Compact hard x-ray flash radiography device based on wire-shorted low-impedance rod pinch diode

Abstract

A rod pinch diode (RPD) is a feasible load configuration to generate a high-brightness, small-size hard x-ray radiation source. In this paper, the radiography performance of a wire-shorted low-impedance RPD on a compactly designed table-top driver (WRPD-1) is demonstrated for the first time. The driver consists of four high-power discharge branches connected in parallel, with each branch consisting of two metal-film capacitors and one multigap field-distortion switch in series. The four branches are triggered synchronously to generate a fast-rising current pulse: the inductance of the load section at the short circuit is ∼10 nH, and the short-circuit current amplitude is ∼325 kA at ±90 kV charging voltage, with a 10%–90% rise time of 110 ns. With a low-impedance RPD shorted by an 18-µm-diameter aluminum wire, a quasi-spherical x-ray focal spot with diameter <0.6 mm (width of the half-maximum grayscale) and a pulse duration of ∼25 ns (half-width of the radiation pulse) is obtained at ±70 kV charging voltage, and the imaging resolution excels 10 lp/mm under 1.56× magnification. According to the transmission–absorption x-ray spectrum estimation, the average emitted photon energy is ∼30 keV with a distinct peak in the 10–15 keV range that corresponds to the L-lines of tungsten, and the total energy of photons >10 keV reaches ∼1.16 J. The present results show that the device can serve well for the flash radiography diagnosis and potentially as an efficient light source for dynamic x-ray diffraction.