dino jaroszynski university of strathclydew3fusion.ph.utexas.edu/ifs/aac2012/files/plenaries/aac...

AAC June 2012 SCAPA [email protected]

Scottish Universities Physics Alliance

The development of laser-driven plasma accelerators:

progress and outlook

Dino Jaroszynski University of Strathclyde


• Accelerators and light sources

• Acceleration in plasma

• Narrow energy spread and low emittance beams

• Femtosecond duration bunches

• Improvements of stability and dark current

• FEL, betatron and undulator radiation

• Radiation imaging

• New projects

• Outlook

Outline of talk


CERN – LHC 27 km circumference

SLAC

50 GeV in 3.3 km

20 MV/m

7 TeV in 27 km

7 MV/m

Large accelerators depend on superconducting RF cavities and magnets


Synchrotrons light sources and free-electron lasers: tools for scientists

Synchrotrons and FELs – huge size

and cost is determined by accelerator

technology

Diamond

undulator

synchrotron

DESY undulator


Livingston plot

New ideas

lead to new

technologies

Acceleration

gradient

currently limits

maximum

energy

Laser

wakefield

accelerators?

(from tesla.desy.de)

http://tesla.desy.de/~rasmus/media/Accelerator


Plasma media: capillary, gas jet and plasma cells (Strathclyde)

2 mm

Gas jet

1 J, 40 fs

= 300 MeV

200

consecutive

Images

(Strathclyde)

4 cm

Gas Cell

10 J, 50 fs

= 850 MeV

(at RAL)

4 cm

Plasma capillary

10 J, 50 fs

~ 1 GeV (at RAL)


Strathclyde Plasma waveguide medium

4 cm long

preformed

plasma

waveguide

n = 1018 cm-3

Originally developed by

Simon Hooker’s group D. Spence & S. M. Hooker. Physical Review

E 63015401 (2001).

Strathclyde laser micromachining method: Jaroszynski et al., Philosophical Transactions of the Royal Society (2006)

Wiggins et al,, Review of Scientific Instruments (2011)


Particles accelerated by electrostatic fields of plasma waves

[V/cm]E e n

Accelerators:

Surf a 10’s cm long

microwave –

conventional

technology

Surf a 10’s mm long

plasma wave –

laser-plasma

technology 2

max

2

3

ga

0g

p

Tajima and

Dawson

1979 Accelerating gradients up

to 1 TV/m


Bubble structure – relativistic regime

laser

self-injected

electron bunch

undergoing

betatron

oscillations

ion bubble

First experiments

on controlled

acceleration:

2004

ALPHA-X (UK)

LBNL (US)

LOA (France)

0

2

paR

ion bubble radius


Theory: Influence of non-ideal laser and plasma parameters on LWFAs

Lasers with higher order modes*

less energy

into

accelerated

electrons

QuickPIC

laser energy

spreads sideways

Non-ideal plasma density profiles*

d

non uniformity

amplitude

density non-

uniformity:

may lower

energy gain

*J. Vieira et al., Plasma Phys. Control. Fusion 54, 055010 (2012).

QuickPIC


Energy scaling with density: bubble regime – experimental data

2

0

max

2

3

g a

1E16 1E17 1E18 1E19 1E2010

6

107

108

109

1010

1011

En

erg

y [

eV

]

Density [cm-3]

a0: 2 → 10

0g

p

Progress!

Experimental data from the community since 2006


ALPHA-X: Advanced Laser Plasma High-energy Accelerators towards X-rays – Template for SCAPA

Compact R&D facility to develop and apply

femtosecond duration particle, synchrotron,

free-electron laser and gamma ray sources

70 75 80 85 90 95 1000

250

500

750

1000

No

. e

lec

tro

ns

/ M

eV

[a

.u.]

Electron energy [MeV]

(b)

(a)

electron beam spectrum

phase contrast

imaging

with 50 keV

photons

beam emittance: <1 p mm mrad

CTR: electron

bunch duration:

1-3 fs 0.7%

Brilliant particle source: 10 MeV → GeV, kA peak current, fs duration

FEL 1J 30 fs

capillary &

0 5 10 15

0.0

0.1

0.2

0.3

Measured TR signal

1 fs

1.5 fs

2 fs

2.5 fs

3 fs

4 fs

TR

(J/m

)

Wavelength (mm)

= 2.8 nm – 1 mm

(<1GeV beam)

ALPHA-X

@ Strathclyde

30 TW


Narrow energy spread low emittance beams

100 110 120 130 140 150

8000

10000

12000

14000

16000

18000

Ch

arg

e/u

nit e

nerg

y [

a.u

.]

