE∝ laser with laser electric field acceleration in vacuum

• observation of the expected polarization dependence EEzlaser∝ cos ρ

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Energy Modulation vs Laser Peak Electric Field Byer (This is a modest laser with ~200 micro Joules in 4psec) Group

Laser fluence (J/cm2) 0.2 0.6 1.4 2.5 3.9

16 18 72 162 284 448 Laser pulse energy (µJ) 14

10 The acceleration is linear with the applied laser field 8 as expected from theory.

6 λ = 800 nm 4 TFWHM = 4.0 psec

Average modulation strength (keV) Α =100 µm 2 FWHM

0 00.511.522.5 Laser peak electric field (GVolt/m)

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 2nd Success: Visible light driven IFEL Byer Group

Cross-correlation in time Observation of harmonic interaction

* graduate student C.M. Sears

AARD subpanel Dec 21, 2005 Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 30 Contents Byer Group

Historic Background

The TeV-Energy Physics Frontier

Laser Electron Accelerator Project – LEAP HEPL Experiments from 1997 – Nov 2004 E163 Experiments at SLAC Laser accelerator structures Inverse FEL for electron pulse compression

Coherent X-ray laser Generation Components of the X-ray laser Dielectric Accelerator and Undulator Structures FEL gain and efficiency

Future Challenges

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer The E163 experiment at SLAC Group The NLCTA Next Linear Collider Test Accelerator 360MeV The new E163 experiment hall - 2005

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Group

60 MeV 10 pC ~ 1psec

λ = 800 nm U ~ ½ mJ/pulse τ ~ 200 fsec

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory GOAL: Invent and Test Accelerator structures Byer Group

Photonic bandgap fiber structures 2 and 3-D photonic bandgap structures

Current experimental fiber accelerator structure research Planar waveguide structures

R. Ischebeck, R. J. Noble, B.Cowan*, M. Lincoln*,C. Sears* *grad. students

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 34 Goal: Develop Theory for laser accelerator physics Byer Group

Energy efficiency of laser accelerators, single and multiple bunch operation

Coupling Efficiency vs bunch charge Beam loading calculations vs N

optimum efficiency about 1 fC

N (Number of bunches)

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 35 Byer Many possible dielectric microstructure architectures Group

Planar waveguide structures Periodic phase modulation structures

cylindrical cylindrical vacuum lens lens channel laser beam

top view

z electron λ/2 beam y x λ Z. Zhang et al. Phys. Rev. ST AB 8, 071302 (2005) T. Plettner et al, Phys. Rev. ST Accel. Beams 4, 051301 (2006)

Hollow core PBG fibers 3-D photonic bandgap structures

X.E. Lin, Phys. Rev. ST Accel. Beams 4, 051301 (2001) B. M. Cowan, Phys. Rev. ST Accel. Beams , 6, 101301 (2003). Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Transverse pumped grating phase-reset structure Byer Group

Main concept: quasi phase-matching of the EM field

perspective view top view traveling electron experiences vacuum accelerating force at all times channel dielectric structure laser beam t = 0 e

λ/2

τ laser z t = e electron 2 beam y x λ/2

λ T. Plettner et al, Phys. Rev. ST Accel. Beams 4, 051301 (2006) Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Transverse pumped phase-reset structure Byer Group

EM field map in one unit vacuum channel width < λ

vacuum channel

electron beam

r 1 E|| ~ 2 Elaser dielectric structure 1 J/cm2 fluence ~10 fsec pulses E|| input laser wavefront Gunloaded ~ 4 GeV/m r F⊥ = 0

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory The expected maximum gradients Byer Operate at the Breakdown Limit Group

a) b) r G⊥,TE ~ 0.15 Elaser x Ewall Elaser y 2 r z dielectric G||,TE ~ 0.3 Elaser l w vacuum ÷ 2 electron bunch U V 1 r dielectric U V G⊥,TE ~ 0.07 Emax laser beam 0 r G||,TE ~ 0.15 Emax λp

10 fsec laser pulse

G||,TE ~ 4 GV/m 2 1 J/cm Emax ~ 25 GV/m G ~ 2 GV/m (At breakdown limit) ⊥,TE

Y. Min Oh et al, International Journal of Heat and Mass Transfer 49 (2006) 1493–1500 B. C. Stuart et al, Physical Review Letters 74, 2248 (1995) M.Panel Lenzner on Light et al,Source “Femtosecond Facilities, National Optical Sc Breakdownience Foundation in Dielectrics”, Wednesday Phys. Rev. 9 January Lett. 80,2008 4076 (1998) Lawrence Livermore National Laboratory The most simplistic wakefield picture Byer The accelerator operates in reverse Group

