1. How long can one ignore this? Groupe d’Accélération par Laser et Ondes Plasma Recent Developments und Future Challenges in Laser-Wakefield (Plasma) Acceleration Laboratoire Leprince-Ringuet Ecole Polytechnique, Palaiseau W.P. Leemans, et al., Nature Phys. 2, 696-699 (2006) 10 8 e – de 0 à 1 GeV ±2.5% en 3cm

2. introduction and basic concepts present and future challenges for plasma accelerators recent developments in laser plasma accelerators present and future plans

3. why get interested in laser acceleration?  LINACS: energy = gradient  length  long machines  LASERS: progression in intensity  technology breakthrough énergie faisceau [eV] 100 GeV année de mise en service RF accelerators (e - /e + ) LASERS Int. [W/cm2] 19-FEB-20083CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France)

4. what is a plasma wave? Periodic variation (in x and t) of the electron density n e ! sound waveplasma wave (fully or partly) ionized gaz electrostatic interaction: long range force neutral molecular gaz collisions : short range force sound speed plasma frequency: The plasma wave is accompanied by a strong electric field 19-FEB-20084CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) (forn e =10 19 cm -3 )

5. plasma wave excitation  laser beat wave (PBWA) 1st generatiom, long laser pulses O(ns)  self-modulated laser wakefield (SMLWFA) long laser pulse, non-linear plasma wave  linear laser wakefield (LWFA) short laser pulse (CPA, Ti-Sapphire: O(30fs))  « plasma » wakefield(PWFA) short e-/e+ bunch (UCLA/SLAC: 40  80GeV)  blowout- (bubble-, cavitation-) regime  n e /n e > 1, massive auto-injection of plasma e – 19-FEB-20085CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) ponderomotive force (figure-eight movement of plasma electrons) F   I laser pulse: v G  c  n/n plasma wave: v P= v G  c  P /c

6. scaling laws in linear regime  optimisation for P LASER = P crit (relativistic autofocussin) fixes n e free parameters:  P, laser pulse power, laser wavelength   = ∆n e /n e plasma wave amplitude  scaling laws [example: =800nm, P=1PW,  =0.2]  plasma wave-length: P ~ ·P 1/  = 200µm  max. longitudinal field: E z ~ -1 ·P -1/  ·  = 17GV/m  dephasaging length: L  ~ ·P  /  = 11m  max. energy gain: ∆W ~ P= 170GeV  increase P LASER at fixed pulse energy  reduce pulse duration  not considered:  beam-loading : modification of plasma wake field by the field of the bunch  pump-depletion : laser pulse energy drops as it propagates  multi-stage acceleration 19-FEB-20086CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France)

7. 7 major breakthrough in 2004: bubble regime four groups reach “bubble” regime (a.k.a. blowout or cavitation)  in LWFA: RAL (UK), LOA (France), LBL (US)  in PWFA: UCLA/SLAC (US) “energy doubling” of SLAC beam total blowout of plasma electrons self-injection of plasma electrons behind wake 19-FEB-20087CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) Wei Lu (UCLA), AAC2006, Lake Geneva

8. high-gradient electron acceleration in the bubble regime 19-FEB-20088CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) J. Faure et al., Nature 431, 541–544 (2004) J.M. Hogan et al., Phys. Rev. Lett. 95, 054802 (2005) LWFA (LOA, France)PWFA(SLAC/UCLA) self-injection of plasma electrons:  very nonlinear  induces fluctuations  hard to control / lack of flexibility  not reproducible: 1 out of 3-5 shots

9. particle-in-cell (PIC) simulation of self-injection into bubble 19-FEB-20089CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) Wei Lu (UCLA), AAC2006, Lake Geneva (USA)

10. laser – plasma acceleration activities worldwide o LOA: Laboratoire d’Optique Appliquée (ENSTA) o LULI: Laboratoire d’Utilisation des Lasers Intenses (Polytechnique) o CEA/DSM/DRECAM/SPAM (Saclay) o LPGP: Laboratoire de Physique des Gaz et Plasmas (Orsay) o Et bientôt: L’Institut de la Lumière Extrème (ILE) strong concentration in south-west Paris area 19-FEB-200810CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) slide courtesy of V. Malka

11. introduction and basic concepts present and future challenges for plasma accelerators recent developments in laser plasma accelerators present and future plans

