DYNAMICS OF A PLASMA FORMED BY EXPLODING METAL WIRES AND INSULATOR FIBERS

High-current nanosecond discharges through metal wires and insulator f ibres were investigated in the NIKE-3 (100 kA, 50 ns) and BIN (250 kA, 100 ns) facilities. Glass fibres were used as an example in a study o f the dependence of the discharge conditions on the linear density mu of the load. An increase in mu altered the nature of the discharge thr ough the diode from a mismatched regime accompanied by generation of a n electron beam (mu < 4 mug cm-1) to the formation of 'hot spots' (mu = 8-20 mug cm-1) and then to a regime of a luminous skin layer (mu > 3 0 mug cm-1). A strong influence of the state of the surface on the nat ure of an explosion of a metal wire was observed. The experimental res ults obtained at the beginning of wire explosions were accounted for b y a model of the metal-plasma transition. The plasma motion and the de velopment of instabilities of a plasma filament during a discharge wer e investigated by optical methods. Some of the experiments indicated s imultaneous development of helical and 'sausage' instabilities. A two- dimensional ideal magnetohydrodynamic model was employed in calculatio ns dealing with the process of formation of a constriction (pinching) and the results were in good agreement with the observations.