Measuring the compression velocity of a Z pinch in an axial magnetic field

This paper presents the results of measuring the velocity of the plasma boundary during the compression of a metallic gas-puff Z pinch in an axial magnetic field. The experiment was conducted on the IMRI-5 facility (current pulse of 450-kA amplitude with a 450-ns rise time); the initial magnetic field B_{z 0} was varied in the range of 0.15-0.6 T. To measure the compression velocity, B-dot probes were used successfully. The data obtained with the B-dot probes agree with the results obtained by other methods [visible imaging and determination of the pinch radius as a function of the time-varying pinch inductance L(t)]. It is shown that the plasma compression velocity is (1-1.5) × 10⁷ cm/s at B_{z 0} = 0 and 0.6 × 10⁷ cm/s at B_{z 0} = 0.6 T.