Main Ion Temperature and Rotation in the C-2W Field Reversed Configuration (FRC) Plasma

TAE Technologies' current experimental device, C-2W (also called "Norman"), produces an advanced beam-driven field reversed configuration (FRC) plasma. One of the newest diagnostics for the C-2W plasma is main ion CHarge Exchange Recombination Spectroscopy (mCHERS) to measure the main ion temperature and velocity. The diagnostic uses a 40kV/8Amp modulated diagnostic neutral beam to produce the charge exchange signal. Here we present the first observations and results from simultaneous measurements along five lines of sight. The radial profile of the measured main ion temperature shows a relatively flat distribution inside the separatrix. It is observed that increasing the bias voltage on the machine end electrodes results in higher main ion temperature. This measured trend builds on previous observations that the electrodes are key to both stability and performance of the C-2W FRC. The measured main ion temperature profile is compared with electron and impurity ion temperatures under various operating conditions. Main ion rotation measurements show a constant angular velocity inside the separatrix. Upgrades to the mCHERS diagnostic are currently underway to decrease measurement uncertainties and increase the number of channels, spectral resolution, and signal-to-noise ratio.