Diverted particle-flux studies in the IMS and Proto-Cleo stellarators

Diverted particle-fluxes have been measured under varying conditions in electron cyclotron resonance produced and heated plasmas in both the Interchangeable Module Stellarator (IMS) and the Proto-Cleo l=3, seven field period conventional stellarator. Flow patterns are observed to be dependent upon magnetic field strength in IMS, with abrupt changes observed as the central field strength passes through resonance with the microwaves. Electron injection into the IMS diverted-flux areas, using a strongly emissive filament, has been used to map connections between various diverted flux areas and to the scrape-off layer. Electron injection can also significantly alter observed divertor flows, in a fashion similar to previous results with divertor strike-plate biasing. Scoping studies of the diverted particle-flux pattern have been made in the Proto-Cleo Stellarator. Asymmetries are observed in the strength of the diverted flux along the path of the helical coil. These asymmetries are not strongly dependent upon moderate levels of applied external vertical magnetic fields. (author)