Optical measurements of unsteady phenomena on coaxial pulsed plasma thrusters

At Gifu University, to understand unsteady operation phenomena including plasma generation and exhaust processes on a coaxial pulsed plasma thruster (PPT), the luminescence behavior has been studied. In this study, spatial velocity distributions were compared with the results of electrostatic measurement and high-speed photography, and the applicability of a photosensor system to the plume measurements in the region slightly downstream of the nozzle was confirmed. Using the results of the measurements using the photosensor system, the dependence of the impulse bit of the PPT on the cavity geometry was investigated. In addition, direct observations of the ablation process in the cavity of a propellant with slits were carried out. The duration of late-time ablation measured for the propellant with slits is longer than that for the propellant without slits. The results of the observations reveal that the direct observation method is effective for investigating late-time ablation phenomena.