Steady State ECRH Operation at the W7-X Stellarator

Abstract

The Steady state operation can be defined for various characteristic physical time scales. Usually one speaks of steady state plasmas when the discharges are stationary for several energy confinement times. The next longer time constant is the L/R time for the development of the toroidal plasma current. Ultimately, the gas equilibrium must also be achieved. W7-X is ideal for creating stationary conditions for the different plasma parameters. In the operation phase OP1.2, the experimental operation was neither limited by the confining magnetic field nor by the pulse length of the ECRH. Only the maximum tolerable temperature of the uncooled in-vessel components and the test divertor unit (TDU) limited the total input energy. Therefore this paper presents steady state operation different plasma parameters with different time scales.