HR: 1340h
AN: SH43A-1085    [Abstracts]
TI: PIC simulations of reforming perpendicular shocks- implications for ion acceleration at SNRs and the heliospheric termination shock
AU: Lee, R E
EM: leer@astro.warwick.ac.uk
AF: Space and Astrophysics, University of Warwick, Coventry, CV4 7AL United Kingdom
AU: * Chapman, S C
EM: sandrac@astro.warwick.ac.uk
AF: Space and Astrophysics, University of Warwick, Coventry, CV4 7AL United Kingdom
AU: Dendy, R O
EM: R.O.Dendy@ukaea.org.uk
AF: Euratom/UKAEA Fusion, Culham, Oxon, OX14 3DB United Kingdom
AB: Recent particle-in-cell (PIC) simulations have revealed time-dependent shock solutions for parameters relevant to astrophysical and heliospheric shocks [e.g. 1,2,3]. These solutions are characterised by a shock which cyclically reforms on the spatio-temporal scales of the incoming protons. Whether a shock solution is stationary or reforming depends not only upon the model adopted for electron dynamics, but also on the plasma parameters, notably the upstream beta. For the heliospheric termination shock, these parameters are not well determined: some estimates suggest that the termination shock may be in a parameter regime such that it is time-dependent. It has been pointed out [3] that this may terminate some acceleration processes, for example shock surfing, which have been proposed for time-stationary shock solutions. The introduction of time-dependent electromagnetic fields intrinsic to the shock does however introduce the possibility of new mechanisms for the acceleration of protons. We will discuss the prospects for local ion acceleration at reforming quasiperpendicular shocks, in the presence of pickup ions as seen in selfconsistent PIC simulations with parameters relevant to both SNRs and the heliospheric termination shock. [1] Shimada, N., and M. Hoshino, Astrophys. J, 543, L67, 2000. [2] Schmitz, H., S.C. Chapman and R.O. Dendy, Astrophys. J, 570, 637, 2002 [3] Scholer, M., I. Shinohara and S. Matsukiyo, J. Geophys. Res., 108, 1014, 2003
DE: 7807 Charged particle motion and acceleration
DE: 2104 Cosmic rays
DE: 2114 Energetic particles, heliospheric (7514)
DE: 2124 Heliopause and solar wind termination
DE: 3210 Modeling
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting