Miniature Plasma Focus Device as a Compact Hard X-Ray Source for Fast Radiography Applications

A table top ~0.2-kJ miniature plasma focus (PF) device "FMPF-1" (2.4 ??F, 27 ?? 2 nH, T/4 ~400 ns, 9-14 kV) has been successfully used as a compact and portable, pulsed hard X-ray (HXR) source for fast (< 32-ns exposure time) radiography applications using Hydrogen (H₂) as filling gas. The overall dimensions of the apparatus, which includes capacitor bank, sparkgap switch, and the focus chamber, are 0.2 m ?? 0.2 m ?? 0.5 m, and the system weighs about 25 kg. The time resolved information of HXR emission and their relative yield along the axial (0??) and radial (90??) directions are measured using a pair of cross-calibrated scintillator-photomultiplier detectors. The average pulse durations (full-width at half-maximum) of HXR pulse are measured to be 29 ?? 3 ns in axial direction and 18 ?? 2 ns in the radial direction. The average axial to radial HXR yield anisotropy is found to be 3.9 ?? 0.9 at the optimum pressure of 3.5 mbar. The experimental estimation of the effective average energy of the HXR emission, with high-Z (Pb) insert in stainless steel anode is found to be in the range of 60-80 keV. The potential of the miniature PF as compact radiographic source is illustrated by radiographic imaging, with submillimeter range (< 0.3 mm) spatial resolution, of different objects placed outside the chamber.