Investigation of pinch dynamics in plasma-focus discharges by means of fast-streak-and fast-frame-cameras

Abstract

In order to investigate the Plasma-Focus (PF) pinch dynamics within the large PF-1000 facility the use was made of fast streak-and frame-cameras operated as the routine optical diagnostic tools. They enabled images of a current-sheath (CS) layer and the PF-pinch to be recorded within the visible range (VR) at chosen instants of the investigated PF-discharges. The measurements were carried out end-and side-on the PF-1000 electrode system under different experimental conditions. For the temporal synchronization of both cameras with the chosen phases of the PF discharge, we used current derivative (dI=dt) waveforms and X-ray signals recorded for each shot. During the described PF-1000 experiments, we performed also other complimentary measurements. Particular attention was paid to studies of current-and voltage-waveforms of the investigated discharges, to a comparison of the total neutron yields measured by means of silver activation counters, and to the analysis of time-resolved neutron-and X-ray-signals recorded with several scintillation detectors. Results of the observations carried out with the fast streak-and frame-cameras, which were compared with other experimental studies, allowed better understanding of all the PF-discharge phases to be achieved. In particular, the correlation of different quantum-and corpuscular-radiation pulses, which has influence on the total fusion-neutron yield, has been analyzed.