Impact of Neutral Beam Parameters on Current Drive and Neutron Yield in the Compact Tokamak

Abstract

To study the effect of the beam–plasma system geometry on current drive and generation of neutrons in plasma, an efficient model was used that combines the statistical description of the injected beam with the analytical methods for calculating particle trajectories. The calculation results were consistent with the classical models of interaction of neutral beams with plasma. The model presented is simple and high-performance that makes it possible to trace up to 10¹² fast ions in plasma and quickly optimize the facility parameters with allowance for the plasma and beam geometry. It is shown that the dimensions and inner angular structure of the atomic beam considerably affect the process of fast ions capture in plasma and overall efficiency of neutral beam injection (NBI), including the current drive efficiency and generation rate of fusion neutrons during the interaction of fast ions with plasma ions. An example is presented of optimizing the NBI parameters for the FNS-C fusion neutron source based on the spherical tokamak. The current drive efficiency (NBI‑driven current) and neutron yield of the beam–plasma fusion reactions were chosen as target criteria for the system optimization.