The effect of alpha particles on the stability of a bumpy torus reactor

Abstract

The macroscopic stability of an ignited ELMO Bumpy Torus (EBT) reactor is investigated by studying the effects of the alpha particles generated by the deuterium–tritium (D–T) fusion reaction on the background interchange mode, the interacting interchange mode, and the high‐frequency compressional Alfvén and coupled modes. A fluid description is used for the background plasma while a kinetic treatment is utilized for the hot‐electron species and the alpha particles. It is shown that the alphas tend to mildly destabilize the interacting interchange while stabilizing the background interchange because of their sizable Larmor radii. The destabilization is most pronounced when the beta of the alpha particles is highest, i.e., at birth, and recovery of stabilization takes place as these particles slow down toward thermalization. It is also shown that the alphas completely stabilize the high‐frequency modes, so that it can safely be concluded that fusion alphas present no detrimental effects on the stability of an EBT reactor that possesses an appropriate hot‐electron ring for macroscopic stability.