Τίτλος:
Two-dimensional PIC simulations of ion beam instabilities in Supernova-driven plasma flows
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
Supernova remnant blast shells can reach the flow speed vs = 0.1c and shocks form at its front. Instabilities driven by shock-reflected ion beams heat the plasma in the foreshock, which may inject particles into diffusive acceleration. The ion beams can have the speed vb ≈ vs. For vb ≪ vs the Buneman or upper-hybrid instabilities dominate, while for vb ≫ vs the filamentation and mixed modes grow faster. Here the relevant waves for v b ≈ vs are examined and how they interact nonlinearly with the particles. The collision of two plasma clouds at the speed v s is modelled with particle-in-cell simulations, which convect with them magnetic fields oriented perpendicular to their flow velocity vector. One simulation models equally dense clouds and the other one uses a density ratio of 2. Both simulations show upper-hybrid waves that are planar over large spatial intervals and that accelerate electrons to ∼10 keV. The symmetric collision yields only short oscillatory wave pulses, while the asymmetric collision also produces large-scale electric fields, probably through a magnetic pressure gradient. The large-scale fields destroy the electron phase space holes and they accelerate the ions, which facilitates the formation of a precursor shock. © 2008 IOP Publishing Ltd.
Συγγραφείς:
Dieckmann, M.E.
Meli, A.
Shukla, P.K.
Drury, L.O.C.
Mastichiadis, A.
Περιοδικό:
Plasma Physics and Controlled Fusion
Λέξεις-κλειδιά:
Ion bombardment; Plasma diagnostics; Two dimensional, Flow speeds; PIC simulations; Supernova (SN); supernova remnants; Two-dimensional (2D), Plasma stability
DOI:
10.1088/0741-3335/50/6/065020
