Radio frequency-driven energetic tritium ion tail measurements in the Tokamak Fusion Test Reactor using the pellet charge exchange diagnostic

Abstract

Charge exchange interactions of ions with the ablation cloud of an injected low-Z impurity pellet can be used to measure the energy spectrum and radial profile of confined fast ions in a fusion plasma. On the Tokamak Fusion Test Reactor we use this technique to directly measure energetic alphas from D–T reactions, tritons from D–D reactions, and radio frequency (rf)-driven minority tail ions (e.g., H, He3, T). We describe the status of the pellet charge exchange (PCX) diagnostic including a brief description of the measurement technique and discussion of operational experience. PCX measurements of the energy spectrum, radial density distribution, and heating deposition profile of rf-driven tritium ions during 2ΩT heating of L-mode plasmas are presented.