Four new low field side antennae grouped in pairs have been installed on TEXTOR. It is found that the interaction with the wall (density rise, impurity generation) is significantly reduced when operating each pair out of phase (E) as opposed to in phase (0). The beneficial effect in the n configuration is obtained without drop in plasma loading. This experimental property is shown, from theory, to be explained by the judicious choice of the geometrical configuration. A further improvement in the wall interaction is made possible by an appropriate choice of wall conditioning (wall carbonization with liner at 400'C or. above all, boronization). As a result record low values of PYsd/Ptota, were achieved during ICRH. The large reduction in wall interaction during ICRH allows routine long pulse (> 1 s) ICRH operation at the maximum power level available (g 2.5 MW).

The phenomenon of striation observed during pellet ablation in hot magnetized plasma is investigated experimentally injecting aluminum micro-pellets into MT-1M and TEXTOR-94 tokamak and W7-AS stellarator plasmas. Changes in pellet cloud shape and temporal fluctuations of total emitted line radiations are studied. Special attention is paid to the investigation of the dependence of fluctuation frequency on pellet velocity. The results show that the light fluctuation frequency is characterized by a characteristic time rather than by a characteristic length, and that the striation is caused by a phenomenon that occurs during the evolution of the ionized-pellet cloud. The compatibility of these experimental observations with different theories of striation is discussed.

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Abslract-Aluminium impurities were injected into the plasma of the MT-IM Tokamak. Line radiation of diRcrent aluminium ions (from AI I t o AI VIII) were identified. Two velocities were found for the toroidal dispersal: one is of the order ofU.1 cm fisc' for a few cmlimetres in the vicinity of the injection. the other is highcr than I cm for the whole Tokamak.fo!!owing. The ifijc&d ions gain !heir toroidal yp!ficity throcgh Co~!omb co![isiofis

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