Full particle-in-cell simulation of the interaction between two plasmas for laboratory experiments on the generation of magnetized collisionless shocks with high-power lasers

Abstract

A preliminary numerical experiment is conducted for laboratory experiments on the generation of magnetized collisionless shocks with high-power lasers by using one-dimensional particle-in-cell simulation. The present study deals with the interaction between a moving Aluminum plasma and a Nitrogen plasma at rest. In the numerical experiment, the Nitrogen plasma is unmagnetized or magnetized by a weak external magnetic field. Since the previous study suggested the generation of spontaneous magnetic field in the piston (Aluminum) plasma due to the Biermann battery, the effect of the magnetic field is of interest. Sharp jumps of electron density and magnetic field are observed around the interface between the two plasmas as long as one of the two plasmas is magnetized, which indicates the formation of tangential electron-magneto-hydro-dynamic discontinuity. When the Aluminum plasma is magnetized, strong compression of both density and magnetic field takes place in the pure Aluminum plasma during the gyration of Nitrogen ions in the Aluminum plasma region. The formation of a shock downstream is indicated from the shock jump condition. The result suggests that the spontaneous magnetic field in the piston (Aluminum) plasma plays an essential role in the formation of a perpendicular collisionless shock.

High-power laser experiment forming a supercritical collisionless shock in a magnetized uniform plasma at rest

“…Previous experiments have revealed that even in the unmagnetized case, selfgenerated magnetic field (i.e., Biermann field) is crucial in the ion reflection [26], which plays an important role in the formation of perpendicular shocks. This is also indicated by one-dimensional (1D) PIC simulation [27].…”

“…We recorded the scattered light of ion feature with an intensified charge-couple device (ICCD) with 3 ns exposure time. In this paper, we discuss the role of self-generated field (via Biermann battery effect) in Al plasma [27]. Unfortunately, there was no direct measurement of magnetic fields in this experiment to conclusively indicate that the Biermann field is playing an important role.…”

Collisionless Shocks Driven by Supersonic Plasma Flows with Self-Generated Magnetic Fields

“…Shock formation and particle acceleration have previously been studied for various astrophysical and laboratory conditions in many PIC simulations [8][9][10]31,[33][34][35][36][37]. They do not, however, fully reproduce our experimental conditions for which the expanding shell plasma carrying selfgenerated magnetic field interacts with a fast-moving plasma jet.…”

“…2(b)]. We attribute the source of the upstream magnetic fields in zone III to be the Biermann battery effect [30,31]. Hydrodynamic simulations indicate that such fields are generated in the expanding shell plasma.…”

The Discrepancy Between Simulation and Observation of Electric Fields in Collisionless Shocks

“…More typical values for the latter fall in the ∼2-4 range for recent simulations (Umeda et al, 2014;Matsukiyo and Matsumoto, 2015;Zeković, 2019). However, much larger values have been used in cases where one can reduce the simulation to one spatial dimension (Umeda et al, 2019). Despite all of the progress made since the early full PIC simulations, there still remains two striking discrepancies between observations and many simulations: the amplitude and wavelength at which the strongest electric fields are observed and inconsistencies in the thickness of the shock ramp.…”