LANGMUIR AND HEAT-FLUX PROBES FOR RFX

A movable limiter made of graphite and instrumented with an array of Langmuir and heat flux probes has been developed for the reversed field pinch experiment RFX. The limiter is mushroom shaped and designed to be exposed to the edge plasma for a discharge duration almost-equal-to 250 ms. The distribution of the probes on the limiter surface allows simultaneous collection, in a single discharge, of edge parameters at different angles and radial positions. A bellows drive system with three degrees of freedom allows the instrumented limiter to be rotated and translated to investigate the spatial structure of the edge plasma. Cables and feedthroughs have been designed for 1-kV voltage and 5-A current. The power supply provides an output voltage +/- 100 V and a maximum current 4 A. Specific software has been developed for the automatic analysis of the Langmuir probes data.