Requirements and modelling of fast particle injection in RFX-mod tokamak plasmas

Abstract The planned upgrade of the RFX-mod device is a good opportunity to widen the operational space of the machine, in both RFP and tokamak configurations. Installation of a power neutral beam injector is also envisaged and a NB system compatible with RFX-mod, formerly installed in TPE-RX, is already available on site. In this work, the METIS simulator is used to study the feasibility of TPE-RX injector integration in RFX-mod circular tokamak plasmas. METIS code allows the simulation of a full tokamak discharge, with the addition of the neutral beam injection (NBI) which, in METIS, is described by a decay equation applied in a simplified geometry and an analytical solution of the Fokker–Planck equation. In this work, RFX-mod scenarios with NBI have been studied, with careful attention to the beam absorption and plasma response to the additional heating.