Phaedrus-T tokamak probe measurements

Phaedrus-T is an ISX class tokamak [B≤1T, R congruent 0.9 m, a congruent 0.25 m, IP∼100 kA, ne(0)congruent 2x1019/m3, and Te(0)∼500 eV], which began operation in 1989. Measurements of the Phaedrus-T edge plasma parameters have been made with triple probes, swept Langmuir probes, swept emissive probes, self-emissive probes, reciprocating probes, capacitive probes and shadowed probes of various sizes and materials. ICRF current drive studies are the focus of the Phaedrus-T program; and, consequently, most Phaedrus-T probe measurements have been of ICRF/edge plasma interactions. Data showed strong ICRF modifications of the edge plasma when an antenna with a conventional stainless steel Faraday Shield was used; greatly reduced ICRF/edge coupling when 1/4 inch boron nitride side limiters were placed on the Faraday Shield; and no significant change in the ICRF/edge coupling when the Faraday Shield was later removed (even though there was a significant reduction in plasma impurities)