Design of embedded electrostatic sensors for the RFX-mod2 device

The RFX-mod experiment is currently undergoing a challenging upgrade of the machineassembly. One of the main purposes of RFX-mod2, the upgraded device, is the achievement of betterperformances by decreasing the tearing modes amplitude in Reversed-Field Pinch (RFP) configu-ration thanks to a higher plasma-shell proximity. Moreover, most of the innovations characterizingthe device and its diagnostics are conceived with the aim of operating as both RFP and tokamak.These different configurations are taken into account in the electrostatic sensors design and layout.RFX-mod2 will be equipped with poloidal and toroidal arrays of electrostatic probes, measuringplasma density and temperature, plasma potential, particle and energy fluxes and floating potentialfluctuations. Two toroidal arrays of 72 probes each (one on the high field side and one on the lowfield side), along with four poloidal arrays of 28 elements, are foreseen. Such a large amount ofsensors is due to the requirement of a better characterization of the numerous instabilities observedin the RFP plasma edge, with the possibility to study the plasma shape in different tokamak config-urations (circular, single null, double null). Three different kinds of Langmuir probe configurationswill be installed: single probes, 5-pin balanced triple probes and ball-pen probes. The conceptualdesign of the sensors takes inspiration from the model successfully installed on RFX-mod, thatallows the removal of tiles in case of damage, by means of a remote handlining manipulator.