Measurements of Fusion Yield on the Centrifugal Mirror Fusion Experiment

Abstract: The Centrifugal Mirror Fusion Experiment (CMFX) at the University of Maryland, College Park is a rotating mirror device that utilizes a central cathode to generate a radial electric field which induces a strongly sheared azimuthal $E\times B$ flow to improve plasma confinement and stability. The fusion yield of CMFX plasmas is assessed by diagnosis of neutron emission for the first time. The total neutron yield is measured with two xylene (EJ-301) and deuterated-xylene (EJ-301D) liquid scintillator detectors absolutely calibrated with an in silico method. A larger xylene scintillator was cross-calibrated and used to measure the time dynamics of the fusion rate under various experimental conditions. A permanently installed $^3$He gas tube detector was independently calibrated with a Cf-252 neutron source to make total yield measurements and provide an independent validation of the scintillator calibration. An interpretive modeling framework was developed using the 0D code MCTrans++ (Schwartz et al 2024 JPP) to infer undiagnosed plasma parameters such as density, temperature, and confinement time. A peak neutron emission rate of 8.4$\times 10^{6}$ $\pm$ 7.0$\times 10^{5}$ was measured (neglecting modeling uncertainties), with an inferred triple product of 1.9~$\times~10^{17}$ $\mathrm{m^{-3}}$ keV s from 0D modeling.