Assume a “perfect” dielectric (real index of refraction) Æ The loss factor mechanisms come from diffraction

fwd. Smith-Purcell [1]

a)4πx0 λ p ~ 1 γ KC ~ 100 GeV/m/pC b)

2 10102

SP2

1 1010 G||,TE ~ 4 GV/m

0 x0 SP1 10100 40 fC qb

-1 1010-1 decelerationdecelerationdeceleration gradient gradient gradient (GeV/m) (GeV/m) (GeV/m) -2-2 1010 λ -4 -3 -2 -1 0 p 0.110 101 10 1010 2 10103 bunch charge (fC)

DL 2 2 but I have neglected the broadband beam loading [2,3,4] qV = (EL − ()EL + EW )τ L 2Z 0 Cherenkov wake…

[1] Phys. Rev. Lett. 74, 3808 (1995) KC ~ 100 GeV/m/pC [2] Phys. Rev. STAB 6 02441 (2003) [3] Phys. Rev. STAB 9, 111301 (2006) [4] Phys. Rev. STAB 7, 061303 (2004) Qb ~ 20 fC Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Transverse pumped phase-reset structure Byer Goal: test this structure at SLAC Group

2 cm 1 mm

electron beam to the energy 60 MeV spectrometer

laser beam

focusing triplet fabricated by graduate student P.P. Lu a) b)

fabricated by graduate student C.M. Sears Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Present experiment at E163 Byer Group Micro-bunching of a 60 MeV electron beam at 800 nm from a 3-period IFEL (Principal author: Chris Sears)

laser PMT

800 nm 400 nm filter

optical compressor buncher chicane

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Present experiment at E163 Byer Preliminary results provided by Chris Sears Group

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Near-future experiment at E163 Byer Group Observation of wakefields of the microbunched beam from a quartz grating Æ Beam position diagnostic Æ Inverse process of laser acceleration from the grating

laser PMT

800 nm 400 nm filter

pellicle optical compressor buncher chicane quartz grating

400 nm filter

PMT

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Near-future experiment at E163 Byer Group Laser-acceleration from a quartz-based mm-long accelerator microstructure

2 cm 1 mm

electron beam to the energy 60 MeV spectrometer

laser beam

focusing triplet fabricated by graduate student P.P. Lu a) b)

fabricated by graduate student C.M. Sears Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Future Experiments Byer Goal: test multiple stage acceleration Group

Cascading of microstructure accelerators

electron to the energy beam spectrometer 60 MeV

focusing triplet

laser ShowShow scalability scalability beam beam splitter phase Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermoredelay National Laboratory Contents Byer Group

Historic Background

The TeV-Energy Physics Frontier

Laser Electron Accelerator Project – LEAP HEPL Experiments from 1997 – Nov 2004 E163 Experiments at SLAC Laser accelerator structures Inverse FEL for electron pulse compression

Coherent X-ray laser Generation Components of the X-ray laser Dielectric Accelerator and Undulator Structures FEL gain and efficiency

Future Challenges

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Coherent picosecond X-ray wavelength sources Byer LINAC Coherent Light Source – at SLAC Group

RF-accelerator driven SASE FEL facilities - 2009

SASE-FEL 14 GeV

T ~ 230 Æ1 fsec LCLS properties λ ~ 1.5 – 15 Å Φ ~ 1012 γ / pulse 100 m • km-size facility • materials science •chemistry • microwave accelerator •atomic physics • ~ 10 cm accelerator λRF 3 km • 4-14 GeV e-beam LCLS injector • 120 m undulator • 23 cm period undulator • 15-1.5 A radiation 120 m • 0.8-8 keV photons •1014 photons/sec Experiment SSRL lines • ~77 fsec

• separate user lines • 120 Hz pulse train TTF: Tesla Test Facility; fsec EUV SASE FEL facility XFEL: Proposed future coherent X-ray source in Europe…

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory The Key Components of the SASE-FEL architecture Byer SASE – Self Amplified Spontaneous Emission Group

accelerator 3 km LCLS injector

undulator 120 m

Experiment SSRL lines

source of free accelerator undulator particles section

laser-driven dielectric structure dielectric structure, high rep. rate based laser-driven laser driven very compact particle accelerators Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Motivation for an FEL application Byer Attosecond Physics at hard X-ray energies Group

