Compact high current generator for x-ray radiography

We report here a design of the portable high current generator, which can be used for a row of experiments and applications, including, but not limited to, X pinch, plasma focus, vacuum spark, etc. The X generator consists of the capacitor bank, multigap spark switch, load chamber, and built-in high voltage triggering generator. The capacitor bank consists of 12 General Atomics 35404 type capacitors ( 20 nF , 25 nH , 0.2 Ω , 100 kV ). It stores ∼ 0.8 kJ at 80 kV charging voltage. Each three capacitors are commuted to a load by the multigap spark switch, which is able to commute by eight parallel channels. Switches operate in ambient air at atmospheric pressure. At 76 kV charging voltage the generator provides ∼ 260 kA with 120 ns rise time and 5 nH inductive load and ∼ 220 kA with 145 ns rise time and 10 nH . Delay of output pulse relative to high voltage triggering pulse is ∼ 65 ns with 5 ns jitter. The dimensions of the generator are 1240 × 1240 × 225 mm 3 and the weight is ∼ 250 kg , and only one high voltage power supply is required as additional equipment for the generator. The generator with a pumping system is placed on area about 0.5 m 2 . Operation and handling are very simple, because no oil nor purified gases are required for the generator. The X generator has been successfully employed for experiments on the Ni X pinch load. X-ray pulse duration (full width at half maximum above 1 keV ) was about 5 ns . Radiation yield W r ⩾ 500 mJ was observed in the 1.2 – 1.5 KeV range and W r ⩾ 20 mJ in the 3 – 5 keV energy range, which is comparable to results, obtained on the nanosecond accelerators. Clearly resolved images of 6 μ m wire indicate micron level size of hot spot. These results demonstrate possibility of this generator for application for x-ray backlighting.