NPG Nonlinear Processes in Geophysics NPG Nonlin. Processes Geophys. 1607-7946 Copernicus Publications Göttingen, Germany 10.5194/npg-8-127-2001 Evolution of magnetic helicity in the course of kinetic magnetic reconnection Wiegelmann T. 1 2 Büchner J. 1 Max-Planck-Institut für Aeronomie, Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany School of Mathematics and Statistics, University of St. Andrews, St. Andrews, KY16 9SS, United Kingdom 30 06 2001 8 3 127 140 Copyright: © 2001 T. Wiegelmann 2001 This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Generic License. To view a copy of this licence, visit https://creativecommons.org/licenses/by-nc-sa/2.5/ This article is available from https://npg.copernicus.org/articles/8/127/2001/npg-8-127-2001.html The full text article is available as a PDF file from https://npg.copernicus.org/articles/8/127/2001/npg-8-127-2001.pdf

We investigate the evolution of magnetic helicity density in the course of 2D and 3D kinetic magnetic reconnection through thin current sheets. In 2D, the helicity density near a reconnection X-line becomes purely quadrupolar structured, while in 3D, an additional dipolar structure occurs. This dipolar structure is related to kinetic current instabilities and becomes dominant for spontaneous 3D reconnection, in accordance with the dominating current instabilities. The 2D simulations have been carried out with a newly developed Vlasov-code and the 3D simulations with the particle-in-cell code GISMO.