Design of a new electromagnetic diagnostic for RFX

A new set of electromagnetic probes has been designed for the RFX modified toroidal assembly. Typology and layout of the probes have been revised based on the analysis carried out in previous experiments, and taking into account the foreseen scenarios of operation. A large number of probes are required to correctly identify the complex spatial structure of the plasma column. An accurate calibration and a careful probe mounting is required. Probes will be installed inside the stabilising shell, which will be placed very close to the vessel. Very little space is available. A two axes pick-up probe has been developed: probe materials and construction techniques have been optimised in order to minimise coupling between the two coils and the dependence of the measurement on the temperature. Extensive tests have been carried out on probe prototypes to characterise their electrical and thermal behaviour. In the paper, the design of the new set of probes is presented, and the results of the tests performed on prototypes are reported.