Proton Beam Acceleration with Circular Polarized Laser Pulses

Transcription

1 New Orleans, Louisiana May 2012 Proton Beam Acceleration with Circular Polarized Laser Pulses X.Q.Yan Institute of Heavy Ion physics, Peking University, China Center of Applied Physics and Technology, Peking Univeristy Peking Univ.: J.E.Chen, X.T.He, C.Lin, H.Y.Wang, S.Zhao, J.Zhu, H.Z.Fu, Y.Shang, K.Zhu, Z.Wang, Y.R.Lu, Z.Y.Guo Shanghai Jiaotong Uni.(China)/IOP: Z.M.Sheng, Y.T.Li, L.M. Chen, J.Zhang MPQ/LMU: T.Tajima, J. Meyer-ter-Vehn, D.Habs, J. Schreiber,R.Hoerlein, A.Henig, D.Kiefer, D.Jung IZEST/LOA: G.Mourou LANL: M. Hegelich, H.C.Wu, L.Yin 1

2 Outline 1. Why laser plasma accelerator 2. Phase Stability Acceleration (PSA) in a laser plasma accelerator 3. Challenges of PSA acceleration 4. Future plan at Peking University 2

3 Livinston Chart LHC RAL LBL 1GeV by few cm Capillary in 2006 LBL Acc Gradient of Laser plasma accelerator is 100GV/m! 3

4 Laser Plasma Wake Accelerator (LWPA) 1979 Tajima and Dawson propose LWPA. John M Dawson( ) Toshiki Tajima 4

5 1GeV mono-energetic electron beam Divergence(rms): 1.6 mrad Energy spread (rms): 2.5% Resolution: 2.4% Charge: 35 pc Nature physics VOL.2, (Leemans et al )

6 0.8 GeV mono-energetic electron beam Cascaded Laser Wakefield Acceleration Using Ionization-Induced Injection Z. Z. Xu et al. PRL 107, (2011) Shanghai Institute of Optics and Fine Mechanics 6

7 Target Normal Sheath Acceleration (TNSA) Ions are much more heavier than electrons, the plasma wake field can hardly trap and accelerate slow ions! They are mainly accelerated from solid targets by TNSA so far. Electric Field: >TV/m!!! Acc length is only few microns Phys. Rev. Lett. 85, 2945 (2000). Phys. Plasmas 18, (2011) 7

8 Target Normal Sheath Acceleration (TNSA) Maximum proton energy 60 MeV in 2000 and 68 MeV in 2011, moreover the spectrum is still exponential! Phys. Rev. Lett. 85, 2945 (2000). Phys. Plasmas 18, (2011) 8

9 Laser Driven Microlens Focus and Energy-Select Mega Electron Volt Protons T.Toncian et al., SCIENCE, 312,410, 2006 High energy and low energy spread? 9

10 Micro-structured target reducing the energy spread, still MeV energy Hegelich et al., Nature 439, 441 (2006) H. Schwoerer, et al. Nature 439, 445 (2006). High energy and low energy spread? 10

11 Outline 1. Why laser plasma accelerator 2. Phase Stability Acceleration (PSA) in a laser plasma accelerator 3. Challenge of PSA acceleration 4. Future plan at Peking University 11

12 2. Phase Stability Acceleration (PSA) Radiation Pressure Acceleration B.Shen et. al., PRE, VOLUME 64, (2001) A. Macchi, et al, Phys. Rev. Lett. 94, (2005) Xiaomei Zhang, et al, PHYSICS OF PLASMAS 14, (2007) X.Q.Yan et al, PRL, 100, (2008) Rykovanov, et al, NJP. 10, (2008) Klimo et al, PRST 11, (2008) Robinson et al, NJP 2008 M. Chen et al., Phys. Rev. Lett. 103, (2009). A.Henig et al. PRL 103, (2009) p x Circular Polarized (CP) pulse + nanometers foil Mono-energetic ion beam 0.45 t=50t L x/λ L Synchrotron oscillation 12

