Generating Fusion Neutron Sources from MHD Models of a Shear-Flow Stabilized Z-Pinch

The Z-pinch has been considered for use in controlled thermonuclear fusion for almost a century, but instabilities have made it difficult to achieve proper plasma confinement. Using a uniform axial plasma flow over the pinch plasma under certain flow conditions, some stability occurs and leads to longer plasma confinement times. This technique, referred to as shear-flow stabilization, has been investigated in several laboratory experiments, and the most successful of them has been the Fusion Z-Pinch Experiment (FuZE). FuZE has demonstrated absolute neutron yields of ~10⁵ n/pulse with emission durations of ~8 μs, and now, there are active pursuits with new machines to explore the scaling toward a fusion reactor. However, absolute neutron yield could be a misleading metric if neutrons emitted from beam-target fusion or other radiological events are included in the count. For this reason, great thought must be given to neutronics instrumentation and measurement techniques, and this effort largely relies on simple models of the neutron emitting volume from the plasma. Therefore, a study was performed to generate neutron emissivity profiles from the plasma in FuZE using 2-D axisymmetric, resistive MHD models. With these more complex source descriptions, Monte Carlo neutron transport calculations were performed and verified with past measurements, and new neutronics instrumentation/methodologies are suggested.