1 / 39

Particle acceleration in plasma

Particle acceleration in plasma. By Prof. C. S. Liu Department of Physics, University of Maryland in collaboration with V. K. Tripathi, S. H. Chen, Y. Kuramitsu, L. C. Tai, S. Y. Chen, J. Wang, N. Kumar, and B. Eliasson. Cosmic ray acceleration. Magnetosphere of the Earth.

barclay
Download Presentation

Particle acceleration in plasma

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Particle acceleration in plasma By Prof. C. S. Liu Department of Physics, University of Maryland in collaboration with V. K. Tripathi, S. H. Chen, Y. Kuramitsu, L. C. Tai, S. Y. Chen, J. Wang, N. Kumar, and B. Eliasson

  2. Cosmic ray acceleration

  3. Magnetosphere of the Earth

  4. The Earth’s magnetic field and magnetosphere

  5. Cavity flow with reentrant jet

  6. “Mono-energetic” electrons on the Earth

  7. Electron can be accelerated by plasma wave: Acceleration gradient of plasma wave can be large Maximum acceleration gradient limited by the wave breaking Non-relativistic wave-breaking amplitude or giving, , for SLAC on a slab !!! Relativistic wave-breaking amplitude is the Lorentz factor for plasma wave

  8. How to generate plasma wave ?? Mode conversion Beat wave excitation with two laser pulses Raman scattering Relativistic wake plasma wave excitation by electron beam or short pulse laser

  9. 1) Mode conversion An EM wave obliquely propagates into a plasma with density gradient. + + An oscillatory current can cause space charge oscillations. EM wave → ES wave

  10. 2) Beat wave excitation • Two long laser pulses • Plasma wave excitation possible if, • Maximum saturated amplitude of the plasma wave due to relativistic mass effect Backscattering, Forward scattering, (Rosenbluth and Liu, PRL, 1972)

  11. Nonlinear frequency-amplitude relation

  12. 3) Raman Scattering by Plasma Wave Laser light: Plasma: Scattered light: Feed back Instability Current: Growth rate:

  13. Raman heated electrons

  14. Raman scattering causes electron acceleration

  15. 4) Relativistic wake plasma wave excitation by electron beam or short pulse laser Maximum electric field of the plasma wave

  16. Acceleration of a SLAC electron beam Demonstration of acceleration in beam driven wakefield (SLAC) Hogan et.al. Phys. Rev. Lett. 95, 054802 (2005)

  17. Mono-energetic electron beam by short pulse laser Observation of mono-energetic beam of electrons with energy 50-170 MeV by three groups. Mangles et.al, Nature, 431, 535 (2004), Faure et.al., Nature, 431, 541 (2004), Geddes et.al., Nature, 431, 538 (2004)

  18. First direct measurement of acceleration gradient; eE=2.5 GeV/m ~ 103 of linac. Chen, et.al.(Particle accelerator group, Academia Sinica, NCU)

  19. Laser wakefield acceleration and ion channel formation in laser Micro magnetosphere Relativistic self focusing Laser power, where Relativistic dielectric constant Relativistic effect increases Ponderomotive effect decreases Resultant effect ion channel formation

  20. Electron trajectories

  21. Number density of electrons on axis

  22. Wake field on axis

  23. Experiments at Academia Sinica (PRL, 2006) OOPIC (object-oriented particle-in-cell) code two spatial and three velocity components pre-ionized electron-proton plasma linearly polarized Gaussian laser pulse s-polarization (normal to the density perturbation) moving window immobile ions Parameters Peak laser intensity: I0 = 8x1018 W/cm2(a0 = 2.) Laser wavelength: l = 0.81mm Pulse duration: t = 45 fs Gas density:n = 4x1019/cm3(wp/wL = 0.15) Initial waist size: w0 = 4mm Chirp bandwidth: 27 nm Injection and acceleration of mono-energetic electrons by a self-modulated laser pulse

  24. Initial Plasma Density

  25. Time = 0.735ps

  26. Time = 0.829 ps

  27. Time = 1 ps

  28. Time = 1.1 ps 50 MeV mono energetic electron beam

  29. The wake field bunches the electrons in real space. Time = 1.1 ps

  30. The modulated laser field traps electrons and push electrons moving with the laser pulse. Time = 1.1 ps

  31. The modulated laser field traps electrons and push electrons moving with the laser pulse. (The plasma is turned off at time = 1.33 ps) Time = 1.43 ps 50 MeV mono energetic electron beam Ez of laser pulse

  32. Distribution function

  33. px - x phase space

  34. Ey u- u+ Bz kx Weibel instability Growth rate:

  35. Thank you

  36. Outline • Plasma universe • Plasma wave excitation and trapping of resonant electrons • Laser driven acceleration and production of the mono-energetic electrons beam • Ion acceleration • Concluding remark

  37. Plasma universe Plasma dominated universe Three minutes after Big Bang ----- Radio jets, X-ray sources, g-ray bursts, pulsar, accretion disk etc…. We observe our universe mostly by EM waves. Its dispersion relation,

  38. Ion bubble formation by different a

More Related