~ 1 GeV/m gradient GeV electron beam in 1-2 m

Short undulator Æ preserve the Few-attosec pulse structure few-attosec pulse structure on the photons

Possibility for MHz rep. rate Modelocked lasers and low- power amplifiers

SuitableSuitable electronelectron injectorinjector Requirements: MatchingMatching shortshort undulatorundulator

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Architecture of a laser-driven free-electron X-ray source Group

solid state, • sub-kW of electrical power tabletop • no radiation or electrical hazards λ ~ 1 µm • MHz repetition rates laser system ultra short pulses high peak electric fields

optically bunched electrons x-rays Source of free Accelerator undulator particles section

MEMs-based laser- Laser-driven field MEMs-based laser- driven dielectric emission sources driven dielectric accelerator structure deflection structure

total length on the order 1 m

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Development of the three key laser-driven components Group

source of free accelerator undulator particles section

develop a compact laser- driven electron injector Objective: 1. High rep. rate 2. Low power consumption 3. Ultra low emittance (~10-9 m-rad) 4. ~10 MeV in a few-cm structure

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer A conventional electron injector Group

a room full of lethal and bulky equipment…

The NLCTA accelerator front end

The klystron •~2 m tall • 1/3 MV ! • high power • water cooling • X-ray radiation • 10 Hz rep. rate

RF cathode

temporary source of relativistic electrons for present laser-acceleration experiments Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer A laser-driven field-emission free-electron source Group

P. Hommelhoff et al, Kasevich group

laser Field emission tip properties beam 1. laser-assisted tunneling of electrons from the atom to free space 2. Highly nonlinear 3. Potential for timed sub-optical field emitter cycle electron emission tip

metal vacuum −10 εtip ~ 10 m − rad

P. Hommelhoff, Y. Sortais, A. Aghajani-Talesh, M. A. Kasevich, “Field Emission Tip as a Nanometer Source of Free Electron Femtosecond Pulses”, PRL 96, 077401 (2006)

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Addition of a low-energy laser-accelerator cell Group

Collaboration work with the Kasevich group objectives Laser 1. multiple-electron emission 2. focusing with electrostatic lens 10 fsec 3. verify ultra-low emittance 4. verify ~700 attosec bunch GND 5. modulate energy

grid Electrostatic field emitter lens Accelerator tip cell

MCP

graduate student Anthony Serpry Concept of field-emission arrays: J.W. Lewellen, J. Noonan, “Field-emission cathode gating forPanel rf electron on Light guns”, Source Phys. Facilities, Rev. National ST AB Sc 8 ience033502 Foundation (2005) Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Development of the three key laser-driven components Group

source of free accelerator undulator particles section

develop MEMs based laser-driven accelerator structures Objective: 1. Dielectric optical MEMs structures 2. High acceleration gradients (~ 1 GeV/m) 3. Mono-energetic, maintenance of low emittance

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Proposed parameters for laser driven SASE–FEL Byer Group

Laser accelerator undulator Solid state ~ 1 GeV laser λ ~ 1 µm ~ 2 m

λ Input electron beam undulator ~ 1-2 GeV beam energy λu ~ 200 µm ~ 10 attosec pulse duration L ~ 20-40 cm 3 fsec u 10 attosec ~ 1 pC bunch charge B ~ ½ - 1 T pulse structure 0 ~ 0.05% energy spread

Field envelope growth Smallest ∂ ~  −iψ  E()z′,t = −χ  e j v  electrons per possible 2 ∑ ∆  beam size ∂t  j∈∆  unit volume

φb < 500 nm Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Development of the three key laser-driven components Group

source of free accelerator undulator particles section

Periodic Magnetic Undulator Field strength ~ 1 Tesla First Idea: Modulation Period ~ 0.1mm Length ~ 30cm

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Attosecond X-ray FEL Source – First Approach Group

