Discharge startup problems in an ITER tokamak reactor

The initial stage of current rise in a tokamak reactor along the lines of ITER is studied up until the formation of a separatrix configuration in the magnetic surfaces. Self-consistent calculations of the heat and particle transport have been carried out in the main and near-wall plasmas, and the thermal loads of the first wall of the chamber in the first stage have been determined in the approximation in which the first wall coincides exactly with a toroidal surface. The effect of rippling in the toroidal magnetic field on the magnitude of the maximum thermal load on the first wall is estimated. Alternative scenarios for discharge startup are constructed with magnetic configurations that are asymmetric in the vertical direction. These permit the separatrix to develop for smaller currents in the plasma, and also reduce the thermal loads on the divertor plates. 10 refs., 9 figs., 3 tabs.