Microstructure in two- and three-dimensional hybrid simulations of perpendicular collisionless shocks

0464290 - ÚFA 2017 RIV US eng J - Journal Article
Burgess, D. - Hellinger, Petr - Gingell, I. - Trávníček, Pavel M.
Microstructure in two- and three-dimensional hybrid simulations of perpendicular collisionless shocks.
Journal of Plasma Physics. Roč. 82, č. 4 (2016), 905820401/1-905820401/23. ISSN 0022-3778. E-ISSN 1469-7807
Institutional support: RVO:68378289
Keywords : ion-acceleration * numerical simulations * bow shock * electron acceleration * cluster observations * self-reformation * magnetic-field * whistler waves * injection * nonstationarity
OECD category: Fluids and plasma physics (including surface physics)
Impact factor: 1.160, year: 2016
https://www.cambridge.org/core/journals/journal-of-plasma-physics/article/microstructure-in-two-and-three-dimensional-hybrid-simulations-of-perpendicular-collisionless-shocks/F964EF89FB14A6504A49CFAD54970E2B

Supercritical collisionless perpendicular shocks have an average macrostructure determined primarily by the dynamics of ions specularly reflected at the magnetic ramp. Within the overall macrostructure, instabilities, both linear and nonlinear, generate fluctuations and microstructure. To identify the sources of such microstructure, high-resolution two-and three-dimensional simulations have been carried out using the hybrid method, wherein the ions are treated as particles and the electron response is modelled as a massless fluid. We confirm the results of earlier two-dimensional (2-D) simulations showing both field-parallel aligned propagating fluctuations and fluctuations carried by the reflected-gyrating ions. In addition, it is shown that, for 2-D simulations of the shock coplanarity plane, the presence of short-wavelength fluctuations in all magnetic components is associated with the ion Weibel instability driven at the upstream edge of the foot by the reflected-gyrating ions. In 3-D simulations we show for the first time that the dominant microstructure is due to a coupling between field-parallel propagating fluctuations in the ramp and the motion of the reflected ions. This results in a pattern of fluctuations counter-propagating across the surface of the shock at an angle inclined to the magnetic field direction, due to a combination of field-parallel motion at the Alfven speed of the ramp and motion in the sense of gyration of the reflected ions.
Permanent Link: http://hdl.handle.net/11104/0263256