Experimental investigations of tungsten X-pinches using the QiangGuang-1 facility

Abstract

In order to obtain a single brighter point X-ray source, tungsten X-pinch experiments were carried out on the QiangGuang-1 facility. The equilibrium radius of the bright spots was estimated based on the energy balance equation. X-pinch load test covered wire diameters from 25 to 100 μm, wire number from 2 to 48, and the load linear mass from 0.18 to 6.9 mg/cm. The load peak current was 1.0–1.4 MA and the rise time for 10%–90% was 60–70 ns. From the experiments, the matched load for “QiangGuang-1” facility was the 30 or 32 wire-25 μm X pinch with the load linear mass of 2.8–3.0 mg/cm, which can produce a single nanosecond X-ray pulse around current peak with a certain probability. A typical keV X-ray radiation had a pulse width of 1 ns, the radiation power from the bright spot being 35 GW, the radiation yield being 40 J, and the spot size being about 30 μm. Multiple bright spots and multiple X-ray bursts at the crossing were usually observed in the experiments. Multiple X-ray bursts were probably caused by secondary pinches or partial pinches, and multiple bright spots were caused by long wavelength perturbations or localized short wavelength perturbations along the “min Z-pinch” axis. Compared with hundreds of kilo-ampere devices, mega-ampere facilities produced greater X-ray radiation, but further improvements are needed to produce a single X-ray burst steadily.