1 10 500 12

450 λr E = 100 MeV 0 10 10 ε ≤ 400 σ ≤ ρE 10 Starting point 10 4π 400 E q = 1 fC /bunch 350 λ = 100 µm 8 u L -1 100 MeV LLRG> R 1-D FEL model 101 300300 Design parameters 70 Å λu ~ 28 µm 250 66 must satisfy these -2 conditions 0.110 200200 (mm) length ε ~10-3 µm-rad energy spread (keV) 4 150 L length (mm) G minimum FEL wavelength (nm) -3 0.0110 100100 energy spread (keV) 22 50

min,. wavelength FEL (nm) -4 10 0 0 -3 -2 -1 0 1 2 10 0.0110 0.110 101 1010 10 0 0.5 11 1.5 22 2.5 33 0 0.5 11 1.5 22 2.5 33 beam energy (GeV) electron beam size (microns) electron beam size (microns) beam energy (GeV) electron beam size (µm) electron beam size (µm)

5.5 -9 5 E = 100 MeV L ~ 1 cm L ~ 1 cm ε ~10 m-rad λ ~ 18 attosec 5 FODO G b q = 6250 e/bunch (1 fC) -7 4.5 o ~ 3 µm L ~ 30 cm q ~ 1 fC U ~ 10 J λuλu =~ 100 100 µm µm xy sat b b 44 λ De =~ 3 µ1m nm 3.5 r ~ 30 cm 3 Undulator 3 ~ 3 µm 2.5 ~ 1 cm design wave;engthwave;ength (nm) (nm) wavelength (nm) 22 1.5 11 0.5 50 60 70 80 90 100 110 120 130 140 150 60 80beam energy 100 (MeV) 120 140 beam energy (MeV)

frep ~ 1 MHz -7 Laser power ηacc ~ 1% 1% 1% of Ub = 10 J 7 required Pacc ~ 10 W laser power conversion U ~ 10 Photons η ~ 10 % wallplug efficiency efficiency laser ~ 1 nJ/pulse Pe ~ 100 W electrical power

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 59 Development of the three key laser-driven components Byer Group

KEY IDEA: Use fsec laser to Drive Dielectric Undulator

source of free accelerator undulator particles section

develop MEMs based laser-driven deflection structures Objective: 1. Dielectric optical MEMs structures 2. High gradients (~ 1 GeV/m) 3. Possibility for compact undulators

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer The structure geometry determines the force component Group

accelerator structure deflection structure

r r r r r r E⊥ + ()v × B ⊥ = 0 E⊥ + (v × B)⊥ ≠ 0 r r 1 1 F⊥ q ~ 5 Elaser → ~ 2 GeV/m E|| ~ 2 Elaser → ~ 4 GeV/m key idea extended phase-synchronicity between the EM field and the particle

T. Plettner, “Phase-synchronicity conditions from pulse-front tilted laser beams on one-dimensional Panel on Light Source Facilities,periodic National structures Science and Foundationproposed laser-driven Wednesday deflection”, 9 submittedJanuary 2008to Phys. Rev. Lawrence ST AB Livermore National Laboratory Byer The expected phase-synchronous force components Group

a) b) n = 1.58 0.6λp yˆ′ xˆ′ G⊥,x′ G||,y′

0.4λp particle λ trajectory p θ xˆ G⊥,z′ zˆ yˆ G⊥,total incoming wave zˆ′

c) d) 0.40.4 0.25

0.2 0.3 0.2 G||,y′ 0.15 G||,y′ 0.20.2 G G⊥,z′ 0.10.1 ⊥,z′ 0.1 0.05 G ′ 0.00 ⊥,x 0.00 G⊥,x′ -0.05 -0.1 -0.1-0.1 normalized gradient gradient gradient normalized normalized normalized -0.2-0.2 gradient gradient normalized normalized -0.15 -0.3 -0.2-0.2 TE polarization TM polarization -0.4-0.4 -0.25 −0π 50 1000 150 +200π −0π 50 1000 150 +200π Panel on Light Source Facilities, Nationaloptical Sc phaseience Foundation(φ) Wednesday 9 January 2008 optical Lawrence phase (φ )Livermore National Laboratory Byer A dielectric structure undulator Group

deflection pulse-front structure tilted laser sections beams

undulator period λu undulator period λu

• same loss factor as the laser accelerator: ~100 GV/m/pC • similar structure geometry Æ fabrication compatibility

