Electron Temperature and Density Diagnostics of a High-Voltage Cross-Field Device

A small-scale cross-field device (called the Orbitron) is being explored as a compact fusion reactor. In the initial prototype of this cylindrically symmetric device, deuterium ions are confined through orbits around a 100kV cathode with co-rotating electrons confined by a weak axially magnetic field of 0.05 T. To benchmark PIC simulations, an investigation of pure-electron plasmas confined in the Orbitron is currently underway. These plasmas are low-density n_e<10¹⁰ cm^-3, highly energetic E ~ 20keV, and non-thermal, which makes analysis of classical diagnostics challenging. Here we discuss preliminary measurements of these pure-electron plasmas via Bremsstrahlung and optical emission spectroscopy with a gas backfill, and our plans for future electron temperature and density diagnostics.