Evolution of magnetic helicity in the course of kinetic magnetic reconnection

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 dipo lar structure is related to kinetic current instabilities and becomes domin ant for spontaneous 3D reconnection, in accordance with the dominating curr ent instabilities. The 2D simulations have been carried out with a newly de veloped Vlasov-code and the 3D simulations with the particle-in-cell code G ISMO.