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 1D model of Attosecond 120keV FEL Byer Group simulation parameters expecteda) temporal expected temporalb) 2.020 profile at 12 cm 6.060 profile at 15 cm τ U b = 2 GeV 1.818 = 5 attosec 5.050 ε b 1.616 −9 1.414 N =10 m - rad 4.040 1.212 Qb = 20 fC 1.010 3.030 γ 0.88 ∆γ = 0.1% powerpower (GW) (GW) powerpower (GW) (GW) 2.020 σ 0.66 r = 200 nm 0.44 1.010 β * = 4 cm 0.22 0 0 -6 -4 -2 0 2 4 6 -6 -4 -2 0 2 4 6 8 10 λ = 0.3 mm -6 -4 -2 0 2 4 6 -6 -4 -2 0 2 4 6 8 10 u time (attosec) time (attosec) K = 0.13 expected temporal pulse fluence vs. profilec) at 27 cm undulatord) length short pulse regime 8.080 6 7.070 10106

60 6.0 55 Lc ~ 21λr 1010 5.050 4 10104 4.040 σ b ~ 136λr 30 3 3.0 103 power (GW) (GW)power power 10 2.020 LG ~ LG0 (1+ N sλr 3σ b )

numbernumber of ofphotonsphotons 2 10102 1.010 −4 ρ eff = U FEL U beam ~ 5×10 1 σ L ~ 6 0 101 b c -10 -5 0 5 10 15 20 10 100 200 300 400 500 600 700 800 900 -10-50 5 101520 200 400 600 800 time (attosec) undulator period

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Experiments to be conducted at SLAC Group

Test of laser-deflection Structure

2 cm 1 mm

laser off electron (no deflection) beam 60 MeV

laser on

laser focusing triplet beam

ProveProve the the concept concept of of a a phase-synchronous phase-synchronous deflection deflection force force

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Measure Deflection of the Delectric Laser Driven Undulator Byer Near-future experiment at E163 Group

laser off laser on PI MAX camera vertical vertical dimension

Ce:YAG energy scintillator screen

discarded filtered electrons electron 45° pulse-front beam tilted laser beam 60 MeV electron beam

90 degree deflector spectrometer structure magnet 1 mm Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Experiments to be conducted at SLAC Group

Look for undulator radiation

K2   K 2   K2  N =πα J  − J   pulse-front tilted laser ph 2 2  1 2 2  0  2 2  beam ()1+ K 2   4()1+ K 2   4()1+ K 2 

mask or high- reflector electron beam λu = 1 mm

undulator deflection radiation structure Prove the concept sections 4 N ph ~ 3×10 ω λ ~ 40 nm K ∝ω λu pulse-front tilted laser r beam measure ∆θ =1 Nu λ ∆ = 2 r λu Nu

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Contents Byer Group

Historic Background

The TeV-Energy Physics Frontier

Laser Electron Accelerator Project – LEAP HEPL Experiments from 1997 – Nov 2004 E163 Experiments at SLAC Laser accelerator structures Inverse FEL for electron pulse compression

Coherent X-ray laser Generation Components of the X-ray laser Dielectric Accelerator and Undulator Structures FEL gain and efficiency

Future Challenges Table Top Synchrotron Source

“Don’t undertake a project unless it is manifestly important and nearly impossible.” Edwin Land – 1982

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory A first step towards a Laser Accelerator driven Byer Table Top Synchrotron X-ray Source Group

{Bending radius ~ 1m for 1GeV electron source}

Bending radius from a deflector structure 4

3.5 F⊥ q ~ 1.3 GV/m

3 γ mc2β 2 2.5 r = F⊥ 2

1.5 bending radius (cm)

0.5

0 0 5 10 15 20 25 30 35 40 45 50 energy (MeV)

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Summary Group

• injector Dielectric structure FEL • accelerator Laser-driven • undulator

1. photon energy of tens of keV properties 2. ~105 photons/pulse 3. 80 MHz Æ 1012 photons/sec

• laser-particle accelerators (LEAP/E163) initial work • field-emission injector • modeling of the undulator and FEL process

• dielectric structure accelerators future • test a laser-driven deflector • construct a low-energy pre-accelerator

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Long-term experiments Group

Inject higher density of optically bunched electrons into the structure ¾ search for small-signal gain ¾ verify predicted beam loading and wakefield effects

Test other materials for dielectric structures ¾ verify index of refraction and transparency window ¾ perform laser-damage threshold tests ¾ radiation damage tests

Integration of the components ¾ cascading of ~103 mm-long accelerator sections ¾ cascading of ~102 sub-mm long deflection sections ¾ beam transport: steering and periodic focusing ¾ beam diagnostics: BPMs, etc

