Laser-driven proton acceleration from cryogenic hydrogen jets

Transcription

1 Laser-driven proton acceleration from cryogenic hydrogen jets new prospects in tumor therapy and laboratory astroparticle physics C. Roedel SLAC National Accelerator Laboratory & Friedrich-Schiller-University Jena S. Goede, M. Gauthier, J. Kim, M. MacDonald, W. Schumaker, S. Glenzer HED Science Dept., SLAC National Accelerator Laboratory R. Mishra, C. Ruyer, F. Fiuza HED Theory Group, SLAC National Accelerator Laboratory K. Zeil, L.Obst, M. Rehwald, F. Brack, R. Gebhardt, U. Helbig, J. Metzkes, H.-P. Schlenvoigt, P. Sommer, T. Cowan, U. Schramm Helmholtz-Zentrum Dresden-Rossendorf, Germany

2 Motivation laser driven proton acceleration Ion beam therapy - Bragg peak MeV protons are stopped in 25 cm 2

3 Motivation laser driven proton acceleration Ion beam therapy - Bragg peak MeV protons are stopped in 25 cm Small bandwidth, 200 MeV protons beams are required 3

4 Motivation laser driven proton acceleration Heidelberg Ion Therapy Center Proton therapy using conventional ion accelerators - Large scale facilities - Cost: 120 M Laser-driven proton acceleration - Target Normal Sheath Acceleration (TNSA) compact laser system reduced costs proton energies are too low broadband spectrum single shot proton source multispecies ion acceleration K. Zeil U. Schramm 4

5 Motivation High Energy Density Science at SLAC Particle Acceleration Intense Laser Laboratory Fusion Laboratory Astrophysics Energetic Protons C. Roedel M. Gauthier S. Glenzer F. Fiuza Pure hydrogen target of solid density would be perfect!!! 5

6 A cryogenic hydrogen jet for HED experiments Cryostat Liquefied H 2 (18 K, 10 μm) Source Assembly 20 μm Cylindrical solid-density hydrogen target Hydrogen Jet S. Goede 6

7 A cryogenic hydrogen jet for proton acceleration experiments K. Zeil U. Schramm S. Goede C. Roedel M. Gauthier 7

8 Proton acceleration from solid-density hydrogen jets Hydrogen jet

9 Proton acceleration from solid-density hydrogen jets

10 Proton Beams Target Normal Sheath Acceleration (TNSA)

11 Experiment at HZDR: Proton acceleration using a solid-density hydrogen jet Cryostat B Thomson Parabola Ion Spectrometer E X-rays protons 7 MeV f/3 OAP Hydrogen Hydrogen Jet Jet f/3 OAP Short Pulse Laser 4 J in 27 fs W/cm 2 Optical Alignment + Scattering Diagnostic Accelerated Protons Laser protons/mev/sr J et proton spectrum Higher proton energies in laserforward direction 45 TP 0 TP proton energy in MeV 11

12 Experiment at HZDR: Proton acceleration using a solid-density hydrogen jet Cryostat B Thomson Parabola Ion Spectrometer E X-rays protons 7 MeV pure proton spectrum f/3 OAP Hydrogen Jet Accelerated Protons proton acceleration with 1 Hz Short Pulse Laser 4 J in 27 fs W/cm 2 Optical Alignment + Scattering Diagnostic Laser J et 12

13 Quick summary of laser proton acceleration Solid density hydrogen jet as a target for laser proton acceleration Pure proton beams accelerated by TNSA ~10 MeV protons with 1 Hz <0.002 mm mrad which is at least 100 times smaller than the emittance of thermal ion sources [T. Cowan et al. Phys. Rev. Lett. 92, (2004)] T. Cowan S. Glenzer Emittance is compelling for a novel injector scheme TNSA spectrum is not useful for most applications, monoenergetic spectrum and higher proton energies required 13

14 Motivation Collisionless Shock Acceleration for Monoenergetic Proton Acceleration 200 TW drive beam Hydrogen jet Collisionless Shock Acceleration may lead to better energy scaling # ions [arb. units] F. Fiuza et al. Phys. Rev. Lett. 109, (2012) F. Fiuza et al. Phys. Rev. Lett. 108, (2012) Ion energy [MeV/a.m.u.] 14

15 Collisionless Shock Acceleration and the role of the Weibel instability [ pi -1 ] Ion density <Density> B-field Weibel instability generates B-fields locally F. Fiuza et al. Phys. Rev. Lett. 108, (2012) F. Fiuza February 24, 2015 Stanford 15 University

