报告人：李玉同教授（Chinese Academy of Sciences）
时 间：2014年9月30日（周二）12:15―13:15
地 点：工学院1号楼210会议室
主持人：康炜 特聘研究员

报告简介：
With high-power laser systems, scientists are able to create the extreme conditions of physical experiments in the laboratory presently. Such experimental conditions are unprecedented, and can be used to simulate some representational celestial objects and phenomena, which allow scientists to study many important and critical astrophysical issues in laboratories [1]. In this talk, we will present our recent experimental studies of the interactions between two laser-produced plasma outflows at Shenguang II laser facility, which can delivery energy up to 2 kJ. The main results are below.

1. Magnetic reconnection (MR) is believed to play an important role in many different plasma phenomena including solar flares, star formation, and other astrophysical events. Based on the quasi-steady state of the magnetic fields produced by high power laser pulses, we reconstruct the topology of magnetic reconnection in laboratory by using Shenguang II laser facility. The similar results of loop-top x-ray source in solar flares are observed. By applying the scaling law of magnetohydrodynamics they found the physical parameters of both systems have highly similarity.

2. Most astronomical and astrophysical shock waves are collisionless, which means that the shocks are not formed by coulomb collisions. We will present the generation of collisionless shockwaves in the interaction between two counter-streaming laser-produced plasmas. Numerical simulations indicate that the shockwaves are excited by electrostatic instability. We also observe formation of plasma filaments, which is believed to be caused by Weibel instability.

3. Jet deflection is an interesting astronomical phenomenon that collimated jets usually propagate away from their initial trajectories. When two high-density plasmas jets propagating perpendicular to each other, we observe large angle deflection of the jets. This may throw light on the understanding of the fantastic HH 110/270 system.

References
[1] Bruce A. Remington, R. Paul Drake, and Dmitri D. Ryutov, Rev. Mod. Phys. 78, 755–807 (2006).
[2] J. Y. Zhong, Y.T. Li, X. G. Wang, et al., Nature Physics, 6, 984–987(2010).
[3] X. Liu, Y. T. Li, Y. Zhang, et al., New J. Phys., 13,093001 (2011).
[4] D.W. Yuan, Y.T. Li, X. Liu, et al., High Energy Density Physics 9 239-242 (2013)

报告人介绍：
Yutong Li, Professor of Physics, Institute of Physics, Chinese Academy of Sciences. Group leader in Intense Laser High Energy Density Physics. The main research interests are intense laser-driven particle acceleration and novel radiation, and laboratory astrophysical processes. More than 100 papers has been published (7 on Physical Review Letters and 2 on Nature Physics). He has won the “Distinguished Young Scholar of National Natural Science Foundation”, “Wang Ganchang Award of the Chinese Physical Society”, “Second Class National Natural Science Award” and “Chinese academy of sciences outstanding achievement award”.