Observation of discharge arc properties in pulsed plasma thruster

As one kind of electric space propulsion systems, pulsed plasma thrusters transform electrical energy into kinetic energy of an exhaust medium by means of a pulsed discharge. Due to the short discharge time, the nature of the discharge remained unraveled for long time. In recent years, indications from experimental work pointed to a strong similarity with vacuum arc thrusters and triggered vacuum gaps, including the presence of an arc. This study applies optical methods including high-speed camera observation and emission spectroscopy in a first attempt to describe the discharge arc in a pulsed plasma thruster. Results include the position and broadness of the arc as a function of time and voltage as well as a description of the species based on the spectral data.