Laser Plasma Accelerators Principle applications Victor Malka Laboratoire

Laser Plasma Accelerators: Principle & applications Victor Malka Laboratoire d’Optique Appliquée ENSTA-Ecole Polytechnique, CNRS 91761 Palaiseau, FRANCE Partially supported by CARE/PHIN FP 6 project LOA John Adams Insitute, Oxford UK, January 10, 2008

Acknowledgement SPL Particle group ELF Laser group J. Faure Y. Glinec A. Lifschitz C. Rechatin F. Burgy B. Mercier J. Ph. Rousseau Collaborators A. Pukhov, University of Dusseldorf, Germany E. Lefebvre, CEA/DAM Ile-de-France, France LOA John Adams Insitute, Oxford UK, January 10, 2008

Summary Part 1 : Laser plasma accelerator : motivation Part 2 : Laser Plasma accelerator as injector : Production of monoenergetic electron beam Part 3 : New scheme of injection : toward a stable, tuneable and quasi monoenergetic electron beam. Part 4 : Applications Part 5 : Conclusion and perspectives LOA John Adams Insitute, Oxford UK, January 10, 2008

Classical accelerator limitations E-field max ≈ few 10 Me. V /meter (Breakdown) R>Rmin Synchrotron radiation Energy = Length Circle road LEP at CERN 27 km = $$$ ≈ PARIS New medium : the plasma LOA John Adams Insitute, Oxford UK, January 10, 2008 31 km

Why is a Plasma useful ? • Superconducting RF-Cavities : Ez = 55 MV/m • Plasma is an Ionized Medium High Electric Fields Ez ~ w p ~ ne LOA John Adams Insitute, Oxford UK, January 10, 2008

How to excite Relativistic Plasma waves? The laser wake field F≈-grad I Electron density perturbation tlaser≈ Tp / 2 =>Short laser pulse Laser pulse Phase velocity vf =vg => close to c Analogy with a boat epw laser Are Relativistic Plasma waves efficient ? Ez ~ ne Ez = 0. 3 GV/m for 1 % Density Perturbation at 1017 cc-1 Ez = 300 GV/m for 100 % Density Perturbation at 1019 cc-1 Tajima&Dawson, PRL 79 Tajima and Dawson, PRL (1979) LOA John Adams Insitute, Oxford UK, January 10, 2008

Analogy electron/surfer électron t 1 t 2 t 3 ge >> gf >> 1 Emax =2( d n/n) gf 2 mc 2 => Emax (Me. V) ( dn/n)(nc /ne ) L Deph. = lp gf 2 =>L deph. =( l 0 /2)(nc /ne )3/2 Analogy: LOA John Adams Insitute, Oxford UK, January 10, 2008

LOA John Adams Insitute, Oxford UK, January 10, 2008

Classical accelerator limitations Courtesy of W. Mori & L. da Silva 1 m RF cavity LOA John Adams Insitute, Oxford UK, January 10, 2008 100 mm Plasma cavity

Summary Part 1 : Laser plasma accelerator : motivation Part 2: Laser Plasma accelerator as injector : Production of electron beam Part 3 : New scheme of injection : toward a stable, tuneable and quasi monoenergetic electron beam. Part 4 : Applications Part 5 : Conclusion and perspectives LOA John Adams Insitute, Oxford UK, January 10, 2008

Interaction chamber (inside) 50 cm Laser beam electron beam LOA John Adams Insitute, Oxford UK, January 10, 2008

Laser plasma injector Scheme of principle LOA Experimental set up John Adams Insitute, Oxford UK, January 10, 2008

Spatial quality improvements 5. 0 x 1019 cm-3 1. 0 x 1019 cm-3 3. 0 x 1019 cm-3 7. 5 x 1018 cm-3 2. 0 x 1019 cm-3 6. 0 x 1018 cm-3 Divergence = 6 mrad LOA John Adams Insitute, Oxford UK, January 10, 2008

Recent results on e-beam : From Mono to maxwellian spectra Electron density scan V. Malka, et al. , Po. P 2005 LOA John Adams Insitute, Oxford UK, January 10, 2008

Energy distribution improvements: The Bubble regime Charge in the peak : 200 -300 p. C Experiment Divergence = 6 mrad At LOA J. Faure et al. Nature (2004) LOA John Adams Insitute, Oxford UK, January 10, 2008 PIC

Other results RAL & LBNL also to be published tomorrow in Nature 04 50 p. C 300 p. C RAL LOA & John Adams Insitute, Oxford UK, January 10, 2008 LBNL

S. Mangles et al. , C. Geddes et al. , J. Faure et al. , in Nature 30 septembre 2004 LOA John Adams Insitute, Oxford UK, January 10, 2008

