An alternative residual ion dump for the ITER neutral beam system

An alternative concept of the residual ion dump for the ITER NBI system is presented. The incentive is to avoid the inherent risk of the in-line electrostatic ion removal concept, which is presently foreseen in the NBI design: beam-blocking by enhanced reionization losses and potential amplification of electron currents by electrostatic acceleration. It is proposed to use instead a conventional magnetic ion removal system with remote ion dumps. This method of removing the residual ions has been proven in almost all injection systems world-wide over the last two decades. First calculations show that the maximum power load can be kept below 15 MW/m2, sufficiently low to use conventional dump plate designs.