Refinement of the idea ¾ undulator optimization: periodic focusing, tapering, etc. ¾ seeding, resonator configuration ¾ harmonic generation

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Group

Acknowledgements

1. R. Ischebeck, E. Colby, R. Siemann, C.M. Sears, S. Fan, and Z. Huang 2. P. Hommelhoff and M. Kasevich for guidance on field- emission tips 3. H. Injeyan and R. Rice for discussing possible applications of the proposed X-ray sources 4. The NLCTA personnel at SLAC for guidance on operating the test accelerator

This work is supported by 1. accelerator work: supported by DOE DE-FG06-97ER41276 2. light-source application: supported by Northrop Grumman

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Group

Relativistic electron laser-acceleration group

Chris Bob Bob Eric Chris McGuinness Siemann Byer Colby Sears

Low-energy electron laser acceleration group Mark Kasevich Patrick Lu, K-Xun Sun

Anthony Catherine Peter Serpry Kealhofer Hommelhoff

Rasmus Chris Ben Tomas Jim Ischebeck Barnes Cowan plettner Spencer

Bob Noble past collaborators Y.C. Huang Dieter Walz T.I. Smith H. Wiedemann Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Selected publications Group

1. Y.C. Huang, D. Zheng, W.M. Tulloch, R.L. Byer, “Proposed structure for a crossed-laser beam GeV per meter gradient vacuum electron linear accelerator”, Applied Physics Letters, 68, no. 6, p 753-755 (1996)

2. Y.C. Huang, T. Plettner, R.L. Byer, R.H. Pantell, R.L. Swent, T.I. Smith, J.E. Spencer, R.H. Siemann, H. Wiedemann, “The physics experiment for a laser-driven electron accelerator”, Nuclear Instruments & Methods in Physics Research A 407 p 316-321 (1998)

3. X. Eddie Lin, “Photonic band gap fiber accelerator”, Phys. Rev. ST Accel. Beams 4, 051301 (2001)

4. E. Colby, G. Lum, T. Plettner, J. Spencer, “Gamma Radiation Studies on Optical Materials”, IEEE Trans. Nucl. Sci. Vol. 49, No. 6, p. 2857-2867 (2002)

5. B. M. Cowan, “Two-dimensional photonic crystal accelerator structures”, Phys. Rev. ST Accel. Beams 6 101301 (2003)

6. R.H. Siemann, “Energy efficiency of laser driven, structure based accelerators”, Phys. Rev. ST AB. 7 061303 (2004)

7. T. Plettner, R. L. Byer, R. H. Siemann, “The impact of Einstein’s theory of special relativity on particle accelerators”, J. Phys. B: At. Mol. Opt. Phys. 38 S741–S752 (2005)

8. Y. C. Neil Na, R. H. Siemann, R.L. Byer, “Energy efficiency of an intracavity coupled, laser-driven linear accelerator pumped by an external laser”, Phys. Rev. ST. AB. 8, 031301 (2005)

9. T. Plettner, R.L. Byer, E. Colby, B. Cowan, C.M.S. Sears, J. E. Spencer, R.H. Siemann, “Visible-laser acceleration of relativistic electrons in a semi-infinite vacuum”, Phys. Rev. Lett. 95, 134801 (2005)

10. C.M.S. Sears, E. Colby, B. Cowan, J. E. Spencer, R.H. Siemann, T. Plettner, R.L. Byer, “High Harmonic Inverse Free Electron Laser Interaction at 800 nm”, Phys. Rev. Lett. 95, 194801 (2005)

11. T. Plettner, R.L. Byer, E. Colby, B. Cowan, C.M.S. Sears, J. E. Spencer, R.H. Siemann, “Proof-of-principle experiment for laser-driven acceleration of relativistic electrons in a semi-infinite vacuum”, Phys. Rev. ST Accel. Beams 8, 121301 (2005)

AARD subpanel Dec 21, 2005 Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 74 Byer

W. K. H. Panofsky, SLAC Beamline, 1997 Group The Livingston curve 1. near-exponential growth in the beam energy up until about 1990

2. LHC and future NLC/ILC lie below the exponential growth curve

3. Exponential curve important for new physics

RF based accelerator technology is nearing its practical high-energy limit

For future high energy collider facilities beyond the LHC and ILC it becomes increasingly appealing to invest in new Future Maximum gradient ~ 1000 MeV/m accelerator technologies

