August 14, 1997

FPN97-20 Fusion Program Notes

Sandia Ups X-Ray Record

Scientists in the Pulsed Power Program at Sandia National Laboratories, Albuquerque, who last year (see Fusion Power Associates June 1996 newsletter) set a world record of producing 85 terawatts and 500 kilojoules of x-rays, this year upped that record to 200 terawatts, 1.9 Megajoules (see Fusion Power Associates June 1997 newsletter). Recently they announced that they have successfully applied the technique to produce a 130 Ev black body radiation temperature in a vacuum hohlraum. Such hohlraums (cylindrical cases) can be used to provide a uniform source of energy to drive implosions in small capsules of fusion fuel. A radiation temperature of about 2-3 times that obtained on the Sandia facility is believed necessary to ignite such a fusion capsule in the laboratory.

The results are obtained by switching large amounts of stored electrical energy into a cylindrical array of fine tungsten wires, resulting in a burst of x-rays lasting several nanoseconds. In these latest experiments, the wire array is placed inside a vacuum hohlraum coated with 25 microns of gold. The size of the cylindrical hohlraum was 1 cm length and 2.5 cm diameter; the size of the 300-wire array in the hohlraum was 1 cm length and 2 cm diameter.

The Sandia results pave the way for accelerated testing of radiation effects on materials and electronics, weapons effects simulations and the study of the physics of inertial confinement fusion. Sandia has begun the conceptualization of a larger facility, dubbed X-1, that could be capable of reaching the hohlraum temperatures necessary for producing high gain in small fusion capsules in the laboratory.

For further information, contact Jeff Quintenz (jpquint@sandia.gov).

For more information, contact: Stephen O. Dean