Confinement of fusion produced MeV ions in the DIII-D tokamak

The behaviour of tritons and 3 He ions produced in deuterium-deuterium fusion reactions is studied using the d(t, n)α and d( 3 He, p)α fusion reactions. Fusion produced MeV ions exhibit classical behaviour in high field (B T ≳ 1.0 T) discharges, including the new class of 'very high' confinement plasmas. However, anomalous behaviour is observed in discharges with strong sawtooth, fishbone or toroidicity induced Alfven eigenmode activity. For the high field discharges without strong MHD activity, the data imply an effective diffusion coefficient smaller than ≈ 0.1 m 2 /s, but in the presence of strong MHD activity the effective diffusion of the MeV ions exceeds 1 m 2 /s