Results of mid-plane and Jet region interferometry on the C-2W FRC experiment

TAE Technology’s C-2W experiment has been operational for over 18 months and has produced long-lived field-reversed configuration (FRC) plasmas. Plasmas are sustained by fixed and variable energy neutral beam injection (NBI)  sources. Multi-chord FIR interferometry of the FRC at the mid-plane of the confinement vessel is essential for operations, and interferometry in the mirror region of the confinement vessel quantifies the plasma outside the separatrix (last closed flux surface) which consists of: the plasma outflow through the X points (Jet plasma), the scrape off layer (SOL) plasma, and recycling from the inner and outer divertors. The magnetic field outside the FRC can be shaped and terminated on material limiters in a number of different ways. The plasma along open field lines terminating on the electrodes of the divertors can also be biased providing a wealth of variability for the boundary conditions of the FRC.  Interferometry measurements of the distribution of density within and external to the FRC for various C-2W operational programs are presented and the implications of the observed behavior on the performance of the plasma is discussed.