The Inverse Z-Pinch as a Physics Test Bed, and a Possible Target Plasma for Magnetized Target Fusion (MTF).

From an overall fusion system perspective, there remains an untested and interesting possibility of compressing a magnetized target plasma with beta greater than unity by a magnetically driven imploding liner, or other target pusher driver. This approach, known as Magnetized Target Fusion (MTF), operates in an intermediate density regime and time scale between magnetic and inertial fusion, which are separated by twelve orders of magnitude. Even if magnetized plasma transport is Bohm-like, fusion gain in the MTF parameter space appears accessible with existing drivers, which means MTF does not require a major financial investment in driver technology. The physics of plasma confinement by material walls, and the thermal transport of magnetized high-beta plasma in the MTF regime, has received relatively little study theoretically, computationally, or experimentally. This paper describes a proposed experiment to test wall confinement in a regime of plasma parameters relevant to MTF. The geometry being considered is an inverse pinch designed to heat plasma to 100-eV temperatures. By using a current crowbar, the plasma formed in the pinch can be held against an outer wall (the return conductor) and the rate of cooling can be measured and compared with predictions from theory and numerical models. The well-benchmarked two-dimensional radiation-MHD code MHRDR, is being used to guide the design activity. The existing 2-terawatt Zebra generator at the Nevada Terawatt Facility is the power supply under consideration. Results from the code show adequate heating, formation of a quasi-static magnetic equilibrium, and a near-classical cooling rate to a room temperature boundary, even in the presence of substantial plasma convection. [ABSTRACT FROM AUTHOR]