Magnetic field line reconnection in the current systems of flux ropes and Alfvén waves

Magnetic field line reconnection is still considered, by some, to be one of the most important topics in plasma physics. It has been in this category for close to 30 years and the ‘problem of reconnection’ has still not been solved. Magnetic field topologies are part and parcel of the current systems within a plasma whatever their source. Plasma currents may initially be induced or injected but they soon become entangled or part of the currents of plasma waves, flows and structures. We first present experimental results of undriven reconnection, which occurs when two magnetic flux ropes are generated from initially adjacent pulsed current channels in a background magnetoplasma (length 18m, diameter 60 cm). The second example presented is the three-dimensional (3D) magnetic fields and currents associated with colliding laser-produced plasmas. The currents in this situation are those of shear Alfvén waves. The wave magnetic field is a small fraction of the background field; nevertheless, reconnection regions, multiple magnetic ‘X’ points (which are 3D) and induced electric fields are observed. The first involves the interaction of magnetic flux ropes and the second localized reconnection sites in the current system of Alfvén waves. PACS numbers: 96.60.lv, 47.32.cf, 52.35.Vd (Some figures in this article are in colour only in the electronic version.)