Studies of the low-energy neutral behavior using the low-energy neutral particle analyzer on EAST

Abstract

• The neutral energy spectrums with an energy range of 20–3000 eV was measured by the low energy neutral particle analyzer (LENPA). • In the LENPA detection range, more than 85 % of neutral particles are in the energy range of 20–1000 eV. • The integrated neutral flux in the energy range of 20–1000 eV increases with line-averaged density in ohmic discharges due to the increased charge exchange reaction rates in a higher density plasma. • Due to the deeper penetration depth by SMBI fueling, the neutral particles are generated closer to the core plasma and have higher energy. • The neutral flux increases with heating power in all energy range. The neutral energy spectrums with an energy range of 20–3000 eV was measured by the low energy neutral particle analyzer (LENPA) in the 2021 EAST summer campaign. The proportion of the neutral particles below 1000 eV measured by LENPA is more than 85 %. In the ohmic discharges, the integrated neutral flux increases with increasing the line-averaged density. However, the neural particles with higher energy (1000–3000 eV) are insensitive to the line-averaged density. In addition, the neutral flux in the energy range of 20–1000 eV of the discharges with supersonic molecular beam injection (SMBI) was lower than those without SMBI, which was different from neutrals in the range of 1000–3000 eV. The neutral flux increases with higher auxiliary heating power in all energy range. Compared to the ohmic discharges, the mean energy of neutral particles in auxiliary heated discharges is increased significantly.