Formation of single pinched plasma point in the cathode plasma jet of a multipicosecond laser-triggered vacuum discharge

Characteristics of cathode plasma jet pinching and x-ray emission from a multipicosecond laser-triggered vacuum discharge are presented. Discharge was created in between a planar Al cathode and a conical point-tip Ti anode (separation: 2-15 mm, circuit inductance of ∼0.53 μH, peak discharge current of ∼3 kA, and rise time of ∼400 ns). For anode-cathode separation of ∼13.5 mm, only a single pinched plasma point was formed in the cathode plasma jet at a distance of ∼9.5 mm from the cathode. Quantitative analysis of the x-ray signals recorded using a pin diode with different filters and viewing different regions of the discharge, shows soft (∼keV photon energy) x-ray emission from the plasma point with a flux of ∼(3-5)x1010 photons/sr, and multi-keV x-ray emission from the Ti anode with Kα (∼4.51 keV) photon flux of ∼1010 photons/sr.