Study on influence of hydrogen partial pressure on hall thruster plasma focusing characteristics in ground vacuum system

The effects of the hydrogen component pressure on the beam focusing characteristic and oscillating characteristic of the thrusters are studied and analyzed based on the methods of spectrum diagnosis and probe diagnosis. The analysis indicates that with the increasing of the hydrogen partial pressure in the vacuum tank, the strength of the characteristic spectral line of hydrogen in the channel increased. The relative radiation intensity of H_I =652.6 nm with the condition of p_H =0.04Pa has been raised 8~9 times as compared with the condition of p_H = 0Pa. The backflow of the hydrogen component towards the inside of the channel affects the ionization and ion acceleration progresses, and thus causing the deviation of the beam focusing characteristic and increased low frequency oscillation. In the condition of p_H =0.04Pa, the plume divergence half-angle is 41.5°, which increases by 24.5° compared with the condition of p_H =0Pa.