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Group

• BACK UP SLIDES

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Proposed parameters for laser driven SASE–FEL Byer Group

2 m ½m beam laser accelerator dump low energy high energy field emission tip

undulator oscillator ~200 µm laser amplifiers

cylindrical cylindrical vacuum ~50 µm lens lens channel laser beam ~ 40 cm

1 pC, top view 2 GeV, λu = 200 µm, Lu = 40 cm z rb ~ 200 nm electron λ/2 B ~ 1 T beam y x λ Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 28 9 x 10 x 10 6 14 Byer Photon field buildup Time profile of Group 12 1 pC, 5 SASE FEL pulses 2 GeV, λu = 200 µm, 10 4 3000 periods rb ~ 200 nm 8 B ~ 1 T 3 6 power (W)

2 Power (GW)

millions of photons 4

1 2

0 0 0 500 1000 1500 2000 2500 3000 0 10 20 30 40 50 60 70 80 90 100 time (attosec) 02040 60 undulator position (cm) -5 x 10 1 6x1066 photons 0 Loss of kinetic energy 6x10 photons -1 11 photon/electronphoton/electron -2 -3 1010 GWGW peakpeak powerpower -4 ~15 attosec FWHM -5 ~15 attosec FWHM -6 ~20 attosec timing jitter -7 ~20 attosec timing jitter -8 EEγγ~~ 190190 kevkev -9 0 500 1000 1500 2000 2500 3000 Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Laser damage and radiation damage studies Group

Radiation damage studies Laser damage threshold studies

borofloat, air, chamber undamaged sample 1000

100

damaged sample 10

1 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7

fluence (J/cm 2)

) 2.5 2

air damage threshold 2 vacuum material air vacuum

CaF2 2.212 2.260 1.5 borofloat 2.064 2.054 fused silica 2.027 1.795

sapphire 1.574 1.152 1 fluence (J/cm MgF2 1.455 1.455 800 nm HR 0.769 0.768 0.5 LiNbO3 0.504 0.194

0 CaF2 borofloat fused silica sapphire MgF2 HR coating LiNbO3

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Laser research Group

5 0

-5950 1000 1050 1100Original 1150 Pulse -10 Broadened Pulse 1 -15 Broadened Pulse 2 -20 Broadened Pulse 3 -25

Power (dBc) Power -30 -35 -40 -45 Wavelength (nm) Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory The SCA-FEL facility Byer Group

The SCA Accelerator provided a source of 30MeV electrons for LEAP

SCA beam parameters Beam Energy ~30 MeV amplified laser LEAP T ~2 psec electron Commercial, tabletop area Charge per bunch ~5 pC amplified sub-psec Energy spread ~20 keV mJ/pulse laser sources

λlaser 800 nm Elaser 1 mJ/pulse

superconducting FEL collimator accelerator structures wiggler slits kicker

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 81 Laser acceleration concept Byer Group

dielectric accelerating electron conceptual idea waveguide force bunch Pantell, 1979 laser in structure laser out

electron beam

dielectric laser beam z material

boundary d θ Ez ()z′ dz′ > 0 ∆UEdz=⋅θz ∫ vacuum channel ∫ θ 0 θ ψ ψ zˆ 2 2 2E sin  ()θ sin  E = − θ0 exp− d ×cos E z 2 ω2 3/ 2 2 2 t 1 x (1+ zˆ cos )  1+ zˆ cos  E θ 1x θ θ Magnitude Phase z θ E 3 3 2 U ()z = E z′ d (z′ ) 1z z zˆ cos ⋅ tan θ z = k ⋅ z ⋅cos − ⋅t + − 2⋅ tan −1()zˆ cos +φ ∫ t 2 2 2 0 z0 d ()1+ zˆ cos E2z

E2x Plane Wave Phase Math Gouy Phase E 2 †P. Sprangle, E. Esarey, J. Krall, A. Ting, Laser Acceleration of Electrons in Vacuum, Optics Comm. 124 (1996) 69

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 82 The LEAP experiment Byer (Laser Electron Accelerator Project) Group

laser The field-terminating boundary beam

0 Edzz ⋅>0 spectrometer ∫−∞ electron 1.0 beam Observed energy profiles 0.8 Laser ON Laser OFF 8 µm thick gold- 0.6 coated Kapton tape camera 0.4