Energy [MeV]

0.75%

63 MeV 170 MeV

Maximum energy obtained in

2 mm = 360 MeV

Absolute energy

spread < 600 keV

Strathclyde


-0.75 -0.50 -0.25 0.00 0.25 0.50 0.75

-3

-2

-1

0

1

2

3

4

0 5000 10000 15000

x' [m

rad

]

x[mm]

arb. counts

• divergence 1 – 2 mrad for this run

with 125 MeV electrons

• average N = (2.2 0.7)p mm mrad

• best N = (1.0 0.1)p mm mrad

• Elliptical beam: N, X > N, Y

• Upper limit because of resolution

• Second generation mask with hole ~ 25 mm and improved detection system

0 1 2 30

5

10

Count

nx

[p mm mrad]

(a)

0 1 2 30

5

10

Count

ny

[p mm mrad]

(b)

Experimental Results – emittance

See Brunetti et al., PRL (2010) and Wed. WG 5


-6 -4 -2 0 2 40

5

10

15

20

cou

nts

horizontal position (mrad)

x = 1.4 mrad

(a)

-6 -4 -2 0 2 40

5

10

15

20

cou

nts

vertical position (mrad)

(b)

y = 1.3 mrad

Electron

beam

recorded on

YAG screen

High

resolution

Electron beam pointing deviation is less

than one spot size

Electron Beam- Pointing Stability at Strathclyde

no PMQs PMQs in


Recent electron bunch measurements – CTR from foils

1.4 – 1.8 fs CTR measurements at source

Lundh et al., Nature Physics (2011)

32 fs CTR measurements using EO

Cross-correlator

Debus et al., Phys. Rev. Lett. (2010)

Earlier measurements by

Leemans et al., PRL 2003

Tilborg et al., Optics Letter

2008, PRL 2006

Glinec et al. (PRL 2007) &

Lin et al., (PRL 2012)

measured visible CTR


Improved stability and tunability: Shock-front injection

5 µm transition

ATLAS

28 fs

550 –

800 mJ

8 fs, 70 mJ pulses

MeV

See talk by Laszlo Veisz


Scottish Universities Physics Alliance


Study of self-injection threshold and simple model to predict self-injection threshold

• Shows how self-focusing and pulse

compression are needed to explain

the threshold density for self-

injection

• Developed a simple model for

predicting threshold density based

on experimental parameters:

• Simple model in good agreement

with Imperial College and other

reported experiments over 3 orders

of magnitude in laser pulse energy

SPD Mangles et al PRSTAB 2012


Background-free, tunable, self-injected, LWFA electron beams

Reduced energy spread

P= 42 TW

S. Banerjee et al., Phys. Plasmas 19, 056703

(2012).

1.2

0.48

ne (1019

cm-3)

Tunable

(a) P = 34 TW, ne0 = 7.8×1018 cm-3

(b) P = 42 TW, ne0 = 6×1018 cm-3

(c) P = 58 TW, ne0 = 5.3×1018 cm-3 • Kalmykov et al., Plasma Phys.

Control. Fusion 53(1), 014006 (2011) & talk in WG1, Thurs.

• Kalmykov et al., New J. Phys. 14 (2012) 033025 & talk in WG1, Wed.


Beams generated in 3 regimes up

Relativistic self-focusing in a plasma channel

• Electron beams with energies up to 900 MeV

using 3.2 J, 55 fs pulses from Astra-Gemini

• Electron beams generated on 100% of 22

shots

• Low beam divergence 3.5 ± 1 mrad

• Electrons beams generated in self-guided,

plasma channel, and hybrid guiding regimes

• GRENOUILLE measurements show first

observation of laser pulse compression in

plasma channel

0.4 1 4

data

Emax [1]

Ldeph = Lcap

1000

800

600

400

200

0

plasma channel zone

plasma cannel and rel. focusing zone

self-guiding zone

max. el

ectr

on

en

ergy /

MeV

Raw electron spectra (22 consecutive shots)

plasma density / 1018 cm-3

Laser pulse duration vs. plasma density


f/40

1.1 T

dipole

magnet

Image plate

for < 0.5 GeV e-

Image plate

for GeV e- Beam

deflector

Beam

dump

e-

Energy (GeV)

2GeV 1GeV

Div

erg

en

ce

(mra

d.)

ne = 3.3 x 1017 cm-3

For details see:

X. Wang, WG1 Tuesday 10:30am talk

N. Fazel, Tuesday pm student poster slide courtesy Mike Downer, U. Texas-Austin

120 - 150 J

150 fs

7 cm

uniform

gas cell

99.99% high

purity He

QTOT = 1.8 nC

laser

polarization energy

calibration

fiducials

• sub-mrad beam

divergence

• negligible < 500

MeV dark current

• Self-injection

down to 1017 cm-3

Electrons accelerated beyond 2 GeV at the Texas Petawatt Laser

See LLNL results @ 1.3 GeV


Dual screen electron spectrometer allows measurement of beams > 1 GeV with Astra Gemini

1.3

• dual screen spectrometer allows

accurate energy measurement with fully

open magnet, providing large aperture

for betatron x-ray measurements

• 1.3 GeV electrons from 15 mm gas jets

in self-injecting, self-guiding regime

• betatron oscillations produce bright

hard x-rays peaked at ~ 30 keV

1.34 GeV

1.28 GeV

1.16

1.09


High Energy Electron Spectra

300 400 500 600

0

50

100

150

200

charg

e d

ensity [a.u

.]

