Using of B-dot probe for z-pinch plasma diagnostics

Abstract

We present experiments performed on the IMRI-5 generator (450 kA, 450 ns) with a metallic gas-puff Z-pinch with a power-law density profile. The experiments were carried out in a preembedded axial magnetic field Bz0 that was varied from 0 to 0.6 T. To determine the initial pinch radius r0, we used the function r(t) that was found from the time dependence of the pinch inductance L(t). The time-dependent inductance L(t), in turn, was determined as a function of load voltage Vload(t) and pinch current I(t). The function r(t) was verified by a B-dot probe diagnostics. Measurements showed that for the “first shot” the initial radius of the metallic gas-puff Z-pinch decreased from 4 cm at Bz0 = 0 to 2.1-1.7 cm at Bz0 = 0.15 T. We believe that the decrease it r0 is related to the field effect on the ion gyroradius.