Generation of Electric Currents in Two-dimensional Magnetic Nulls

Abstract

view Abstract Citations (3) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Generation of Electric Currents in Two-dimensional Magnetic Nulls Fontenla, Juan M. Abstract We present detailed calculations and results for a model case of two-dimensional small distortions of static, current-free equilibrium around a null-line magnetic configuration. This setup has been studied for fast energy release in flares, but has not been studied before in the context of the magnetic energy buildup that precedes the flare. Our analytical results are new because they include gas pressure and provide explicit formulae for the expressions of all quantities (and especially the electric current) and energy storage as functions of the values of boundary conditions. A general solution is shown as a combination of eigenfunctions, with coefficients resulting from the boundary conditions. These boundary conditions are given in terms of any arbitrary plasma acceleration at a boundary enclosing the domain we study. The approach used here studies the MHD evolution of the electric current and plasma density variations driven by external forces. We find that both pressure and Lorentz forces are important, and that their boundary values select between a wide range of solutions, many of which have been found previously in numerical simulations. Most of the modes we find display strong current sheets, velocities, and pressure variations at the separatrices Also we find that Joule and other dissipative terms are not important for typical cases, except at an extremely narrow inner core, and near the separatrices We discuss our results and their relationship to numerical MHD simulations. Publication: The Astrophysical Journal Pub Date: December 1993 DOI: 10.1086/173535 Bibcode: 1993ApJ...419..837F Keywords: MAGNETOHYDRODYNAMICS: MHD; SUN: MAGNETIC FIELDS full text sources ADS |