Considerations for Alpha Particle Diagnostics

Abstract

Several diagnostic methods are possible for measuring the spatial and energy distributions of alpha particles in three different contexts: the fast confined alpha particles in the fusion plasma, the thermalized alphas (the He "ash") and the alpha particles escaping from the plasma. Many phenomena, such as single and double charge exchange from neutral beams to the alpha particles, damping of lower hybrid waves, emission at ion cyclotron harmonics, γ-ray emission from nuclear reactions with the alpha particles, and small-angle laser scattering as well as escaping alphas, are involved in the different proposals for determining the phase space distribution of the fusion-produced alpha particles in burning D-T plasmas. The necessary developmental effort is greatly influenced by the high neutron and x-ray backgrounds.