Parametric study of non-relativistic electrostatic shocks and the structure of their transition layer
2013 (English)In: Physics of Plasmas, ISSN 1070-664X, Vol. 20, no 4, 042111-1-042111-10 p.Article in journal (Refereed) Published
Nonrelativistic electrostatic unmagnetized shocks are frequently observed in laboratory plasmas and they are likely to exist in astrophysical plasmas. Their maximum speed, expressed in units of the ion acoustic speed far upstream of the shock, depends only on the electron-to-ion temperature ratio if binary collisions are absent. The formation and evolution of such shocks is examined here for a wide range of shock speeds with particle-in-cell simulations. The initial temperatures of the electrons and the 400 times heavier ions are equal. Shocks form on electron time scales at Mach numbers between 1.7 and 2.2. Shocks with Mach numbers up to 2.5 form after tens of inverse ion plasma frequencies. The density of the shock-reflected ion beam increases and the number of ions crossing the shock thus decreases with an increasing Mach number, causing a slower expansion of the downstream region in its rest frame. The interval occupied by this ion beam is on a positive potential relative to the far upstream. This potential pre-heats the electrons ahead of the shock even in the absence of beam instabilities and decouples the electron temperature in the foreshock ahead of the shock from the one in the far upstream plasma. The effective Mach number of the shock is reduced by this electron heating. This effect can potentially stabilize nonrelativistic electrostatic shocks moving as fast as supernova remnant shocks.
Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2013. Vol. 20, no 4, 042111-1-042111-10 p.
astrophysical plasma, Mach number, parametric instability, plasma collision processes, plasma electrostatic waves, plasma ion acoustic waves, plasma shock waves, plasma simulation, plasma temperature, supernova remnants
IdentifiersURN: urn:nbn:se:liu:diva-91055DOI: 10.1063/1.4801447ISI: 000318241900013OAI: oai:DiVA.org:liu-91055DiVA: diva2:615964
FunderSwedish Research Council, 2010-4063