Energy [MeV]

300 400 500

-50

0

50

100

150

200

Charg

e d

ensity [a.u

.]

Energy [MeV]

2.8%

600 800 1000-20

0

20

40

60

Charg

e d

ensity [a.u

.]

Energy [MeV]

3.9%

Strathclyde/SUPA/IST/RAL

GEMINI: Measurements

limited by spectrometer

resolution – maximum

energy measured 850

MeV


Bernhard Hidding1,2J.B.Rosenzweig, Y. Xi, G. Andonian, S. Barber, O. Williams2, F. Kleeschulte, G. Pretzler1, D. Bruhwiler3, K. Lotov4, M. Litos, M. Hogan5 P. Muggli6

Trojan Horse Plasma Photocathode Wakefield Acceleration

Idea: Use laser-plasma-produced electron bunches as plasma wave drivers in low-ionization threshold gases (e.g., alkali metal vapors). Advantages: no dephasing, strongly reduced diffraction (emittance) issues. Electron bunches from laser-plasma-accelerators could be especially well suited to drive plasma waves due to their compactness (see Hidding et al., PRL 104, 195002, 2010) Furthermore, a synchronized low-energy laser a0 0.015 can be used to release electrons of higher-ionization threshold species such as helium at arbitrary position within the blowout. This results in ultrahigh beam quality beams. Such a beam brightness transformer is ideal for light source applications such as FEL, Thomson scattering etc. (see Hidding et al., PRL 108, 035001, 2012, patent 2011, and talks in WG 4 on Tuesday)

Proof of concept experiments w/ laser-plasma-accelerators and at FACET planned: E 210: Trojan Horse Plasma Wakefield Acceleration, 2013 @FACET

Emittance and brightness of generated beams:


• Wiggler motion – electron deflection angle q ~(px/pz) is much larger than the angular

spread of the radiation j(1/γ)

• Only when k & p point in the same direction do we get a radiation contribution.

• Spectrum rich in harmonics – peaking at

• Radiation rate therefore only emission at dephasing length

1ua

deflection angle – au /

j=1/

33

8

ucrit

ah

2W dL

Synchrotron radiation from an ion channel wiggler: betatron radiation


Presence of laser in bubble: resonant motion


Resonant betatron motion

2 /( )Lyy y y F m / ( / )LyF e dA dt y A y

22

0 '2121'~gz

Cipiccia et al.,

Nature

Physics, 2011


Spectra:

Ec = 50 - 60 keV

Electron energy: 63070 MeV

ne= 2 x1018cm-1 r = 3 mm &

a ≈ 20

Ec = 150 keV

r = 7 mm

a = 50

Ec = 450 keV

r = 20 mm

a = 150

108 photons between .1 and 7 MeV

Brilliance 1023 photons/(s mrad2 mm2 0.1%bandwidth)

Betatron Radiation X-ray Spectra Measurements

Cipiccia et al., Nature

Physics, 2011


Ar

He magnet gap

10 mrad

I II

III IV

(a)

(b)

(c)

He Ar

50pC 500pC

7 mrad < 1 mrad

He

(a) (b)

(c)

Ar

5 (MeV) 10 15 20

(d)

Betatron radiation enhancement (>2.8keV, 10mrad, 2x10^8 phs, >1021 phs/s/../0.1%BW)

Using Ar clusters an electron beam with

large charge will be accelerated which

enhances the betatron radiation.

Electrons Betatron x-ray

Betatron radiation using 3TW laser + clusters

L.M. Chen et al.

IoP-CAS, Beijing


Betatron radiation to measure source size and emittance

source size of synchrotron radiation: rsyn = (1.8

0.3) µm

electron bunch radius rbunch = (1.6 0.3) µm

estimated peak brightness: 51021

photons/(smmmrad20.1%bandwidth)

see talk by M.C. Kaluza, WG 1+5 on Thursday

10:30 a.m. M. Schnell et al.: PRL 108, 075001 (2012).

