Simulations of alpha particle ripple loss from the International Thermonuclear Experimental Reactor

Abstract

Calculations of collisional stochastic ripple loss of alpha particles from the new 20 toroidal field (TF) coil International Thermonuclear Experimental Reactor (ITER) [Plasma Physics and Controlled Nuclear Fusion Research (International Atomic Energy Agency, Vienna, 1991), Vol. 3, p. 239] predict small alpha ripple losses, less than 0.4%, close to the loss calculated for the full current operation of the earlier 24 TF coil design. An analytic fit is obtained to the ITER ripple data field demonstrating the nonlinear height dependence of the ripple minimum for D-shaped ripple contours. In contrast to alpha loss simulations for the Tokamak Fusion Test Reactor (TFTR) [Fusion Technol. 21, 1324 (1992)], a simple Goldston, White, and Boozer stochastic loss criterion [Phys. Rev. Lett. 47, 647 (1981)] ripple loss model is found to require an increased renormalization of the stochastic threshold δs/δGWB≳1. Effects of collisions, sawtooth broadening, and reversal of the grad-B drift direction are included in the particle following simulations.