Deuterium-tritium simulations of the enhanced reversed shear mode in the Tokamak Fusion Test Reactor

The potential performance, in deuterium-tritium plasmas, of a new enhanced confinement regime with reversed magnetic shear [enhanced reversed shear (ERS) mode] is assessed. The equilibrium conditions for an ERS mode plasma are estimated by solving the plasma transport equations using the thermal and particle diffusivities measured in a short duration ERS mode discharge in the Tokamak Fusion Test Reactor [F. M. Levinton et al., Phys. Rev. Lett. 75, 4417 (1995)], The plasma performance depends strongly on Z(eff) and neutral beam penetration to the care. The steady-state projections typically have a central electron density of similar to 2.5 x 10(20) m(-3) and nearly equal central electron and ion temperatures of similar to 10 keV. In time-dependent simulations the peak fusion power, similar to 25 MW, is twice the steady-state level. Peak performance occurs during the density rise when the central ion temperature is close to the optimal value of similar to 15 keV. The simulated pressure profiles can be stable to ideal magnetohydrodynamic instabilities with toroidal mode number n = 1,2,3,4 and infinity for beta(norm) up to 2.5; the simulations have beta(norm) less than or equal to 2.1. The enhanced reversed shear mode may thus provide an opportunity to conduct alpha physics experiments in conditions similar to those proposed for advanced tokamak reactors. (C) 1997 American Institute of Physics.