• e- spectrometer - beam energy & divergence

• betatron radiation - beam source size

• combined to obtain emittance on a single shot

• emittance minimised in the matched regime


Divergence and source size

r = 7 mm source size

• divergence ≈

14 mrad

Betatron Radiation: phase contrast imaging at Strathclyde

Cipiccia et al.,

Nature Physics, 2011

Also see

Karsch’s talk


Recent VUV radiation undulator measurements

Strathclyde

undulator

radiation as an

electron energy

spectrometer:

Undulator:

100 period

1.5 cm

wavelength

Matched

transport system

Electron

spectrometer

after undulator:

simple low

resolution dipole

magnet

Also VUV

measurements by

Grüner’s group


Synchrotron, betatron and FEL radiation peak brilliance

ALPHA-X ideal 1GeV bunch

FEL: Brilliance 5 – 7

orders of magnitude larger

u 1. cm

n = 1 p mm mrad

te = 1-10 fs

Q = 1 – 20 pC

I = 1-25 kA

d < 1%

I(k) ~ I0(k)(N+N(N-1)f(k)) FEL = spontaneous

emission x 107

betatron source


Outlook

2

0

max

2

3

g a

1E16 1E17 1E18 1E19 1E2010

6

107

108

109

1010

1011

En

erg

y [

eV

]

Density [cm-3]

a0: 2 → 10

0g

p

Need a combination of bubble regime (Need to be above

critical power for relativistic self-focussing) and linear regime

to get to very high energies


International projects

• FACET – electron beam driven plasma wakefield accelerator:

100 GeV stage

• BELLA – laser driven plasma wakefield accelerator: 10 GeV

stage

• IZEST – Laser-driven plasma wakefield accelerator: 100 GeV

stage on PETAL Laser at LMJ

• EuroNNAC – Proton beam driven plasma wakefield accelerator

at CERN: 1-10 GeV Proof of Concept

• Fermilab – proton driven PWFA


Laser Plasma Accelerator

using conventional accelerator paradigm

Large-scale plasma-based acceleration

(Wim Leemans)

Laser: Ti:sapphire

40 J, 30 fs, 1 Hz

Parameter

Plasma density np 1017 cm-3

a0 1.4

Plasma wavelength p 108 mm

Pulse duration tL 57 fs

Spot radius rL 90 mm

Laser power P 563 TW

P/Pc 1.8


Facility for Accelerator Science and Experimental Test Beams – uses first

2km of the SLAC linac

Parameters

Energy 23 GeV

Charge 3 nC

Sigma z 14 mm

Sigma r 10 mm

Peak Current 22 kA

Species e- & e+

Ez = 37GV/m

Gain =15 GeV

DE/E =3%

Drive bunch:

σz = 30 μm

N = 3x1010 e-

Witness bunch:

σz = 10 μm

n =1x1010 e-

σr0 = 3 μm

Δz = 115 μm

(~400 fs)

ne=1017cm-3

Acceleration physics identical for PWFA and LWFA


EuroNNAc: PROTON-DRIVEN PWFA @ CERN

Proton beam SPS

Energy E0 450 GeV

Np 10.5 x 1010

DE/E0 0.03 %

z 12 cm

n 3.6 mm-mrad

r 200 mm

5 m

TT61 West ~600m tunnel + experimental area

Plasma

Length Lp 5 -10 m

ne 7x1014 cm-3

p 1.3 mm

fpe 240 GHz

~ GeV gain of externally injected e- over

5 - 10 m of plasma in self-modulated p+

driven PWFA


IZEST 100GeV @ LMJ Bordeaux Laser-Plasma Accelerator Experiment

Energy > 3 kJ

• Wavelength > 1053 nm

• Pulse duration between 0.5 and 10 ps

• Intensity on target > 1020 W/cm²

• Intensity contrast (short pulse): 10-7 at -7 ps

• Energy contrast (long pulse): 10-3

Design

guideline

1. self-injected

electron beam

from the injector

2. Quasi-linear

wakefield in the

accelerator

Find the optimum plasma density

Drive laser pulse

500 fs, 3.5 kJ max.

Acceleration length < 30 m

Gain

E~100GeV

Charge

Q~100pC

Quality

DE/E~1%

Emittance:

n~ 1p mm-mrad

Stability

100% reproducible

Mourou, Tajima et al.

(International Zetawatt Exawatt Science Technology)


Scottish Centre for the Application of Plasma Based Accelerators

Strathclyde: 2 Chairs (searching now*),

2 PDRAs, Technicians

Glasgow: 1 Reader

USW: 2 Readers/Lectures

Edinburgh SUPA Fellow

SCAPA: infrastructure + staff + beam

lines

* contact: [email protected]

1200 m2 laboratory space: 200-300 TW

laser and 7+ “beam lines” - particles

and coherent and incoherent radiation

sources for applications: nuclear

physics, health sciences, plasma

physics etc. Also part of Strathclyde

Technology and Innovation Centre (TIC)

Bunker B Bunker C

Bunker A

Control Area

10 m

Shielded area of laboratory


FIN

Thank you

dino jaroszynski university of strathclydew3fusion.ph.utexas.edu/ifs/aac2012/files/plenaries/aac...

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