Bernhard Kliem

Astrophysical Institute Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany

I will present resistive 2D and 3D MHD simulations of spontaneous reconnection that show, depending on parameters, quasi-periodic or very irregular time behavior, the formation of plasmoids or of interlinked flux tubes, and single or double pairs of oppositely directed outflow jets. Generally, the reconnection process evolves in a highly dynamic manner and leads to transient current enhancements exceeding the threshold for onset of anomalous resistivity and, correspondingly, to super-Dreicer electric fields on small scales. Calculations of test particle orbits in the MHD fields will be shown to illustrate some aspects of dc electric field acceleration in reconnection regions, in particular, the different properties of direct acceleration by E|| and of drift and meander acceleration by EL, the maximum particle energy, and the short timescales of the acceleration. Decimetric radio pulsations are finally interpreted as signature of a quasi-periodic reconnection regime.