Proposed plasma edge diagnostics for jet

A proposal has been prepared for three facilities for diagnosing the plasma surface interactions and the plasma edge parameters in JET. The principal system proposed will be for plasma edge diagnostics. A carriage driven by linear motors and containing up to five probes will be transferable into the torus from a surface analysis station. After exposure to a discharge the probes can be returned to the analysis station and analysed before the next discharge. The second system will be for short-term specimens. It will consist of a magazine of samples which can be exposed in the torus for one or more well-defined discharges. These samples will be introduced and removed from the torus via a “vacuum suitcase”. The third system, termed “long-term” samples, consists simply of regions on the inner wall of the torus where samples can be fixed at different toroidal and poloidal locations. These samples will be removed in stages during the lifetime of the machine and examined to see the long-term integrated effects on surface damage, mechanical properties, and hydrogen isotope implantation.