Modelling of 'advanced tokamak' scenarios with radiofrequency heating and current drive for Tore Supra

A possibility of 'advanced tokamak' operation based on RF heating and curre nt drive is studied using 1-D transport modelling for long pulse tokamaks s uch as Tore Supra, A current drive with lower. hybrid and fast magnetosonic waves and strong electron heating with ion cyclotron waves are applied in tills scenario. The self-consistent evolution of the energy, particles and current densities is simulated, starting from an ohmic plasma and arriving at a non-inductive steady state equilibrium. An estimation of the RF. power required for the setting up of this equilibrium characterized by an improv ed confinement due to the building up of particle and energy internal trans port barriers in the reversed magnetic shear configuration is presented. Th e maximum bootstrap, current fraction attained in this scenario is about 50 %. A limit on the bootstrap current fraction in plasmas with an L mode edge and improved core confinement produced due to the stabilizing effect of a low or negative magnetic shear is found. The conventional operational techn iques with fixed plasma current or controlled plasma Aux and non-inductive current are compared with the operation with the current profile control al gorithm, and the advantages: of current profile control are shown. The resu lts presented are relevant tu present tokamaks operating with RF heating an d current drive and possibly to future tokamak projects aimed at advanced o peration.