The Effects of Preheating of a Fine Tungsten Wire and the Polarity of a High-Voltage Electrode on the Energy Characteristics of an Electrically Exploded Wire in Vacuum

Results obtained from experimental and numerical studies of tungsten wires electrical explosion in vacuum are presented. The experiments were performed both with and without preheating of the wires, using positive or negative polarity of a high-voltage electrode. Preheating is shown to increase energy deposition in the wire core due to a longer resistive heating stage. The effect was observed both in single wire and wire array experiments. The evolution of the phase state of the wire material during explosion was examined by means of one-dimensional numerical simulation using a semiempirical wide-range equation of state describing the properties of tungsten with allowance made for melting and vaporization.Comment: 9 pages, 9 Postscript figure

Soft x-ray measurements of z

This article reports the experimental characterization of a z-pinch driven-vacuum hohlraum. The authors have measured soft x-ray fluxes of 5 x 10{sup 12} W/cm{sup 2} radiating from the walls of hohlraums which are 2.4--2.5 cm in diameter by 1 cm tall. The x-ray source used to drive these hohlraums was a z-pinch consisting of a 300 wire tungsten array driven by a 2 MA, 100 ns current pulse. In this hohlraum geometry, the z-pinch x-ray source can produce energies in excess of 800 kJ and powers in excess of 100 TW to drive these hohlraums. The x-rays released in these hohlraums represent greater than a factor of 25 in energy and more than a factor of three in x-ray power over previous laboratory-driven hohlraums

Plasma Liner with an Intermediate Heavy Shell and Thermal Pressure Drive

One of the challenging problems of Magnetized Target Fusion is development of the ways of transporting energy to the target situated at a large-enough distance from the energy source: the distance should be such as to prevent damage to the permanent parts of the source. Several schemes have been considered in the past, including the use of particle beams coupled with the inverse diode, mechanical projectiles in combination with magneto-compressional generators, and the plasma liner. In this paper, a possible modification of the original concept of the plasma liner (Y.C.F. Thio, C.E. Knapp, R.C. Kirkpatrick, R.E. Siemon, P.J. Turchi. J. Fusion Energy, 20, 1, 2001) is described. The modification consists in creating a thin, higher density shell made of a high-Z plasma and accelerating it onto an MTF target by a thermal pressure of a hydrogen plasma with the temperature {approx}10 eV. We discuss constraints on the parameters of this system and evaluate convergence ratio that can be expected