Effects of the grid breakdowns on the acceleration Grid Power supply of the ITER NBI

The acceleration grids of the ITER Neutral Beam Injector (NBI) are likely to be subjected to frequent breakdowns. As a consequence, large voltage oscillations arise on the power supply terminals, which could stress the system and may propagate to the power supply. This paper deals with the analyses carried out to assess the impact of such voltage oscillations on the Acceleration Grid Power Supply (AGPS) of the NBI. A detailed high-frequency model of the power supply is setup and simulations are run, with the aim of estimating the voltage and current stresses at the primary side of the AGPS. The results are analyzed and discussed, giving inputs for the design and testing of the equipments.