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

• Published in: IEEE transactions on plasma science Vol. 38; no. 4; pp. 652 - 657
• Main Authors: Verma, Rishi, Rawat, R S, Lee, Paul, Krishnan, Mahadevan, Springham, Stuart V, Tan, T L
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.04.2010; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Anisotropy; Chambers; Detectors; Devices; electrical discharges; electron beam; Emission; Errors; Filling; Focusing; hard X-ray (HXR); Hydrogen; Miniature; miniature plasma focus (PF); Miniaturization; Plasma; Plasma applications; Plasma devices; Plasma focus; Plasma sources; Plasma x-ray sources; Pulse measurements; Radiography; scintillation detector; Sensors; Switches; Syntax; X-rays
• ISSN: 0093-3813; 1939-9375
• DOI: 10.1109/TPS.2010.2041558

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 (H 2 ) 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.