The weak effect of static, externally imposed, helical fields on fusion product confinement in the DIII-D tokamak

Stationary helical fields with toroidal mode numbers n = 1 and n = 3 are applied to beam heated DIII-D plasmas. Measurements of the 14 MeV neutron emission monitor the confinement of the 1 MeV tritium fusion product. To within ~ 15% uncertainty, static magnetic fields with vacuum amplitudes of dB/B ~ O(10-3) have no impact on fusion product confinement.