Abstract
Astrophysical collisionless shocks are amazing phenomena in space and astrophysical plasmas, where supersonic flows generate electromagnetic fields through instabilities and particles can be accelerated to high energy cosmic rays. Until now, understanding these micro-processes is still a challenge despite rich astrophysical observation data have been obtained. Laboratory astrophysics, a new route to study the astrophysics, allows us to investigate them at similar extreme physical conditions in laboratory. Here we will review the recent progress of the collisionless shock experiments performed at SG-II laser facility in China. The evolution of the electrostatic shocks and Weibel-type/filamentation instabilities are observed. Inspired by the configurations of the counter-streaming plasma flows, we also carry out a novel plasma collider to generate energetic neutrons relevant to the astrophysical nuclear reactions.
Highlights
High power lasers can create extreme conditions in the laboratory relevant to astrophysical systems[1,2,3]
Scaling law[4], it presents a new route, laboratory astrophysics, to investigate the astrophysical scenarios, such as shock generation in supernova explosions[5], magnetic reconnection occurring at solar flares[6, 7], and Herbig–Haro objects associated with young stellar object formation[8]
A sharp edge appears in the interaction region where the exploded matters with high velocity penetrate through the rare interstellar mediums (ISMs), indicating that a shock is formed
Summary
Scaling law[4], it presents a new route, laboratory astrophysics, to investigate the astrophysical scenarios, such as shock generation in supernova explosions[5], magnetic reconnection occurring at solar flares[6, 7], and Herbig–Haro objects associated with young stellar object formation[8]. The shock transition region is measured about 0.04 pc (= 1.2 × 1017 cm), 1/400 of the mean free path (MFP ∼ 13 pc)[10] It is collisionless and mediated by the collective effect, instead of the Coulomb collisions. This shock has attracted much interest in its formation mechanism, generation/amplification of the magnetic fields[11, 12], and the spray of the energetic cosmic rays[13,14,15]. No matter which scheme is applied, it must achieve the collisionless conditions between CPFs, i.e., the MFP larger than the interaction scale, L (target separation or shock transition width, in our experiment L = 4.5 mm). Inspired by the configuration of the CPFs, we perform an exploratory experiment relevant to neutron astrophysics to distinguish between collisionless and collisional effects in CPFs
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