Excitation of global modes in TEXTOR and comparison with theory

The excitation of fast-wave global eigenmodes is investigated both experimentally for TEXTOR and theoretically using a slab coupling mode. A brief comparison with a cylindrical model shows that in the TEXTOR situation no essential geometrical effect is left out by the slab code. The resonant behaviour associated with eigenmodes is studied for several signals: the resistance and inductance of the antennae the r.f. magnetic and electric field components picked up by probes at the plasma edge, and the power coupled to a fast-wave antenna used as a receiver. It is shown that all the major features of these signals linked to the existence of eigenmodes can be explained using the theoretical models.