13 Ponderomotive force Linear polarized laser f E f p = p E L v L ( x) = m = v 4 x 2 L ( x)(sin( ω t) yˆ + cos( ω t) zˆ) m = v 4 x 2 L ee L L ( x) xˆ / mω L ( x)(1 cos 2ω t) xˆ Circular Polarized laser L L 15 circular polarization 10 linear polarization b x/λ L No oscillation component, it pushes electrons forward! p x 1D simulation a=5, n 0 /n c =10, L=0.2λ 13

14 Phase Stable Acceleration model CP laser pulse electron proton Electrons are pushed forward and pile up in the front of a CP laser pulse. Protons are nearly fixed Skin depth: l s, target thickness d+ ls 14

15 Phase Stability Acceleration when a ~( n / n ) D/ λ 0 c L ΔW W r 2ξ 0 Ω / p = l Ω / p r A s r B p x 0.16 t=18t L 0.12 Phase space (x~p x ) A x/λ L Ω B Ex1 = E0 x/ d,(0 < x< d) E = 4π nd 0 0 E = E (1 ( x d)) / l, ( d < x< d + l ) x2 0 s s X.Q.Yan et al, PRL 100, (2008) 15

16 Phase motion is harmonic Motion equations: d x qe 2 i i 0 = (1 ( x ) / ) 2 3 i d ls dt miγ 2 d xr qe r 0 = (1 ( x ) / ) 2 3 r d ls dt miγ p x 0.16 t=18t L x/λ L Phase motion equation: ξ = Ω ξ, Ω 2 2 = qie m l γ i s 0 3 ξ = ξ0 sin( Ωt) or proton/ions γ~1, The phase motion is harmonic with frequency Ω The energy spread is derived: Δw/ w 2 ξ Ω/ r 0 p 16 r

17 Phase oscillations in Simulations p x 0.16 t=18t L 0.25 t=26t L a=5, n 0 /n c =10, L=0.2λ, τ=100 T L p x p x x/λ L 100x/λ L t=36t L x/λ L N(Arb.Unit) a) D 2D Energy(MeV) ΔW W r Ions are trapped in the bucket! 2ξ 0 Ω / p = l Ω / p r s r The periods are 8, 8 and 10 T L X.Q.Yan et al CHIN.PHYS.LETT. Vol. 25, No. 9 (2008)

18 Phase stability (1944) p x Phase space (x~p x ) 0.16 t=18t L A B Photo by U. Amaldi Particles are compressed in the phase space! N(Arb.Unit) a) x/λ L 1D 2D Energy(MeV)

19 Sail model for PSA acceleration Sailboat PSA Electron--- Sail Proton--- Boat Laser ---Wind 19

20 Conversion Efficiency (CE) CE=1- ~100% 20

21 Self-organizing GeV proton in Phase Stable regime (a) t=16 I~10^22W/cm2 (b) t=36 ε r ~0.5 mm.mrad (c) t=42 Arb.Unit 60 t=40 T t=50 T t=54 T t=58 T (b) γ-1 X.Q.Yan, W.H.C, Z.M.Sheng,J.E.Chen, J.MtV, et al., PRL, 103, , (2009) 21

22 Demonstration of PSA a ~( n / n ) D/ λ 0 c L I~5*10^19W/cm2,5nm DLC foil 13MeV proton; 30MeV carbon 22

23 Optimum thickness of DLC is 5nm a ~( n / n ) D/ λ 0 c L PSA has rigorous request on laser contrast! 23

24 Demonstration of PSA a ~( n / n ) D/ λ 0 c L I~10^20W/cm2 5nm DLC foil 40MeV carbon 24

25 Outline 1. Why laser plasma accelerator 2. Phase Stability Acceleration (PSA) in a laser plasma accelerator 3. Challenges of PSA acceleration 4. Future plan at Peking University 25

