Cathode Plasma Jet Pinching and Intense X-Ray Emission in a Moderate-Current Laser-Triggered Vacuum Discharge

Occurrence of cathode plasma jet pinching and its dependence on anode-cathode separation (d=2-10 mm) in a moderate-current (~10 kA) low-energy (les 20 J) vacuum discharge is presented. Discharge was created between a planar titanium cathode and a conical point-tip titanium anode by producing plasma on the cathode using 27-ps-duration laser pulses. For d=2-3 mm, constricted flow of cathode plasma jet up to anode was observed along with multiple feeble local pinchings. A neck formation was observed for d=5-6 mm, whereas multiple pinching occurred for larger separations. Temporal profiles of the X-ray emission from the anode due to bombardment by electrons extracted from the expanding cathode plasma, for different anode-cathode separations, were consistent with the characteristics of cathode plasma jet pinching