LAUSR

Abstract The steady-state operation of the fusion neutron source (FNS) will require the injection of high-energy atomic beams for plasma heating and current drive. In the DEMO-FNS project, the six injectors are planned to be used that will provide the additional heating power of up to 30 MW, the energy of atoms being 500 keV. The concept of plasma beam heating and current generation system is proposed. The injector developed in detail for the ITER project can be used as a prototype for the DEMO-FNS injector. In this injector, the atomic current is the same, and the beam energy and power are two times higher. Variants of the gas isotopic composition in NBI and the role of the NBI gas supply system in the facility fuel cycle are described. The problem of the efficient beam transport in a neutral beam injection (NBI) system requires the 3D modeling and multiparametric optimization of all elements of the beam path. The optimization is aimed at minimizing the beam losses during its transport and reducing the thermal loads onto the injector components to the acceptable values that make possible the efficient cooling. The techniques for defining the optimal geometry and the results of studies of different operation modes of the NBI system are presented. The main factors affecting the transport efficiency, including the inaccuracies in the beam adjustment and the presence of the external magnetic fields, are considered and their restrictions are formulated. The optimal self-consistent configuration of the injector and the initial ion beam was chosen, and the operating ranges of the parameters were determined. The total losses, the time evolution of the beam power profile and the detailed thermal load distributions were calculated and can be used for the engineering design of the NBI system.