Alpha particle generation and confinement in D-3He scenarios in JT-60SA

Future fusion reactors will rely on a significant fraction of self-heating by fusion born alpha particles coming from the DT plasma fuel mix. Understanding alpha particle generation and confinement is therefore critical and, in anticipation of ITER, should be subject to thorough research. Experimentally, however, no current large device can operate with DT fuel and therefore alternative schemes for alpha particle generation come into play. Since DT operation is not foreseen in the scientific exploitation of JT-60SA, a fusion scheme relying on ³He seeding and highly energetic 500 keV neutral beam is proposed similarly to what has been used in other devices such as JET although in there the original ∼100 keV scale beam ions were further accelerated using RF waves. In this work we investigate the generation and confinement of alpha particles stemming from this ³He + NBI scheme, taking the forthcoming OP2 and future hybrid scenarios as reference plasmas. We will show that owing to the high-energy N-NBI system on JT-60SA, significantly higher values of alpha/neutron production rates can be achieved when considering similarly scoped experiments on JET while using significantly lower ³He concentrations. Loss power and particle rates will also be discussed and optimised alpha birth rates shown for specific variants performed on the hybrid scenario where plasma density, position and temperature were varied at constant plasma current and magnetic field.