Studies of laser-driven magnetic reconnection & collisionless shockwaves

1. Studies of laser-driven magnetic reconnection & collisionless shockwaves Yutong Li National Laboratory of Condensed Matter Physics Institute of Physics, Chinese Academy of Sciences, Beijing • Session 1P2 • 5:30 - 5:45 pm Jiayong Zhong • 5:45 - 6:00 pm Yutong Li • Session 2A2 • 12:15 - 12:30 pm Quan-Li Dong April 30-May 4 HEDLA 2012

2. National Lab. of Condensed Matter Physics, CAS (Y. T. Li, Q. L. Dong, et al.) National Astronomical Observatories (G. Zhao, J. Y. Zhong, F. L. Wang, et al.) Shanghai Jiao Tong U. (J. Zhang, et al. ) National Laboratory on High Power Lasers and Physics (J. Q. Zhu, et al.) CAEP(W. D. Zheng, J. Y. Zhang, Y. K. Ding, et al) Peking U. (X. G. Wang et al.) ILE, Osaka U., Japan (H. Takabe, H. Nishimura, Y. Sakawa, et al.) Korea Atomic Energy Research Institute (Yong-Joo Rhee, et al.) Our research team

3. Outline • Laser- driven magnetic reconnection (LDMR) • Collisionless shockwaves formed by two counter-streaming plasmas

4. B field measured by proton radiography Toroidal B field 1.2 ns C. K. Li et al., Phys. Rev. E. 80, 016407 • Toroidal B fields are • Mega Gauss (100 T) • Concentrated on a hemispherical bubble • Surrounding and expanding Magnetic fields in laser-plasma interactions (~100T) Thermal electric source ~Texne J. A. Stamper etal, PRL, 34,138 (1975)

5. Constructing LDMR • Magnetic reconnection occurs • Magnetized plasmas encountered each other • With oppositely pointed B-fields Front view Side view

6. LDMR examples X-point Gold Nilson et al., PRL 97, 255001 (2006) Yates et al., PRL, 49,1702 (1982) X-ray emission Optical probe

7. LDMR examples Au foil or D 3He-filled capsule Laser on from 0 – 1 ns 5 mm 0.04 ns 0.67 ns 1.42 ns C. K. Li et al., PRL 99, 055001 (2007) L. Willingaleet al., PoP 17, 043104 (2010) Proton probe

8. Magnetic reconnection jets in solar flares MR model is used to explain thesolar flare bursts. Yohkoh/SXT

9. Astronomical observed evidence for MR model --- loop-top hard x-ray source Masuda, S, et al. A loop-top hard X-ray source in a compact solar flare as evidence for magnetic reconnection. Nature 371, 495-497 (1994). Can we simulate the astronomical x-ray sources in lab.?

10. Shenguang II • Optical shadowgraphy and interferometry • X-ray imagers: • Pinhole cameras • framed camera Shenguang II Laser: Pump: 8 beams(2kJ, 1ns, 3) Probe: 9th beam (2 , 70 ps)

11. Modeling loop-top X-ray source with the MR jets Laboratory Solar flares • Jets in parallel with the target surface are observed. • Similar hard x-ray source to the astronomical is formed due to the down jet interacting with another target J. Y. Zhong, et al., Nature Physics 6, 984 (2010)

12. Competition between MR and collision? Diffusion structure of LDMR? Particle acceleration by LDMR ?

13. d 200 m 400 m 600 m X-ray framing images for interaction of two plasma bubbles ―Competition between MR and collision 1. Changing the distance of two plasma bubbles d

14. 2. Anti-parallel and parallel magnetic line of force Anti-parallel Parallel Only collision MR dominates

15. ― The structures of diffusion region Two- dimensional/3-component Hall MHD Simulations • Ion diffusion region with the width of ~di • Electron diffusion region with the width of ~10de

16. ― Acceleration of particles in LDMR MR? High energy cosmic x-ray spectrum

17. 430G EM spectrometer Spectral distribution ―Electron measurements IP Stack spatial distribution E >550 keV Dong et al PRL 2012 (accepted)

18. Outline • Laser- driven magnetic reconnection (LDMR) • Collisionless shockwaves formed by two counter-streaming plasmas

19. Supernova Remnant SN1006 Shell : Collisionless Shock 　 ⇨ Generation of high-energy particles, origin of cosmic-ray 　 ⇨ Acceleration by collisionless shocks

20. Two catalogues • In lab. collisionless shockwaves driven by • High intensity relativistic laser pulses (fs-ps, >1018W/cm2) • High energy laser pulses (ns, kJ, 1015W/cm2)

