Stuttgart 2012 – scientific programme
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SYGP: Symposium Gemeinsame Probleme in Fusions- und astrophysikalischen Plasmen
SYGP 3: Contributed Talks
SYGP 3.5: Talk
Monday, March 12, 2012, 17:30–17:45, V55.22
The effect of small guide fields on the stability and bifurcation of collisionless current sheets — Kuang Wu Lee1, Jörg Büchner1, and •Frank Jenko2 — 1Max-Planck-Institut für Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany — 2Max-Planck-Institut für Plasmaphysik, Garching, Germany
Our recent investigation of modified Harris current sheet shows that, indeed, a current sheet bifurcation instability dominated by the electron dynamics. In the course of the nonlinear instability evolution a bifurcated current sheet structure is naturally evolving from an unstable single-peaked current sheet [Lee & Büchner 2012]. In space plasmas, however, in addition to the anti-parallel magnetic field that maintains the current sheet equilibrium, embedded current-aligned guide fields have to be taken into account. The understanding of the guide field influence on the current sheet bifurcation, which should be considered in the electron kinetic scale, is nevertheless poor. In fusion research typically very strong guide fields are present in the current direction. However, very often at the Sun and in the heliosphere the guide fields are relatively small, of the order of the antiparallel components. Also, instead of the commonly assumed single-peaked current concentrations frequently bifurcated current sheets (BCS) were observed. Hence, we conducted two-dimensional particle-in-cell (PIC-) code simulations to investigate the influence of a relatively small guide field on the stability of current sheets and the formation of BCS. A statistical mechanics analysis of the influence of a guide field dependence will be presented, and the electron dominant turbulent process will be discussed.