0.2

stepper motors NormalizedNormalized chargecharge per per unit unit energyenergy optical phase of the laser -40 -20 0 20 40 0 −π -½π ½π Energy spread (keV)

decelerating phase broadening of max

U the initial +∆ energy spread max

U of the electron −∆

electron energy beam accelerating phase

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 83 “New” technology: the laser Byer Group

60 W/bar 50% now 78% electrical efficiency

high power solid state lasers high power fiber lasers damage threshold of dielectric materials

NUFERN ALABAMA LASER modelocked laser technology

Stuart, et. al,, Phys Rev. Lett. Vol 74, No 12 p. 2248 (1995) 10 GV/m fields for 100 fsec laser pulses

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Near-future experiment at E163 Group Laser-acceleration from a quartz-based mm-long accelerator microstructure

2 cm 1 mm

electron beam to the energy 60 MeV spectrometer

laser beam

focusing triplet fabricated by graduate student P.P. Lu a) b)

fabricated by graduate student C.M. Sears Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory The concept of a laser-driven particle deflection micro-structure Byer Group

accelerator structure deflection structure

r r r r r r E⊥ + ()v × B ⊥ = 0 E⊥ + (v × B)⊥ ≠ 0

r r 1 1 F⊥ q ~ 5 Elaser → ~ 2 GeV/m E|| ~ 2 Elaser → ~ 4 GeV/m key idea extended phase-synchronicity between the EM field and the particle

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Byer Near-future experiment at E163 Group

laser off laser on PI MAX camera vertical vertical dimension

Ce:YAG energy scintillator screen

discarded filtered electrons electron 45° pulse-front beam tilted laser beam 60 MeV electron beam

deflection pulse-front structure tilted laser sections beams

undulator period λu undulator period λu

• same loss factor as the laser accelerator: ~100 GV/m/pC • similar structure geometry Æ fabrication compatibility

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Calculated 120 KEV X-ray FEL Performance Byer Group simulation parameters expected temporal expected temporal U b = 2 GeV a) b) τ 2.020 profile at 12 cm 6.060 profile at 15 cm b = 5 attosec 1.818 ε 5.050 =10−9 m - rad 1.616 N 1.414 4.040 12 Qb = 20 fC 1.2 γ ∆γ = 0.1% 1.010 3.030 0.88 powerpower (GW) (GW)

powerpower (GW) (GW) 20 σ 6 2.0 r = 200 nm 0.6 0.44 β * 1.010 = 4 cm 0.22

0 0 λu = 0.3 mm -6-6 -4-4 -2-2 00 22 44 66 -6-6 -4-4 -2-2 00 22 44 66 88 1010 K = 0.13 time (attosec) time (attosec) expected temporal pulse fluence vs. profilec) at 27 cm undulatord) length short pulse regime 8.080 6 7.070 10106

60 6.0 55 Lc ~ 21λr 1010 5.050 4 10104 4.040 σ b ~ 136λr 30 3 3.0 103 power (GW) (GW)power power 10 2.020 LG ~ LG0 (1+ N sλr 3σ b )

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Linear accelerators - accelerating relativistic Byer electrons Group v/c electron relative velocity velocity relative electron Superconducting Accelerator 100 keV 1 MeV 100 MeV 10 GeV 1 TeV electron kinetic energy

0 eV 100 keV ~ 2 MeV ∆U ≤ 50 MeV/m ∆x

electron DC potential RF modulator pre-accelerator accelerator structures source (buncher) β →1 β = 0 β ~ 1 2 Schematic of a linear accelerator

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory Dream: Table Top Attosecond X-ray FEL Source Byer Group

1° of optical phase at 2 µm Æ 20 attosec

attosec light sources

N N N N N N N N N N N N S S S S low energy 100 MeV Prof. Byer’s dream…

e-beam 110 V S S S S S S S S S S S S N N N N

20 asec

N N N N N N N N N N N High strength Nd:Fe N

micromagnets S S S S

S S S S S S S S S S S

N S N N N

Take advantage of ultra-low 1m emittance laser-accelerator e- beam and new magnetic materials The wizard of optics Preliminary model studies • 1st initial feasibility study with the 1D FEL model Table Top attosec x-ray • Attosec bunching of 1fC helps enhance the gain source with medical and • “low” 1 MHz rep. rate Æ low avg. power • Further more refined studies under way chemistry applications • It deserves a closer look

Panel on Light Source Facilities, National Science Foundation Wednesday 9 January 2008 Lawrence Livermore National Laboratory 91