Fusion reaction spectra produced by anisotropic3He ions during ICRF

For 'beam-target' fusion reactions, collimated measurements of the energy spectrum of one of the reaction products can provide information on the degree of anisotropy of the reacting beam ions. Early measurements of the spectrum of 15 MeV protons produced by reactions between energetic 3 He ions and relatively cold deuterons during fast-wave minority heating in the PLT tokamak found an asymmetric, downward-shifted fusion spectrum. New spectral measurements with a thicker detector that collects the full proton energy indicate that the velocity distribution of fast 3 He ions is peaked perpendicular to the tokamak magnetic field.