UC Irvine

Fast ion research is necessary to understand confinement of high energy particles in fusion devices like DIII-D. Measuring the fast ion distribution is necessary to understand how well it is confined. The fast ion D-alpha (FIDA) diagnostic and neutral particle analyzer (NPA) are two diagnostics that measure part of the distribution. Upgrades to the FIDA diagnostic are necessary to resolve scattering issues from the unshifted D-alpha emission that contaminates other parts of the measured spectra. Effective filter performance is possible using the reflection of a narrow bandpass filter. The imaging neutral particle analyzer (INPA) was developed on DIII-D to provide greater spatial and energy resolution compared to traditional NPAs. Measured images are validated using simulations. Robust passive signals are also observed and found to come from fast ion populations traversing the edge. Fast ions can also interact with plasma waves or modes to transfer energy which can lead to losses. The energetic particle-induced geodesic acoustic mode (EGAM) is one plasma mode that is excited by fast ions. Various phenomena associated with EGAMs are characterized to assess the impact it has on fast ions.