The Project of Osaka Institute of Technology Electric-Rocket-Engine onboard Small Space Ship (PROITERES) was started at Osaka Institute of Technology in 2007. After successfully launching the 1st PROITERES satellite, the 2nd PROITERES satellite with electrothermal Pulsed Plasma Thrusters (PPTs) has been developed since 2010. The main mission is powered flight with longer distance, i.e. changing more than 10km in altitude on near-earth orbits by high power PPTs. In this research, a 30W-class PPT system was developed by experimental and numerical simulation. In the present paper, we examine the interior physical phenomena and the performance characteristics by numerical simulation when changing cavity length. As a result, calculated performances agreed with experimental ones, and the cavity lengths between 10mm and 50mm with a stored energy of 31.59J achieved a maximum total impulse of 67.1Ns.
