Identification of RFX plasma shape from the electromagnetic probe signals

The paper presents the application and the first results of a plasma shape identification code used in the RFX experiment. This code has been specifically developed for machines provided with a stabilizing shell and with magnetic probes placed outside the vacuum vessel. In RFX, as in all the present-generation RFP machines, no steady-state magnetic configuration is reached, being the eddy currents in the vessel and in the stabilizing shell not negligible during the whole pulse duration. The new code, known as PLACID (Plasma Contour Identification) makes use of the information from the electromagnetic probes to estimate, by means of a filament current model, the currents in the vacuum vessel and in the stabilizing shell. In this way the solution to the magnetostatic problem of the determination of the magnetic flux surfaces outside the plasma is provided.