α-particle transport induced by Alfvén eigenmodes in the Helias reactor

Abstract

It is shown that in the Helias reactor [1], depending on the ratio γL/γd with γL(d) the linear growth (damping) rate of the Alfvén eigenmode (AE), there are three regimes of the transport of α-particles resonant with AEs. (i) For 1<γL/γd<<10 the transport is determined solely by the pitch-angle scattering of αs trapped by an AE. In this regime τα>>τs, with τα(s) the α-particle confinement (slowing down) time. (ii) For γL/γd∼10 the dominant transport mechanism is the adiabatic convection of the slowing-down αs trapped by an AE, with particle `life time' in resonance with AE limited by pitch-angle scattering. In this regime τα∼τs. (iii) For γL/γd>> 10 the transport become stochastic with τα<<τs.