Spatial Location and Temporal Development of Energetic Electron Beams in 0.45 MA Mo and W X-Pinches

摘要

Summary form only given. Electron beams in X-pinches generated at the CU XP (current 0.45 MA, 50 ns rise time) facility have been studied from measurements of X-rays >9 keV with 1 ns time-resolved filtered and collimated hard X-ray Si diodes. Early three types of electron beams were observed (V. Kantsyrev et al., Rev. Sci. Instr. 75, 3708 (2003)) in X-pinches. Spatial resolution was 0.4 of the anode-cathode X-pinch gap. One diode was pointed at a cross-wire point and another at a region of wires contacts with an X-pinch anode. Softer X-rays were monitored by a PCD detector. Pinhole cameras and an X-ray spectrometer were also applied. During the most discharges, in the cross-wire region the first (1-2 ns duration and correlated with the moment of the first plasma implosion) and the second (2.5-10 ns duration and weakly correlated with soft X-ray bursts) types of electron beams appear. In the anode region, the second and the third (10-30 ns duration, not correlated with any of soft X-ray bursts) types of electron beams were observed. Typically, the intensity of electron beams in a center part of an X-pinch, that appear immediately after the first softer X-ray burst, decreases with current dropping. In opposite, in most discharges, the anode electron beams start about 5-20 ns after the first softer X-ray burst and reached the maximum intensity 20-30 ns later. The different mechanisms of X-pinch electron beams generation are discussed