Quasi-monoenergetic beams reported in the litterature Name Mangles Geddes Faure Hidding Hsieh Hosokai Miura Hafz Mori Mangles Article Nature (2004) PRL (2006) PRE (2006) APL (2005) PRE (2006) Ar. Xiv (2006) PRL (2006) Lab RAL L'OASIS LOA JETI IAMS U. Tokyo AIST KERI JAERI Lund LC Energy [Me. V] 73 86 170 47 55 11, 5 7 4, 3 20 150 d. E/E [%] 6 2 25 9 10 20 93 24 20 Charge Ne [p. C] [x 1018/cm 3] 22 320 500 0, 32 336 10 432 E-6 200 0, 8 20 19 6 40 40 80 130 28 50 20 Intensity t. L/Tp [x 1018 W/cm 2] 2, 5 11 3 50 22 5 1 0, 9 5 1, 6 2, 2 0, 7 4, 6 2, 6 3, 0 5, 1 33, 4 4, 5 1, 4 Remark Channel Preplasma Several groups have obtained quasi monoenergetic e beam but at higher density (t. L>tp) LOA John Adams Insitute, Oxford UK, January 10, 2008

Ge. V electron beams from a « centimetre-scale » accelerator 310 -μm-diameter channel capillary P = 40 TW density 4. 3× 1018 cm− 3. LOA Leemans et al. , Nature Physics, september 2006 John Adams Insitute, Oxford UK, January 10, 2008

Summary Part 1 : Laser plasma accelerator : motivation Part 2: Laser Plasma accelerator as injector : Production of monoenergetic electron beam Part 3 : New scheme of injection : toward a stable, tuneable and quasi monoenergetic electron beam. Part 4 : Applications Part 5 : Conclusion and perspectives LOA John Adams Insitute, Oxford UK, January 10, 2008

Controlling the injection Counter-propagating geometry: pump Principle: injection Pump beam electrons Injection beam Plasma wave Ponderomotive force of beatwave: Fp ~ 2 a 0 a 1/λ 0 Boost electrons locally and injects them: y INJECTION IS LOCAL IN FIRST BUCKET (a 0 et a 1 can be “weak”)y y E. Esarey et al, PRL 79, 2682 (1997), G. Fubiani et al. (PRE 2004) LOA John Adams Insitute, Oxford UK, January 10, 2008

Experimental set-up to shadowgraphy diagnostic electron spectrometer LANEX B Field Gas jet Probe beam Injection beam Pump beam 250 m. J, 30 fs ffwhm=30 µm I ~ 4× 1017 W/cm 2 a 1=0. 4 LOA 700 m. J, 30 fs, ffwhm=16 µm I ~ 3× 1018 W/cm 2 a 0=1. 2 John Adams Insitute, Oxford UK, January 10, 2008

LOA John Adams Insitute, Oxford UK, January 10, 2008

From self-injection to external injection pump ne=1. 25× 1019 cm-3 Single beam ne=1019 cm-3 Self-injection Threshold ne=7. 5× 1018 cm-3 LOA John Adams Insitute, Oxford UK, January 10, 2008 pump injection 2 beams

Optical injection by colliding pulses leads to stable monoenergetic beams STATISTICS value and standard deviation Bunch charge= 19 +/- 6 p. C Peak energy= 117 +/- 7 Me. V DE= 13 +/- 2. 5 Me. V DE/E= 11 % +/- 2 % Divergence= 5. 7 +/- 2 mrad Pointing stability= 2 mrad *Charge measurements with absolute calibration of Lanex film (ICT gave a factor of 8 higher charge) LOA John Adams Insitute, Oxford UK, January 10, 2008

Monoenergetic bunch comes from colliding pulses: polarization test Parallel polarization Crossed polarization LOA John Adams Insitute, Oxford UK, January 10, 2008

Controlling the bunch energy by controlling the acceleration length By changing delay between pulses: • Change collision point • Change effective acceleration length • Tune bunch energy Injection beam Pump beam 2 mm Gas jet LOA John Adams Insitute, Oxford UK, January 10, 2008

Tunable monoenergetic bunches pump injection Zinj=225 μm Zinj=125 μm late injection pump Zinj=25 μm injection Zinj=-75 μm Zinj=-175 μm middle injection Zinj=-275 μm pump injection Zinj=-375 μm J. Faure et al. , Nature 2006 LOA John Adams Insitute, Oxford UK, January 10, 2008 early injection

Tunable monoenergetic electrons bunches: 190 Me. V gain in 700 µm: E=270 GV/m Compare with Emax=mcwp/e=250 GV/m at ne=7. 5× 1018 cm-3 LOA John Adams Insitute, Oxford UK, January 10, 2008

Summary Part 1 : Laser plasma accelerator : motivation Part 2 : Laser Plasma accelerator as injector : Production of monoenergetic electron beam Part 3 : New scheme of injection : toward a stable, tuneable and quasi monoenergetic electron beam. Part 4 : Applications Part 5 : Conclusion and perspectives LOA John Adams Insitute, Oxford UK, January 10, 2008

Ge. V acceleration in two-stages Laser Gas-Jet Laser Plasma channel Ge. V • 1 J • 10 TW • 30 fs Nozzle • 170± 20 Me. V • 30 fs • 10 mrad • 50 -150 TW • ~50 fs Density profile rc • Pulse guiding condition : Δn>1/πre rc 2 • Weak nonlinear effects more control : a 0 ~ 1 -2 • High quality beams : Lb <λp LOA n 0<1018 cm-3 John Adams Insitute, Oxford UK, January 10, 2008 Δn n 0

