Vortices and flux ropes in Electron MHD plasmas II

Laboratory experiments are reviewed which continue to describe novel proper ties of three-dimensional (3D) vortices in Electron MHD (EMHD) plasmas. The se include the collision of vortices which produces no nonlinear interactio n since their electromagnetic fields are force-free (J x B+ neE similar or equal to 0). Nonlinearities arise when the vortex field exceeds the backgro und magnetic held and produces magnetic null points where EMHD breaks down. Dc magnetic fields are produced by vortices of alternating polarities. Mag netic reconnection at 3D null points changes the field topology on the fast whistler time scale. In a high-beta plasma (beta > 1) pressure-gradient dr iven instabilities near the lower hybrid frequency are observed to form elo ngated magnetic vortices (flux ropes) coupled to flute-like density striati ons.