Plasma Distribution Measurement of a Miniature RF Plasma Thruster by Narrow-band Imaging

抄録

The measurement of exhaust plasma is useful for predicting thrust, and 2D distribution can estimate the thrust vector or plasma physics near the thruster exit region. However, measuring the spatial distribution in a narrow, millimeter-scale area of a miniature plasma thruster for miniature satellites is difficult. This study aims to obtain the qualitative spatial distribution of the electron and neutral-particle number densities of the miniature RF plasma thruster with a diameter of 3.4 mm using a simple optical system around the discharge-tube exit. An optical system capable of simultaneous magnified imaging at two wavelengths is developed, and the intensity of the 2D distribution of ArI of 420 nm and ArII of 488 nm emission lines is measured near the exit of the miniature RF plasma thruster. The local profile in the region of 10 mm × 10 mm near the thruster exit is obtained through Abel inversion, from the 2D distribution of the integrated values in the line-of-sight direction. The optically measured results qualitatively agree with the probe measurement at the downstream end of the measurement area.