Two-stream cyclotron radiative instabilities due to the marginally mirror-trapped fraction of fusion alphas in tokamaks

摘要

It is shown here that the marginally mirror-trapped fraction of newly born fusion alpha particles in deuterium–tritium (DT) reaction-dominated tokamak plasmas can induce a two-stream cyclotron radiative instability for fast Alfvén waves propagating near the harmonics of the alpha-particle cyclotron frequency [omega]c[alpha]. This can explain both the experimentally observed temporal behaviour and spatially localized origin of the fusion-product ion cyclotron emission (ICE) in TFTR at frequencies [omega][approximate]m[omega]c[alpha].