3D fluid model analysis on the generation of negative hydrogen ions for negative ion source of NBI

摘要

A radio-frequency（RF） inductively coupled negative hydrogen ion source（NHIS） has been adopted in the China Fusion Engineering Test Reactor（CFETR） to generate negative hydrogen ions. By incorporating the level-lumping method into a three-dimensional fluid model, the volume production and transportation of H- in the NHIS, which consists of a cylindrical driver region and a rectangular expansion chamber, are investigated self-consistently at a large input power（40 k W） and different pressures（0.3–2.0 Pa）. The results indicate that with the increase of pressure, the H- density at the bottom of the expansion region first increases and then decreases.In addition, the effect of the magnetic filter is examined. It is noteworthy that a significant increase in the H- density is observed when the magnetic filter is introduced. As the permanent magnets move towards the driver region, the H- density decreases monotonically and the asymmetry is enhanced. This study contributes to the understanding of H-distribution under various conditions and facilitates the optimization of volume production of negative hydrogen ions in the NHIS.