Empirical Determination of Radiation Energetics of Inertial Confinement Fusion Relevant Wire-Array Z-Pinches

Abstract

Summary form only given. The radiation power and energy produced by 20 mm diameter, 300-wire tungsten arrays of various masses was studied on the 20 MA, 100 ns Z pulsed power facility. On some tests, 1-mm diameter Al rods were inserted on the axis of the array both to limit the convergence and to reduce possible sources of magnetic kinetic energy. Empirical estimates of the kinetic energy of the implosion were made using x-ray pinhole camera and streak images, transmission-grating- spectrometers, and 6151 eV radiography. These were compared to the energy radiated before and during the main power pulse, which is the portion relevant for inertial confinement fusion applications, as well as the total energy radiated from the Z-pinch. It is clear that the total energy radiated by these wire arrays requires energy input above and beyond the kinetic energy of the implosion, as noted elsewhere for Al arrays, The energy radiated during the main power pulse (generally about half of the total radiated energy) is close to the estimated implosion kinetic energy for the heavy arrays studied here, but for the lightest arrays there may be some discrepancies. Specifically, the size of the X-ray emitting regions measured with three independent diagnostic methods appears too large to be consistent with the high convergence ratios required to explain the main pulse radiation energy. Supporting analyses of a mass-density profile obtained via radiography and circuit model energetics are ongoing at the time of this abstract, as well as an error analysis to understand whether we can conclusively support the statement that a non-kinetic source of energy is required to explain the main radiation pulse.