Laser-Plasma Acceleration in Sweden

ElectronsProtons

X-rays

Claes-Göran WahlströmDepartment of Physics, Lund University

and Lund Laser Centre

Lund - an old city with a large

university

Lund - A city with a strong accelerator future

LWFA

3.5 GeV e-

2.5 GeV p+2020

Ion source

2.5 GeV ProtonAccelerator

Klystrons

SpallationTarget station

Neutron Instruments

European Spallation Source - ESSGoal: Neutrons in Lund before 2020

Investment: 1.5 B€ / ~10yOperations: 10 M€ / y

-390 m length-2.9 ms pulses-2.5 GeV proton energy-14 Hz-5 MW average beam power

  

ESS 2.5 GeV proton LINAC

Ongoing international R&D

Mats Lindroos – Project leader

Electron source

3.5 GeV Linear accelerator (ca 250 m)

MAX IV with its 3.5 GeV LINAC

Short Pulse Facility

FEL expansion

3 GHz normal conducting100 Hz rep rateRF photo cathode gun2 bunch compressors

3 Operation modes: Ring injection / SPF /FELEmittance (norm): 0.4-1 mm mRad (FEL/SPF-mode) Charge: 20-100 pC (FEL/SPF-mode)Bunch length: 100 fs

3 GeV Ring (528 m circ.)

• Established at Lund University in 1995

Atomic Physics Combustion PhysicsLaboratory AstrophysicsChemical PhysicsLU Medical Laser CentreLaser research at MAX-lab

• ~110 Scientists, incl. 14 Professors, 65 PhD. Students

• European Large Scale Infrastructure since 1996

Lund High-Power Laser Facility

LASERLAB-EUROPE The Integrated Initiative of European Laser Laboratories

Lund Laser Centre – a partner in Laserlab-Europe

The LLC provides Access to External Users

The Lund Multi-Terawatt Laser10 Hz, 800 nm, 35 fs, 40 TW

The Ultra-High Intensity Laser Physics Group

Matthias Burza Guillaume Genoud Franck Wojda

Anders Persson

Kristoffer Svensson

Olle LundhLovisa Senje Martin Hansson         C-G W

~6% of LLC

Stuart Mangles, A. Thomas, S. Kneip, Z. Najmudin, K. Krushelnick, N. Dover, M. Bloom, M. Kaluza, C. Kamperidis et al..Plasma Physics Group Imperial College, London, UK

Brigitte Cros, K. Cassou, F. Wojda, Jinchuan JU, et al. Laboratoire de Physique des Gaz et des Plasmas (LPGP), Université Paris Sud 11, Orsay, France

With the support of MaxLas, EuroLEAP and Laserlab Europe

Key Collaborators for Electron Acceleration

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• 35 fs, 680 mJ Laser pulses• f/10 focusing

LWFA with IC London 2005 -

LWFA of Monoenergetic Electron Beams in the First Plasma Wave Period Mangles et al. PRL 96, 215001 (2006).

Electron Beam Profile

• Electron Beam Profile (E > 7 MeV) elliptical

• Axis of ellipse along direction of laser polarization 

• Electron motion in E-field of the laser increases beam divergence in direction of polarization

– Electrons and laser overlap spatially 

Laser polarization

Electron beam profile

Beam

 profile tilt  

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Laser polarization º

• r = 107• r = 106

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Electron beam stability - contrast ratioPlasma Physics and Controlled Fusion 48, B83 (2006). 

Effect of Coma on the electron beam

• flat wavefront:– e-spectrum well collimated 

and no variation of beam position with energy

• 0.175 λ coma:– Beam divergence is increased– e-beam exhibits variation of 

beam position with energy, amplitude ~ 20 mrad

Profi

leElectron sp

ectrum

Flat wavefront 0.175 λ coma

Effect of Coma on the X-ray spectrum

• increasing the amplitude of coma aberration clearly increases the critical energy of the X-ray spectrum

→ increase oscillation amplitude from rβ = 1 ± 0.4 μm to 3 ± 1 μm

2332

ck

Er c

Mangles et al., Applied Physics Letters 95, 181106 (2009).

Effect of Spherical Aberration on theWavebreaking Threshold

Submitted (2011)

• Material: Glass• Length: 10 to 100 mm• Inner diam: 100-150 μm• Filled with H2

• Excellent matched guiding over several cm possible• Technical challenge: very sensitive to laser pointing and spot quality

L

Hollow Dielectric Waveguide CapillariesWith LPGP Orsay, Brigitte Cros et al. 

F. Wojda et al., Phys. Rev. E 80, 066403 (2009).

Implementing Adaptive Optics in the Compressed Beam

Before After

Labview FPGA

Active Pointing StabilizationG. Genoud et al. Rev. Sci. Instr. 82, 033102   (2011)

t

dippiezo dtdeKdeKteKtV

0)()()(

Piezo mirror 2D Photo-sensitivedetector

Target

FIR digital filter

Reference beam

Fast shutter

laser pulse,40 fs, 700 mJ

CCD camera and objective

X-ray sensitive CCD camera

Metalic filters

Lanex screen+aluminium shield

Magnet

Deformable mirror

f/9 off-axis parabolic mirror

Capillary, multimode

Electrons and X-rays from CapillariesG. Genoud et al. Submitted 2011

1. Estimation of the source position G. Genoud et al. Submitted (2011)

→ X-ray emission stops after ~3 mm behind the laser focus

Laser focus End of X-ray source?

Betatron X-rays from Capillaries

→ upper limit for the transverse source size ~7 µm

a

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Line-out

l

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ba

Detector

2. Estimation of the source size

Betatron x-rays from Capillaries

Electron Acceleration at the Lund Laser Centre

•10 Hz Multi-TW laser•Gas jets

•Quasi-monoenergetic electrons•Stability studies•Beam quality studies•Wavebreaking studies•Betatron X-rays

•Gas-filled dielectric capillaries•Linear plasma waves over long distance•Electron acceleration inside capillaries•Betaton X-rays emission

Plans, facilities... Tomorrow

The MAX-lab test-FEL facility

Modulatorundulator

Chicane

Radiatorundulator Half-chicane

Dog-leg Linac 1Linac 2

RecirculatorGun

Dump

Gun laser

Seed laser

Mono-chromator

Ti:SapphireSeed laser

Ti:SapphireGun laser

Optical fibre