Strong magnetic fields generated with a metal wire irradiated by high power laser pulses and its effect on bow shock
Authors: Li Yan-Fei  , Li Yu-Tong  , Zhu Bao-Jun  , Yuan Da-Wei  , Li Fang  , Zhang Zhe  , Zhong Jia-Yong  , Wei Hui-Gang  , Pei Xiao-Xing  , Liu Chang  , Yuan Xiao-Xia  , Zhao Jia-Rui  , Han Bo  , Liao Guo-Qian  , Lu Xin  , Hua Neng  , Zhu Bao-Qiang  , Zhu Jian-Qiang  , Fang Zhi-Heng  , An Hong-Hai  , Huang Xiu-Guang  , Zhao Gang  , Zhang Jie  ,   Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China;,   Department of Astronomy, Beijing Normal University, Beijing 100875, China;,   National Laboratory on High Power Lasers and Physics, Shanghai Institute of Optics and Fine Mechanical, Chinese Academy of Sciences, Shanghai 201800, China;,   Shanghai Institute of Laser Plasma, China Academy of Engineering Physics, Shanghai 201800, China;,   Laboratory for Laser Plasmas(Ministry of Education) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China;,   Collaborative Innovation Centre of IFSA, Shanghai Jiao Tong University, Shanghai 200240, China;,   School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Laboratory astrophysics is a rapid developing field studying astrophysical or astronomical processes on a high-power pulsed facility in laboratory. It has been proved that with the similarity criteria, the parameters in astrophysical processes can be transformed into those under laboratory conditions. With appropriate experimental designs the astrophysical processes can be simulated in laboratory in a detailed and controlled way. Magnetic fields play an important role in many astrophysical processes. Recently, the generation of strong magnetic fields and their effects on relevant astrophysics have attracted much interest. According to our previous work, a strong magnetic field can be induced by a huge current formed by the background cold electron flow around the laser spot when high power laser pulses irradiate a metal wire. In this paper we use this scheme to produce a strong magnetic field and observe its effect on a bow shock on the Shenguang II (SG II) laser facility. The strength of the magnetic field is measured by B-dot detectors. With the measured results, the magnetic field distribution is calculated by using a three-dimension code. Another bunch of lasers irradiates a CH planar target to generate a high-speed plasma. A bow shock is formed in the interaction of the high-speed plasma with the metal wire under the strong magnetic condition. The effects of the strong magnetic field on the bow shock are observed by shadowgraphy and interferometry. It is shown that the Mach number of the plasma flow is reduced by the magnetic field, leading to an increase of opening angle of the bow shock and a decrease of the density ratio between downstream and upstream. In addition, according to the similarity criteria, the experimental parameters of plasma are scaled to those in space. The transformed results show that the magnetized plasma around the wire, produced by X-ray emitted from the laser-irradiated planar target in the experiment, is suitable for simulating solar wind in astrophysics. In this paper, we provide another method to produce strong magnetic field, apply it to a bow shock laboratory astrophysical study, and also generate the magnetized plasma which can be used to simulate solar wind in the future experiments.