Improvements in power flow and load geometry increase x-ray power by 25% on PBFA Z
Since the PBFA Z shot at Sandia National Laboratories on November 21, 1996 that produced 1.8 MJ and 160
TW in soft x rays from a z-pinch implosion, incremental improvements have been made to the load and the
power flow. The current rise time was decreased by 6 ns and the azimuthal symmetry of the wire array loads
was further enhanced. On the 38th radiation shot (Shot 51) on March 26 we attained a new record of 200 TW
in peak x-ray power for the facility. The radiation pulse width was nominally 6 ns FWHM and the energy in soft
x rays was 1.9 MJ. As for the November 21 shot, the load consisted of 240 tungsten wires, each 7.5 microns in
diameter, configured in a cylindrical array at a diameter of 4 cm and a length of 2 cm. Shot 51 occurred
following an experimental series to study radiated energy and power scaling for wire arrays ranging from 2 to 4
cm in diameter. On April 1 we began a series of shots with the imploding wire array inside a vacuum hohlraum.
A 3-cm-diameter array was selected as the optimum for these experiments, whose purpose is to provide a
radiation source for science-based stockpile stewardship experiments. Improvement in power flow is especially
important for smaller diameter arrays, which--because of their higher inductance--couple less energy to x rays.
In the next week or two, we will study the performance of z-pinch loads that have their inductance lowered by
reducing the gap between the return current can and the outer edge of the wire array from 5 mm to the 2.5 mm
used on Saturn. We expect to produce hohlraum radiation temperatures of > 120 eV with an optimized load
configuration.
Other Reports on High Energy Density and Inertial Confinement Fusion
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