12. klystron  high power laser (ultra-short pulse) E=O(10J), τ=O(10fs)  P=O(10PW)  repetition rate 0.1-1Hz  10-100 kHz  wall-plug efficiency few %  few 10% RF cavity  gas jet, gas cell, gas-filled capillary, capillary discharge (n  10 17 -10 19 cm -3 ) stability :  maîtrisé  (contre-propagatif) laser guiding : beam-loading, pump-depletion laser coupling at capillary entry RF wave  plasma wave ( P  10-100µm) régime: linear, wave-breaking, bubble (blow-out) transverse emittance: focussing  longitudinal emittance: energy dispersion ∆E/E,  T, stability: ion movement, useful plasma wave buckets  decrease size of « accelerating structure » increase the accelerating gradient: form RF to plasma waves 19-FEB-200812CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France)

13. present and future challenges for laser plasma accelerators parameters of beam bunch: charge,  position ,  angle ,  energy , energy spread, transverse emittance, bunch duration LWFAILCunit  increase energy  increase acceleration length 0.2–1250GeV  increase charge  high gas density? external injection? 0.01– 0.1 3nC  reduce bunch spacing  laser rep. rate: “10Hz”, multi plasma-wave buckets? 0.1–10370.10 -9 s  energy spread (“monochromaticity”) 1%0.1%  bunch duration  «bane or blessing for colliders?», difficult to measure <3 (?) 300µm  transverse emittance <3 (?)19/0.07mm.mra d  stability and control of Q, x’,E (“reproducibility”) 19-FEB-200813CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France)

14. energy frontier: increase acceleration length  plasma wave (and laser) guidingl’onde:  auto-focalisation in gas cell or jet  « laser-drilled » plasma channels  gas-filled (passive) capillaries  capillary discharge (refr. index gradient)  laser 40 TW, n e =4.3×10 18 cm −3 (LBL, 2006)  self-injection regime (= plasma bubble plasma)  capillary discharge  ~0,3mm,L~30mm  stable opération at 450 MeV W.P. Leemans, et al., Nature Phys. 2, 696-699 (2006) 30mm 0.20.60.81.00.4 E [GeV] 19-FEB-200814CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France)

15. introduction and basic concepts present and future challenges for plasma accelerators recent developments in laser plasma accelerators present and future plans

16. D. Umstadter et al, PRL 76, 2073 (1996); E. Esarey et al, PRL 79, 2682 (1997) pump injection controlling stability: external injection using a 2nd laser pulse 19-FEB-2008CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France)16  counter-propagating geometry not necessarily head-on, 135º works  ponderomotive force of beatwave: F P ~ 2a 0 a 1 /λ 0 (a 0 et a 1 can be “weak”)  boost electrons locally and injects them:  injection is local in first PW bucket  linear : no need of self-focusing, no self-trapping plasma wave pump beam injection beam electrons Electron motion Buckets at p figures courtesy of J. Faure

17. colliding pulse injection: experimental setup 19-FEB-200817CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) animation courtesy of C. Rechatin

18. Electron beam Injection beam Pump beam colliding pulse injection: experimental setup (2008)  LASER  TiSaph: 50TW 30fs  2 beams a 0 =1.3 a 1 =0.6  non-collinear angle=7º  <1 shot/ 10sec  gas jet  length = 3mm  e - density n e =3.10 18 –2.10 19 cm -3 (via pressure ) 19-FEB-200818CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France)

19. colliding pulse injection: tuning the beam energy (LOA,2006) plasma wave pump beam injection beam electrons  2 impulsions contra-propagatives laser existant: 30fs, ~1J, ~30TW faisceau pompe: 700mJ faisceau injection: 250mJ  injection contrôlée d’e- dans plasma: ajustement de l’énergie Z inj =225 μm Z inj =125 μm Z inj =25 μm Z inj =-75 μm Z inj =-175 μm Z inj =-275 μm Z inj =-375 μm pump injection late injection pump injection middle injection pump injection early injection J Faure et al 2007 Plasma Phys. Control. Fusion 49 B395-B402 19-FEB-200819CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) J.Faure et al., Nature 444, 737-739

20. colliding pulse injection: controlling the phase-space volume  control phase space volume of injection by changing pump pulse intensity (a 1 )  take into account beam-loading : bunch charge distorts the plasma wake electric field  energy– charge correlation 19-FEB-200820CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) C. Rechatin et al., Phys. Rev. Lett. 102, 164801 (2009) C. Rechatin et al., Phys. Rev. Lett. 103, 194804 (2009)

