CALCULATIONS OF ALPHA-PARTICLE LOSS FOR REVERSED MAGNETIC SHEAR IN THE TOKAMAK FUSION TEST REACTOR

Hamiltonian coordinate, guiding center code calculations of the toroid al field ripple loss of alpha particles from a reversed shear plasma i n the Tokamak Fusion Test Reactor (TFTR) [Fusion Technol. 21, 1324 (19 92)] predict 40% total alpha losses and 20% ripple diffusion losses. T his is about double the loss rate of a comparable non-reversed magneti c shear plasma. High central q is found to increase alpha ripple losse s as well as first orbit losses of alphas in the reversed shear simula tions. Alpha ripple transport on TFTR affects ions within r/a = 0.5, n ot at the plasma edge. The entire plasma is above threshold for stocha stic ripple loss of alpha particles at birth energy in the reversed sh ear case simulated, so that all trapped 3.5 MeV alphas sue lost stocha stically or through prompt losses. (C) 1997 American Institute of Phys ics. [S1070-664X(97)04011-1].