Convective amplification of drift waves and thermal fluctuation levels in a stable plasma

The possibility that convective amplification of drift waves gives rise to significant thermal fluctuation levels in a stable tokamak plasma is investigated. A test particle formulation yields a differential dispersion equation, which is amenable to numerical solution. It is found that, for realistic tokamak parameters, the calculated thermal fluctuation levels are far below those measured experimentally. Convective amplifications are localized and relatively small. The largest calculated fluctuation levels are due to an enhancement of the thermal source strength for frequencies near the eigenfrequencies of weakly damped normal modes.