21. colliding pulse injection: energy stability of 30 consecutive shots 19-FEB-200821CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) V. Malka, Workshop on The Physics and Applications of High Brightness Electron Beams Maui, Hawaii – November 16-19, 2009

22. 184MeV 3.3% (RMS) 5.4pC 170MeV 1.8% 4.5pC 165MeV 6.8% 9.9pC 154MeV 3.5% 8.0pC 167MeV 2.4% 2.4pC 176MeV 4.4% 7.6pC 182MeV 2.9% 8.2pC 177MeV 3.3% 17.1pC l20n87 1.5J_4. bars_6.5A l20n88 1.5J_4. bars_6.5A l20n89 1.5J_4. bars_6.5A l20n90 1.5J_4. bars_6.5A l20n91 1.5J_4. bars_6.5A l20n92 1.5J_4. bars_6.5A l20n93 1.5J_4. bars_6.5A l20n94 1.5J_4. bars_6.5A colliding pulse injection: energy stability of 8 consecutive shots 150MeV200MeV 19-FEB-200822CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) A. Ben Ismail, Advanced Accelerator Concepts, 2008, Santa Cruz, USA

23. l20n277i4 l20n223i6 l20n97i6 1.5J_4.bars_6.A 1.5J_4.bars_6.5A - assuming 3mrad divergence. - deduced from direct measurements on the screen Error bars colliding pulse injection: observation of sub-percent E-spread 1.5J_4.bars_6.A 1.5J_4.bars_6.5A B 19-FEB-200823CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) 1.9% 1.3% 0.9% A. Ben Ismail, Advanced Acceclerator Concepts, 2008, Santa Cruz, USA

24. 19-FEB-2008CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France)24 design of a high resolution magnetic spectrometer  quadrupole triplet (FODOF,  |dB/dx|dz = 1.2T) + permanent dipole (  Bdz = 0.36T Tm)  E resolution <1% over 100-150 MeV over 100-400MeV range  2 energy ranges: 100-220 MeV, 220-1200MeV  2 phosphor screens  avoid resolution degradation by multiple scattering  transport in vacuum  stigmatic imaging for particular energy values  in general: astigmatic  divergence estimation  E resolution shot to shot

25. 19-FEB-2008CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France)25 design performance of the high resolution spectrometer 1% low E screen high E screen 1% low E screen high E screen E/MeV spot size [mm] dispersive magnet plane non-dispersive magnet plane 100MeV150MeV low E quad. setting high E quad. setting 0500 0 0 0 A. Ben Ismail

26. undulator experiment at LOA (2009/2010) 19-FEB-200826CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France) compactified beam transport line

27. introduction and basic concepts present and future challenges for plasma accelerators recent developments in laser plasma accelerators present and future plans

28. Near term plans  injection of plasma generated beam into an undulator (under way)  also:caracterisation of the modified beam transport line  increase accélération length  capillary discharge, acceleration length  20mm  E  1GeV  single laser pulse and colliding pulse injection  further improvement of high resolution spectrometer  prepare transverse emittance measurement (at ~ 100–200 MeV)  motivation: emittance supposed to be small  high luminosity (one day) transverse size of accelerating zone << laser spot (plasma simulations )   N,x   x   x    20  m/10  3mrad  350  2 mm.mrad  what physics determines the transverse emittance?  can one efficiently control the phase space volume at injection?  small repetition rate & strong shot-to-shot fluctuations of beam parameters  need single-shot measurement (phase-space sampling, MS / PP) 19-FEB-200828CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France)

29. present et future context  LOA : «salle jaune» laser 40TW, 30fs improvements in 2011, dedicated experimental zones  CEA (SPAM) : IRAMIS UHI 100TW 30fs, 2 salles  ILE (Institut de la Lumière Extrême)  located in south-west Paris area  two lasers: LUIRE: 1PW, 15fs, 0.1Hz,1st light 2012? APOLLON:10 PW, 15fs, 0.01 Hz, 2014?  applications: e -. p, XFEL  GALOP contributes to « systems control » workpackage, management, experiments  ELI (Extreme Light Infrastructure)  international installation  10 fois ILE (100PW)  on roadmap de ESFRI 19-FEB-200829CLIC Meeting (CERN) : Arnd Specka (LLR, Ecole Polytechnique, Palaiseau, France)