Investigation of Energetic ICRF Minority Protons on Alcator C-Mod

Energetic minority protons with $\sim $100keV effective temperature are routinely created in C-Mod plasmas with the application of ICRF. A new multi-channel Compact Neutral Particle Analyzer is used to make measurements of these distributions via an active charge-exchange (CX) technique. Using a detailed model that accounts for beam, halo, and impurity CX, core proton temperatures of $\sim $30-100keV are observed for lower density (n$_{e0}\sim $1-1.5x10$^{20}$/m$^{3})$ C-Mod plasmas using only $\sim $0.5MW of ICRF power. The model found that these fast minority protons are peaked spatially away from r/a=0, even for an on-axis resonance. Additionally, noticeable phase-space anisotropy is seen as expected for ICRF heating. The measured effective temperatures scale approximately with the Stix parameter. Preliminary comparisons with results from the AORSA/CQL3D Full-wave/Fokker-Planck code using a new synthetic diagnostic show good agreement and demonstrate that these complex codes are required to simulate C-Mod's energetic minority populations with accuracy.