Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Geospace Environment Modeling (GEM) magnetic reconnection challenge: Resistive tearing, anisotropic pressure and Hall effects
Autore:
Birn, J; Hesse, M;
Indirizzi:
NASA, Goddard Space Flight Ctr, Electrodynam Branch, Greenbelt, MD 20771 USA NASA Greenbelt MD USA 20771 Electrodynam Branch, Greenbelt, MD 20771 USA Univ Calif Los Alamos Natl Lab, Space & Atmospher Sci Grp, Los Alamos, NM 87545 USA Univ Calif Los Alamos Natl Lab Los Alamos NM USA 87545 amos, NM 87545 USA
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
fascicolo: A3, volume: 106, anno: 2001,
pagine: 3737 - 3750
SICI:
0148-0227(20010301)106:A3<3737:GEM(MR>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
TEMPERATURE ANISOTROPY; MAGNETOTAIL DYNAMICS; ENERGY RELEASE; SIMULATIONS; FLUID;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
17
Recensione:
Indirizzi per estratti:
Indirizzo: Birn, J NASA, Goddard Space Flight Ctr, Electrodynam Branch, Code 696, Greenbelt, MD 20771 USA NASA Code 696 Greenbelt MD USA 20771 696, Greenbelt, MD 20771 USA
Citazione:
J. Birn e M. Hesse, "Geospace Environment Modeling (GEM) magnetic reconnection challenge: Resistive tearing, anisotropic pressure and Hall effects", J GEO R-S P, 106(A3), 2001, pp. 3737-3750

Abstract

The nonlinear evolution of resistive tearing is studied ire various regimes, including one-fluid isotropic MHD, anisotropic (gyrotropic) MI-ID with terms approximating the effects of anisotropy driven instabilities, and Hall-MI-ID. Both uniform resistivity and spatially localized resistivity are investigated. The initial state is a plane one-dimensional current sheet withan initial perturbation representing a periodic structure with magnetic islands and x type neutral points, chosen for the "GEM magnetic reconnection challenge" [Birn et nl., this issue]. In the absence of dissipation, withinideal MHD, the initially imposed x type configuration collapses into a thin current sheet of finite length, while the magnetic islands contract, conserving their magnetic flux. The current density in the thin sheet becomes significantly enhanced, so that microscopic dissipation mechanisms can be expected to be ignited, even if they were absent in the initial state. Finiteresistivity enables reconnection, and the growth of magnetic islands as inparticle simulations. A comparison of reconnection rates shows that for the chosen initial current sheet thickness, a localized resistivity, corresponding to a Lundquist number (magnetic Reynolds number) of order unity, is necessary to approximate the growth and the reconnection electric field in the particle simulations. Pressure anisotropy, governed by double adiabatic conservation laws (modified by Ohmic heating), lends to reduced growth rates. This reduction is drastic for uniform resistivity. Isotropizing terms, modeling the effects of anisotropy driven microinstabilities again destabilize. Hall-MHD simulations can reproduce the fast growth of the particle simulations. The various models show both similarities and dissimilarities in their spatial structure. For similar amounts of reconnected flux, the variation of the normal magnetic field and of the (ion) how speed along the current sheet are similar, but electric field and current density show significant differences.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 08/04/20 alle ore 09:03:28