Les Accélérateurs Laser Plasma

Victor Malka

Laboratoire d’Optique Appliquée

ENSTA ParisTech – Ecole Polytechnique – CNRS

PALAISEAU, France

[email protected]

Accelerators : One century of exploration of the infinitively small

Quarks

10

10

10

10

10

10

1880

1900

1920

1940

1960

1980

2000

2020

Year

Explored

wa

veleng

th

values

(m)

Cathodic tube

J. Thomson

1931 E. Lawrence, first

Cyclotron @ 80 keV

Univ. of Berkeley

380 MeV Cyclotron

Berkeley,

Bevatron

50 GeV

Synchrotron PS

28 GeV CERN

SLAC

50 GeV

LEP 90 GeV

CERN

Tevatron

FermiLab

LHC

3.5 TeV

CERN

Atom

Nucleus

Industrial Market for Accelerators

Application

(2007) approx.

Total systems

System

sold/yr

Sales/yr

(M$)

price (M$)

System

Cancer Therapy

9100

500

1800

2.0 - 5.0

Ion Implantation

9500

500

1400

1.5 - 2.5

Electron cutting and welding

4500

100

150

0.5 - 2.5

Electron beam and X rays irradiators

2000

75

130

0.2 - 8.0

Radio-isotope production (incl. PET)

550

50

70

1.0 - 30

Non destructive testing (incl. Security)

650

100

70

0.3 - 2.0

Ion beam analysis (incl. AMS)

200

25

30

0.4 - 1.5

Neutron generators (incl. sealed tubes)

1000

50

30

0.1 - 3.0

Total

27500

1400

3680

Total accelerators sales increasing more than 10% per year

The development of state of the art accelerators for HEP has lead to :

research in other field of science (light source, spallation neutron sources…)

industrial accelerators (cancer therapy, ion implant., electron cutting&welding...)

How to excite relativistic plasma waves ?

electron density perturbation and longitudinal wakefield

The laser wake field : broad resonance condition

τ

laser

∼

T

p

/2 => short laser pulse

wave in the wake of a boat

T. Tajima and J. Dawson, PRL 43, 267 (1979)

F=∇I

E

z

= 0.3 GV/m for 1% density perturbation at 10

17

cm

-3

Quasi mono-energetic electron beam

Electron distribution

-

Experimental data

-

3D PIC Simulations

J. Faure et al., Nature 431, 541 (2004)

Experimental parameters : E=1J,

τ

=30fs,

The Bubble regime : distribution quality improvements

SMLWF=>FLWF=>Bubble

Colliding Laser Pulses Scheme

Ponderomotive force of beatwave: F

~ 2a

a

/

λ

(a

et a

can be “weak”)

Boost electrons locally and injects them INJECTION IS LOCAL and IN FIRST BUCKET

Theory : E. Esarey et al., PRL 79, 2682 (1997), H. Kotaki et al., PoP 11 (2004)

Experiments : J. Faure et al., Nature 444, 737 (2006)

The  first  laser  creates  the  accelera,ng  structure

A  second  laser  beam  is  used  to  heat  electrons

Wakefield 

Pump beam 

Injec2on  

beam 

Colliding Laser Pulses Scheme

Ponderomotive force of beatwave: F

~ 2a

a

/

λ

(a

et a

can be “weak”)

Boost electrons locally and injects them INJECTION IS LOCAL and IN FIRST BUCKET

Theory : E. Esarey et al., PRL 79, 2682 (1997), H. Kotaki et al., PoP 11 (2004)

Experiments : J. Faure et al., Nature 444, 737 (2006)

The  first  laser  creates  the  accelera,ng  structure

A  second  laser  beam  is  used  to  heat  electrons

Wakefield 

Pump beam 

Injec2on  

beam 

Injec&on phase 

Colliding Laser Pulses Scheme

Ponderomotive force of beatwave: F

~ 2a

a

/

λ

(a

et a

can be “weak”)

Boost electrons locally and injects them INJECTION IS LOCAL and IN FIRST BUCKET

Theory : E. Esarey et al., PRL 79, 2682 (1997), H. Kotaki et al., PoP 11 (2004)

Experiments : J. Faure et al., Nature 444, 737 (2006)

The  first  laser  creates  the  accelera,ng  structure

A  second  laser  beam  is  used  to  heat  electrons

Wakefield 

Pump beam 

Injec2on  

beam 

Injec&on phase 

Beatwave 

Wakefield 

Pump beam 

Injec2on  

beam 

Injec&on phase 

Beatwave 

Trapped electrons 

Accelera&on phase 

Accelera&on phase 

Towards a Stable Laser Plasma Accelerators

Towards a Stable Laser Plasma Accelerators

Nb: very few electrons at low energy,

δ

E/E=5% limited by the spectrometer

Series  of  28  consecu,ve  shots  wi

th  :

a

=1.5, a

=0.4, n

=5.7×10

cm

Tunability of Laser Plasma Accelerators : electrons energy

Z

=225 μm 

Tunability of Laser Plasma Accelerators : electrons energy

Z

=225 μm 

Z

=125 μm 

Tunability of Laser Plasma Accelerators : electrons energy

Z

=225 μm 

Z

=125 μm 

Z

=25  μm

Tunability of Laser Plasma Accelerators : electrons energy

Z

=225 μm 

Z

=125 μm 

Z

=‐75 μm 

Z

=25  μm

Tunability of Laser Plasma Accelerators : electrons energy

Z

=225 μm 

Z

=125 μm 

Z

=‐75 μm 

Z

=‐175 μm 

Z

=25  μm

Tunability of Laser Plasma Accelerators : electrons energy

Z

=225 μm 

Z

=125 μm 

Z

=‐75 μm 

Z

=‐175 μm 

Z

=‐275 μm 

Z

=25  μm

Tunability of Laser Plasma Accelerators : electrons energy

Z

=225 μm 

Z

=125 μm 

Z

=‐75 μm 

Z

=‐175 μm 

Z

=‐275 μm 

Z

=‐375 

μm 

Z

=25  μm

Mono energetic distribution : 1% relative energy spread

1.5 fs RMS duration : Peak current of 4 kA

Spectral features

Peak at 3

μ

m

Coherent

Analytic CTR model

Gaussian pulse shape

Measured e-beam :

Charge

Energy

Divergence

Bunch duration

Peak wavelength

Peak intensity

O. Lundh et al., Nature Physics, March 2011

1.5 fs RMS duration : Peak current of 4 kA

Spectral features

Peak at 3

μ

m

Coherent

Analytic CTR model

Gaussian pulse shape

Measured e-beam :

Charge

Energy

Divergence

Bunch duration

Peak wavelength

Peak intensity

O. Lundh et al., Nature Physics, March 2011

Cancer treatment improvements : real case of prostate

250 MeV electrons

X rays IMRT

Difference

Y. Glinec, et al., Med. Phys. 33, (1) 155-162 (2006)

T. Fuchs, et al. Phys. Med. Biol. 54, 3315-3328 (2009)

irradiation at 7 angles

Transversal view

sagittal view

Laser-accelerated electrons can provide a better dose sparing of critical

structures (up to 19%) at a similar target coverage compared to photons.

Applications for material science :

γ

radiography

50 μm γ source size 2010

400 μm γ source size 2005

Conclusions

Good beam quality & Monoenergetic dE/E down to 1 %

√

Beam is very stable

√

Energy is tunable: 20-300 MeV

√

Charge is tunable: 1 to tens of pC

√

Energy spread is tunable: 1 to 10 %

√

Ultra short e-bunch : 1,5 fs rms √

Ultra high current e-bunch : 3-4 kA √

Results extremely important for :

Designing future accelerators

Light source development for XFEL

and for applications (chemistry, radiotherapy, material science)

T T T . . TT T T . T T T T T . T T T . . . T . .. .T . . . T T T

Laser Plasma Accelerator : a Wonderful Tool for Science

and for Academic Activities

Acknowledgements

CARE/FP6-Euroleap/FP6-Accel1/ANR-PARIS/ERC contracts

A. Ben Ismail, S. Corde, J. Faure, S. Fritzler, Y. Glinec, A.

Lifshitz, J. Lim, O. Lundh, C. Rechatin, Kim Ta Phuoc, and C.

Thaury from LOA