Ge. V in low plasma density in plasma channel n 0=8 1016 cm-3, 11 J - 140 TW rc=40 μm, Δn=2 n 0 Electric field d. N/d. E(a. u. ) Electron bunch 4 12 cm 3 2 1 0 Electron bunch 8 cm L channel=4 cm 0 400 800 Energy (Me. V) V. Malka et al. , Plasma Phys. Control. Fusion 47 (2005) B 481–B 490 LOA 1200 John Adams Insitute, Oxford UK, January 10, 2008

Injecting the LOA e-beam @ tbunch = 30 fs, 170 Me. V LOA John Adams Insitute, Oxford UK, January 10, 2008

3 Ge. V, 1% energy spread e-beam l E=9 J l P= 0. 15 PW l l a 0=1. 5 Parabolic channel: l r 0=47 m, l n(r)=n 0 (1+0. 585 r/r 0) n 0 = 1. 1× 1017 cm-3 l 3. 5 Ge. V, with a relative energy spread FWHM of 1% and an unnormalized emittance of 0. 006 mm. LOA V. Malka et al. , PRSTA 9, 091301 2006 John Adams Insitute, Oxford UK, January 10, 2008

Material science: g-ray radiography High resolution radiography of dense object with a low divergence, point-like electron source In collaboration with CEA / DAM LOA Glinec et al. , PRL 94 025003 (2005) John Adams Insitute, Oxford UK, January 10, 2008

g-radiography results 20 mm Cut of the object in 3 D • Measured Calculated Spherical hollow object in Source size estimation : 450 um tungsten with sinusoidal structures etched on the inner part. LOA Glinec et al. , PRL 94 025003 (2005) John Adams Insitute, Oxford UK, January 10, 2008

Particle beam in medicine : Radiotherapy 99% Radiotherapy with X ray LOA John Adams Insitute, Oxford UK, January 10, 2008

Radiation Therapy : context Photon beam Dose Photon beams are commonly used for radiation therapy Photon dose tumor Depth in tissue LOA John Adams Insitute, Oxford UK, January 10, 2008

Medical application : Radiotherapy VHE ELECTRONS LOA John Adams Insitute, Oxford UK, January 10, 2008

l Reduced dose in save cells l Deep traitement l Good lateral contrast VHE Dose VHE Radiation Therapy VHE dose tumor Depth in tissue LOA John Adams Insitute, Oxford UK, January 10, 2008

Clinically approved prostate treatment with seven fields irradiation Transversal view LOA John Adams Insitute, Oxford UK, January 10, 2008 Sagittal view

Improved treatment with electrons A typical transversal dose distribution with 7 beams. Electrons Photons Difference A comparison of dose deposition with 6 Me. V X ray an improvement of the quality of a clinically approved prostate treatment plan. While the target coverage is the same or even slightly better for 250 Me. V electrons compared to photons the dose sparing of sensitive structures is improved (up to 19%). LOA T. Fuchs, DKFZ in preparation John Adams Insitute, Oxford UK, January 10, 2008

Fudamental aspect : fs radiolysis H 2 O e- (e-s, OH. , H 2 O 2, H 3 O+, H 2, H. ) Very important for: • Biology • Ionising radiations effects B. Brozek-Pluska et al. , Radiation and Chemistry, 72, 149 -159 (2005) **Ar. LOA John Adams Insitute, Oxford UK, January 10, 2008

Compact XFEL: towards a bright X ray source Reduction of accelerator Reduction of the undulator 10 cm q ~ mrad Applications: study of complex structures (X-ray diffraction, EXAFS) But ps time scale LOA John Adams Insitute, Oxford UK, January 10, 2008

Parameter designs Laser Plasma Accelerators ELI : > 100 Ge. V a 0=4 P(PW) τ (fs) ne(cm-3) W 0 L(m) E(J) Q(n. C) E(Gev) 0. 12 30 2 e 18 15 0. 009 3. 6 1. 3 1. 12 1. 2 100 2 e 17 47 0. 28 120 4 11. 2 12 300 2 e 16 150 9 3. 6 k 13 112 120 1000 2 e 15 470 280 120 k 40 1120 (μm) Golp and UCLA Group LOA John Adams Insitute, Oxford UK, January 10, 2008

Conclusions / perspectives SUMMARY • Optical injection by colliding pulse: it works ! • Monoenergetic beams trapped in first bucket • Enhances dramatically stability • Energy is tunable: 15 -300 Me. V • Charge up to 80 p. C in monoenergetic bunch • d. E/E down to 5 % (spectrometer resolution), d. E ~ 10 -20 Me. V • Duration shorter than 10 fs. PERSPECTIVES Q • Combine with waveguide: tunable up to few Ge. V’s with d. E/E ~ 1 % • Design future accelerators • Model the problem for further optimization: higher charge • Stable source: extremely important • accelerator development (laser based accelerator design) • light source development for XFEL • applications (chemistry, radiotherapy, material science) LOA John Adams Insitute, Oxford UK, January 10, 2008