16 Motivation Collisionless Shock Acceleration and Laboratory Astroparticle Physics SN1006 Tycho Downstream turbulence Vd Upstream waves Vu dn/de E - N. Gehrels, L. Piro, and P.J.T. Leonard, Scientific American (2002) R. Blandford & D. Eichler, Physics Reports 154, 1 (1987) 16

17 Radiochromic film shows bubble-like structure in forward-accelerated beam Cryostat B Thomson Parabola Ion Spectrometer E X-rays protons 7 MeV Hydrogen Jet f/3 OAP RCF stack 20 E= MeV E= MeV Short Pulse Laser 4 J in 27 fs W/cm 2 Optical Alignment + Scattering Diagnostic 0 Laser J et -20 Bubble-like structure in forward accelerated proton beam 17

18 Optical probe provides estimate of the length of the plasma density gradient Cryostat B Thomson Parabola Ion Spectrometer E X-rays protons 7 MeV Hydrogen Jet f/3 OAP RCF stack Probe only Delay: -5 ps Delay: 0 ps Short Pulse Laser 4 J in 27 fs W/cm 2 Optical Probe Diagnostic Laser 5 m J et 6 m 10 m Length of plasma density gradient: L p =5 m 18

19 2D PIC simulation using experimental parameters reveals Weibel instability proton density R. Mishra F. Fiuza Modulation of the proton density in the rear side density gradient Modulation in the B-field might be due to the Weibel instability 19

20 2D PIC simulation using experimental parameters reveals Weibel instability Current density at early times (100 fs) =3 Γ= v c c ω pe n c np C. Ruyer et al. Physics of Plasmas 22, (2015) Counter streaming currents go Weibel unstable Weibel filament size is local plasma wavelength 20

21 2D PIC simulation using experimental parameters reveals Weibel instability E x -field B z field TNSA accelerated protons pass the Weibel B-fields 22

22 Agreement between simulations and experimental results RCF plane Ion density (a.u.) Simulated beam profile E p > 1 MeV Spacing: mm Deflection (mm) RCF lineout Ion dose (a.u.) Measured beam profile Spacing: 1-5 mm Deflection (mm) 22

23 3D PIC simulations reproduce experimental results Netlike structure is reproduced in 3D simulations Caustic formation requires B fields from Weibel instability of the order of 100 MG Can we observe Collisionless Shock Acceleration? 24

24 Experiment at Titan laser at LLNL Proton Spectrum from 10μm H 2 Jet at 5x10 19 W/cm2 Monoenergetic features in laser-forward direction that cannot be explained by TNSA Radiation pressure driven shock velocity matches 1 MeV peak 24

25 Quasi-monoenergetic features in the proton spectrum appear to be from Collisionless Shockwave Acceleration Proton Spectrum from 10μm H 2 Jet at 5x10 19 W/cm2 Proton Phase Space from 2D PIC Simulation 4.3 Re ected Ions Approximate Energy (MeV) Shock front reflects ions, producing a quasi-monoenergetic MeV peak A second peak appears to due to the accumulation of protons along the shock front Onset of Collisionless Shock Acceleration might be observed in addition to Weibel radiograph 25

26 Summary Laser particle acceleration for medical applications proton acceleration up to 10 MeV by TNSA from cryogenic solid-density hydrogen plasma laser-driven proton accelerator with 1 Hz Laboratory astroparticle physics proton radiography of magnetic fields due to Weibel instability quasi-monoenergetic spectral features may reveal onset of Weibel-mediated Collisionless Shock Acceleration experimental platform for studies of magnetic field amplification and Collisionless Shock Acceleration using femtosecond high intensity lasers 26

27 Outlook: Observation of collisionless shock acceleration and Weibel instabilities using x-ray free-electron lasers

28 Observation of Weibel instabilities using x-ray free-electron lasers Laser target

29 Observation of Weibel instabilities using x-ray free-electron lasers B-field Density

30 Observation of Weibel instabilities using x-ray free-electron lasers

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32 X-ray laser

33 Phase-contrast imaging

34 Reconstructed density profile Phase-contrast imaging

35 Cryogenic hydrogen jets and high power lasers provide new opportunities to investigate magnetic field amplification and Collision Shock Acceleration in the laboratory Thank you for your attention!