Experiments with the nanosecond plasma-flow-switch output device on the S-300 pulsed power generator

Abstract

Summary form given only, as follows. Results of experiments carried out at the Kurchatov Institute are within the framework of the S-300 scientific program. This program is aimed to the sharpening of pulsed power and subsequent conversion of stored electromagnetic energy into soft X-ray radiation. We investigated special output devices similar to plasma flow switches but operating in the nanosecond range of pulse duration. The plasmas between the inner and outer cylinders were accelerated by means of the current pulse of a generator. The current amplitude was as high as 2.5 - 4 MA. Thin (1.5 μm) aluminum - coated mylar films were used to create an accelerated plasma source. With both streak and framing regimes of ICT, the homogeneity of the mylar film breakdown was studied, as well as the velocity of the plasma along the inner electrode; velocities up to 108 cm/s were measured. When the accelerated plasma reached the gap on the inner cylinder, the current and magnetic flux switched onto the internal cavity of a Hohlraum-type output device. Single wire or multi-wire arrays with diameter ∼2 mm (16 tungsten wires of 6 μm diameter each) were used as a load placed inside the hohlraum. Switching was indicated by recording the soft X-ray pulse from the cavity and shunt measurements of the current on the load. A fast regime of switching the current ∼2.5 MA with the front width ∼2.5 ns onto the load was achieved. Soft X-ray radiation was recorded by means of two vacuum diodes with a nickel cathode and specially selected filters. The temperature inside the cavity as estimated from the ratio of diode signals was close to 50 eV.