Fast-ion Characteristics in Colliding FRCs with Neutral Beam Injection

Tri Alpha Energy's C-2 device [1] aims to explore confinement properties of colliding Field-Reversed Configuration (FRC) plasmas, augmented with neutral beam injection. Naturally, it is desirable to understand the general characteristics of the resulting fast- ion population. For this purpose, several 16 channel silicone-based Neutral Particle Bolometers (NPB) have been designed and installed on the C-2 device, measuring charge-exchanged fast-neutrals originating from the fast-ion population. We present results illustrating the effects on fast-ions from wall recycling and from the $\mathrm{n}=2$ rotation instability. In addition we find good agreement between NPB measurements and Monte Carlo simulations. The NPB diagnostics are a spatially resolved complement to the energy resolved Neutral Particle Analyzers installed on the C-2 device. \\[4pt] [1] M. W. Binderbauer {\it et al}, Phys. Rev. Lett., {\bf 105}, 045003 (2010)