THE HAGIS SELF-CONSISTENT NONLINEAR WAVE-PARTICLE INTERACTION-MODEL

The problem of modelling the self-consistent interaction of an energet ic particle ensemble with a wave spectrum specific to magnetically con fined plasmas in a torus is discussed. Particle motion in a magnetic f ield coordinate system, whose surfaces are perturbed by a spectrum of finite amplitude magnetohydrodynamical (MHD) waves, is described using a Hamiltonian formulation. Employing the Sf method enables the simula tion particles to only represent the change in the total particle dist ribution function and consequently possesses significant computational advantages over standard techniques. Changes to the particle distribu tion function subsequently affect the wave spectrum through wave-parti cle interactions. The model is validated using large aspect-ratio asym ptotic limits as well as through a comparison with other numerical wor k. A consideration of the Kinetic Toroidal Alfven Eigenmode instabilit y driven by fusion born alpha-particles in a D-T JET plasma illustrate s a use of the code and demonstrates nonlinear saturation of the insta bility, together with the resultant redistribution of particles both i n energy and across the plasma cross section. (C) 1998 Elsevier Scienc e B.V.