Single langmuir probe measurement in the exit plasma of an arcjet thruster

The parameters of ejected plasma in the range of 1.25~15cm to the exit of 1kW class arcjet with nitrogen as propellant were measured with a single langmuir probe. The pressure in the vacuum chamber was 3~5 Pa. The changes of electron temperature(0.4~0.8eV) and number density(ranging from 1.2 × 10 ¹⁷ to 1.25 × 10 ¹⁸m ^-3) along the axial and radial direction were obtained. The results showed that both the electron temperature and number density of ejected plasma with nitrogen as propellant were higher than those with N ₂-H ₂ as propellant, while the divergence angle was smaller.