26 RPA Challenge (I): High Laser Intensity Maximum Proton Energy (MeV) E19 1E20 1E21 1E22 Laser intensity I (W/cm 2 ) 1000MeV proton beam, I ~10^22W/cm^2 Contrast>10^11@~ps 100MeV proton beam, I ~10^21W/cm^2 Contrast>10^10@~ps 13~30MeV Experimental demonstration T.Tajima, D.Habs, and X.Q.Yan. Review of Accelerator Science and Technology, 2( ),

27 Laser pulse front breaks the foil nm foil Laser front Breaks the foil!!! Contrast = peak intensity / intensity at laser front 27

28 RPA Challenge (II) : Contrast of 10 It is very difficult to satisfy a contrast >10 and an intensity of W/cm 2! m ain pulse Power TW Intensity W/cm 2 Contrast in ps SILEX-I <10 6 QG-III ( 上海 ) <10 6 pedestal ASE Tim e 1. Amplified Spontaneous Emission 2. Pedestal:100ps before the main pulse LANL, USA MBI, Germany JAERI, Japan <10 6 XL-II <10 6 Astra

29 RPA Challenge (III): Hole boring and Instabilities Hole boring M.Chen et al PoP, 15, , 2008 M.Hegelich and L.Yin Klimo et al, Phys. Rev. ST AB 11, (2008) A P L Robinson et al 2008 New J. Phys

30 Challenges in PSA regime High laser intensity High contrast >10^21W/cm2 Hole boring and instabilities: Short rise time (1~3T) is required Quasi-Step function pulse profile!!! 30

31 How can we accelerate proton more efficiently? Ultrathin solid target 31

32 use a critical dense plasma as a lens Plasma Lens Ultrathin solid target H. Y. Wang, C.Lin et al., PRL 107, (2011) 32

33 Plasma lens to generate high quality laser pulses Plasma Lens Ultrathin solid target H. Y. Wang et al., PRL 107, (2011) 33

34 Laser driven plasma lens Plasma lens nm foil 1. Pulse cleaning 2. Intensity 20 times higher 3. pulse steepening at the same time for a short pulse!!! 34

35 Theoretical prediction: >100MeV >200TW, 25fs,5~25J laser H.Y.Wang, X.Q.Yan, et al., submitted (2012) 35

36 Outline 1. Why laser plasma accelerator 2. Phase Stability Acceleration (PSA) in a laser plasma accelerator 3. Challenges of PSA acceleration 4. Future plan at Peking University 36

37 LAser proton accelerator (LAPA) at PKU PSA Power supply: >200TW, 25fs,5~25J laser commercial product from Thales or AT company, costs ~2M$ Plasma lens 37

38 Applications of LAPA (10~100MeV ) 1)Cancer therapy >200TW,25fs,5J~25J 2)ICF fast ignition ) diagnostic for HEDP 4) Proton Imaging 5) HIB for ITER 6)Injector for HEP accelerator 38

39 DLC Target Manufacture System (CAD) We have successfully manufactured Diamond-like Carbon (DLC) foil with thickness between 5~40nm. Coating DLC NaCl Film stripping Water Get out of water Frame Si Image of DLC foil DLC foil & NaCl layer Coating machining Measurement of atomic force microscope 39

40 Summary Phase Stability Acceleration (PSA) can generate mono-energetic ion beam. 10~30MeV quasi-monoenergetic Carbon/proton beam were demonstrated in the experiments. Laser Plasma lens can be used to realize high laser intensity and high contrast! A prototype of 10~100MeV proton accelerator (LAPA) will be built at Peking University in the near future. 40

41 Thanks for your attention! Thanks NSFC and Humboldt Foundation for financial support! 41

42 Mountain of Laser Plasma Accelerator average power γγ collider 1KW By T.Tajima rep rate 42