Characterizing Neutron Emission from the Fusion Z-Pinch Experiment (FuZE)

The sheared-flow stabilized (SFS) Z-pinch fusion design is being developed as a potential source of clean energy. A suite of diagnostics measure neutron yield, spatiotemporal neutron emission, and deuteron beam energy via neutron energy isotropy. The Portable Adaptable Neutron Diagnostic for ARPA-E (PANDA) that has been deployed at Zap Energy is composed of two types of neutron detectors: LaBr₃+Y activation detectors and EJ230 plastic scintillators coupled with PMTs (S/PMT). The cross calibrated LaBr₃+Y activation detectors measure the total neutron yield, while the S/PMT detectors provide a time resolved signal that can be used for measuring spatiotemporal neutron emission or deuteron beam energy depending on the setup. The experimental setup and data analysis have been developed and optimized for these measurements on the FuZE SFS Z pinch to characterize the temporal and spatial neutron emission. The spatial extent of the neutron emission is calculated as a function of time for each discharge in multiple datasets as the machine parameters of voltage, pressure, and gas timing are changed. Magnetic field probes along the z axis of the device are used to calculate the axial current as a function of position. Optical Thomson scattering measurements are performed on the same datasets to measure the electron temperature at two axial locations along the Z-pinch plasma in the FuZE device. Comparisons between diagnostics give a more complete picture of the Z-pinch plasma conditions.