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

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 in-creases 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.