Tokamak reactor with a self-sustaining current

The current in a tokamak reactor can be sustained by fusion ..cap alpha.. particles in a noninductive manner, by virtue of the asymmetry of the region from which fast ions are lost. The conditions under which the ..cap alpha.. particles can sustain the current in the plasma are determined. Two types of fusion reactors are proposed, with structural differences which stem from different impurity levels near the magnetic axis.