LOASIS Program:All-optical accelerators

Wim Leemans

LOASIS Program

Accelerator and Fusion Research Division

Website: http://loasis.lbl.gov/

Acknowledgment

Staff/students of l’OASIS team

E. Esarey, C.Filip*, G. Fubiani, C. Geddes, E. Michel*, P. Michel, B. Nagler, K. Nakamura, C. Schroeder, B. Shadwick, C. Toth, J. van Tilborg,

D. Syversrud, M. Dickinson, N. Ybarrolazza, J. Wallig

*University of Nevada, Reno

Primary CollaboratorsS. Hooker, A. Gonsalves- Oxford University

D. Jaroszynski-Strathclyde, AlphaXT. Cowan, N. Le Galloudec, H. Ruhl, A. Kemp- UNR

J. Cary, D. Bruhwiler, D. Dimitrov-U Colorado Boulder, TechX-Corp

DOE -HEP Advanced Accelerator Technology

17 3 11112

Challenges

• Building a high energy collider:– Single stage ?

• 200 m long plasma, BIG laser (200 PW for 1 TeV?)• Will beam remain stable ? Will emittance be OK?

– Multi-stage ?• How to stage ? Build 10 GeV module, how to couple beams in

and out ?• How to manage 100 - 1000, 0.1-1 PW systems? 100 Hz?

• Radiation source– Coherent emission: THz– X-FEL: is beam quality good enough ?

• Energy spread• Emittance• Maintaining peak current: bunch propagation

• Particle source:– fs, MeV electron bunches, pC, 10 micron spot, E/E <<

Experimental activities/focus

10 TW system

–High density plasma channels• “Low” phase velocity wakes• Dark current free structure• 100 MeV-class beams

–Injection physics–THz and X-rays

100 TW system

–Low density plasma channels• “High” phase velocity wakes

–1 GeV module–Capillary discharge:

• Collab. With Oxford (UK)

CCD &Spectrometer

2 probe

InterferometerHeater beam

e-

H, He gas jetMain beam

IgnitorBeam

Next step: 1 GeV compact module100 TW laser + plasma channel

Plasma injector

Plasma channel

e- beam

< 3mm < 10 cm

1.2 GeVLaser

100 TW, 40 fs10 Hz

A. Reitsma et al., PR-STAB 2001

€

Wd[GeV] ~ I[W/cm2] n[cm-3]

2-7 cm long

+

•Collaboration with Oxford University and Alpha-X

Bigger laser

LWFA’s brightness offers unique opportunities

Data: Nature 2004

Brightness = (beam power)/(phase space volume)

Bri

gh

tnes

s

Particle energy [GeV]

Brightness vs.

103

105

107

109

1011

1013

1015

0.01 0.1 1 10 100

Present LWFA

Linacs

Future LWFA

SLAC FFTB

10 GeV LWFA

1 GeV LWFA

LOA

LBNL

RAL

Photocathode

Thermionic

Single drive beam experiments have been conducted for laser accelerator produced THz and X-rays

THz emitted at vacuum-plasma boundary

Short bunches result in coherent emission

Radiation source+bunch diagnostic

Radiation characterized via:

Michelson interferometer

Semiconductor switching

Electro-optic effect in ZnTe

Set-up for E-O effect

THz TR 50fs ProbeBeam (800nm)

Polarizer

Analyzer

ZnTe

Diode

Chamber

/4

Shot-to-shot stability in charge and bunch duration enables scanning E-O sampling technique

Time Jitter and Stability

Jittere-beam &probe beammust be << 30 fs

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

-400 -200 0 200 400

Diode [V]

Time [fs]

Charge Stability over Time < 5 % rms

-0.5

0

0.5

1

1.5

2

2.5

3

11.8 12 12.2 12.4 12.6 12.8 13 13.2

Charge [nC]

Decimal Time [hrs]

Jet On

Jet Off

• Spectrum consistent with 50 fs bunch

• THz depends primarily on charge,

bunch duration

• Shot-to-shot stability of those quantities

J. Van Tilborg et al., in preparation

u

x=u/22

Betatron (synchrotron) radiation:

Ultra-short x-ray generation from laser accelerated e-beams

parameters:

Q=03 nC

E=100 MeV

rb=3 m

ne=2 x1019 cm-3

Lchannel=1 mm

E. Esarey et al., PRE 2002A. Rousse et al., PRL 2004

• Betatron emission:• “Spontaneously” emitted• Detector testing• First phase of x-ray diagnostic

• Collaborations:• LLNL• UNR

LOASIS Program at LBNL

• Tools: multi-beam, multi-arm laser

• Radiation shielded experimental areas+remote control room

• Two target areas: – 10 TW (+10 TW), 3 independent vacuum compressors

– 100 TW arm

• Physics:– Precision frontier: all-optical injection enabled by discovery of dark current free structure

– High energy acceleration:

• Channel guided laser wakefield: 100 MeV (Nature 2004)

• Capillary discharge + injection: towards 1 GeV

– Radiation sources: taking advantage of peak brightness

• Intense THz via coherent transition radiation (PRL 2003, PRE 2004, PRL

2005(submitted))

• Incoherent x-rays: betatron, Thomson scattering-gamma rays

• Coherent x-rays: XFEL

LOASIS Program FY05: Staff + visitors and students