21. Experiment Setup 4 laser beams for generating shock Pinhole camera 2 Neutral Filter Band pass filter CH Target CCD Glan prism 9th beam 2 , 70ps, 50 mJ CH Target 100um thick Wollaston prism 3° Nomarski Interferometer CCD Pinhole camera 1 SG II 8 laser beams with 2 kJ total energy, 1ns pulse duration, @ 3  (351nm) to generate shocks Pump Pump Imaging Probe The distance between the targets was 4.5 mm. The delay between the main beam and probe can be changed from 0 ns to 13ns. 2, 70 ps Pump Pump

22. Experiment results（4+0 laser beams ) Density jump The ion mean free path is ~25-35mm，far larger than the density jump region (100um) Collisionless shock 9 ns 5 ns

23. Experiment results （4+4 laser beams ) Density jump 1 ns 2 ns Plasma filaments 3 ns 5 ns

24. Distribution of the electron to ion temperature ratio Te is much higher than Ti A 2D hydrodynamic code was used to simulate the CH plasma generation Electron density distribution along the center of the target

25. The linear dispersion relation of the electrostatic mode: The linear growth rate of the electrostatic ion-ion instability The linear growth rate of the electromagnetic Weibel-type instability 1)The strength of electrostatic (ES) instability is larger than the Weibel (EM) instability at the beginning. 2)The wavelength of ES is smaller than that of EM.

26. Discussions • From calculation and PIC simulations, it is deduced that the density jump at early time was probably an electrostatic collisionless shock. • The wavelength of Weibel type instability is much closer to the size of the filaments observed at later time (for example, 5 ns). The filaments may be caused by the Weibel instability. X. Liu, et al., New J. Phys. 13, 093001 (2011)

27. 100 μm 2 mm 1 ns t0 1.5 ns 1 ns t1 2.0 ns 120 ps t2 Instabilities induced by two non-identical plasmas （a） Probe ( t2) CH 3 beams (t1) 350 μm 150 μm 4 beams (t0) 4.5mm （b） Rayleigh-Taylor instability?

28. Summary • With high power laser facility, • Spatial- and temporal-resolved structure and particle acceleration of LDMR have been observed • Shock waves and instabilities have been investigated in the interaction of two counter-streaming plasmas • In future experiment , We will concentrate on the acceleration physics related to MR, shocks and jets. Thanks!

29. Two plasmas in different systems Laser Plasmas Solar flare Plasmas Rm = 5108 Rm = 4000 Scaling Law Ideal MHD equations

30. Contributors China J. Zhang, Y. T. Li, Q. L. Dong, Y. Zhang, S. J. Wang, X. Liu, Z. M. Sheng, et al., Institute of Physics (IOP), CAS Shanghai Jiao Tong University (STJU) G. Zhao, J. Y. Zhong, F. L. Wang, J. R. Shi, H. G. Wei, L. Di, et al., National Astronomical Observatories J. Y. Zhang, Y. K. Ding, B. H. Zhang, L. Zhang, Y. J. Tang, et al, Research Center for Laser Fusion, CAEP J. Q. Zhu, Y. Gu, et al., ，National Laboratory on High Power Lasers and Physics, Shanghai Japan H. Takabe, H. Nishimura, S. Fujioka, Y. Sakawa, T. Kato, Y. Kuramitsu et al., Institute of Laser Engineering, Osaka University Korea Yong-Joo Rhee, et al., Korea Atomic Energy Research Institute

31. 无碰撞冲击波的实验室研究 □ 实验中的等离子体凸变区域尺度约为350μm □ 由 计算对流等离子体中离子平均自由程为110cm □2 ns时密度变化主要是由于两个等离子体之间的无碰撞机制产生的

32. PIC simulation of collisionless shocks 0.9 c wall Reflection of the plasma by the wall ⇨Production of counter-streaming plasma simulation by T. Kato Number density Upstream region Downstream region Mass Ratio: mp/me = 20 Velocity: V = 0.9c Transition region Magnetic field is ~1% of the kinetic energy of the bulk plasma in the upstream region Magnetic fieldElectric field Strong magnetic field in the transition region provides an effective dissipation x Kato, T. N. & Takabe, H. 2008, ApJ, 681, L93 Kato, T. N. & Takabe, H. 2010, Phys. Plasmas, 17, 032114

33. Comparison of the dimensionless parameters of the shock in a SNR with the experimental X. Liu, et al., New J. Phys. 13, 093001 (2011)