Experiments on the MM-4U, MM-2 and HER mirrors

Three lines of experiments on open confinement systems have been followed which are concentrated on the key issue of experimental investigation of various MHD stabilization methods in axisymmetric end cells. (1) MM-4U is a small tandem mirror with cusp end cells. By use of electron beam injection from the ends to build the plasma, a negative potential plasma has been formed and preliminary measurements of the axial potential profile have been carried out. (2) After formation of a hot electron ring in the MM-2 simple mirror, the spatial distribution of hot electrons and ECRH trapping of an electron beam have been investigated. (3) The stabilizing effect of line tying of the conducting wall on the interchange mode is studied in the HER mirror. (author). 2 refs, 6 figs