The engineering design of quarter size negative beam source for the comprehensive research facility for fusion technology

A high-power radio frequency (RF) beam source is a key component for Negative Neutral Beam Injector (NNBI) in ASIPP. According to the technical route planning of CRAFT-NNBI beam source project, ASIPP started thedevelopment of quarter-size RF negative source and corresponding test facility. The inner diameter of the faradayshield (FS) of RF driver is 240 mm, the outer diameter of the accelerator is 1 m, with three-layer grids extractionsystem, which comprises the plasma grid (PG), extraction grid (EG) and ground grid (GG). The size of PG is512 mm × 396 mm × 9 mm, with two rows of 16 × 6 apertures made of pure molybdenum. The structure designof RF negative beam source and the manufacturing process of key components are presented, with emphasis onthe manufacturing process of FS as well as grids. Furthermore, the fluid-thermal-structural analysis of PG, themechanical analysis and material bonding strength test of the main insulation structure of beam source, as wellas the preliminary layout of the latest test facility are presented.