Energy confinement of the high energy tail electrons during lower hybrid current drive experiments on the Alcator C tokamak

Abstract The distribution function of the high energy electron tail generated during lower hybrid current drive experiments at a density of n e =3×10 19 m −3 in the Alcator C tokamak has been determined. By performing a convolution integral with the collision operator, the power flow into the bulk plasma was calculated. With the assistance of code modeling, the energy confinement time of the fast electrons, and its dependence upon energy, was determined. It is shown that the energy confinement of tail electrons is comparable with that of the bulk particles.