Electrical discharge in the Teflon cavity of a coaxial pulsed plasma thruster

In this work, we analyze the physical processes of a pulsed discharge in a dielectric (Teflon) cavity, This type of discharge is generated in a coaxia l pulsed plasma thruster (PPT) having a central Teflon cavity to produce a high-pressure cloud of ablation products during the discharge pulse, The pr imary intended role of this model is to provide upstream boundary condition s for particle simulation codes used to study the exhaust plume, The main f eatures of the electrical discharge in the dielectric cavity include Joule heating of the plasma, heat transfer to the dielectric, decomposition of th e dielectric followed by partial ionization, and acceleration of the plasma up to the sound speed at the cavity exit. We consider a diffuse type of di scharge assuming that all plasma parameters are uniform in the cavity, The system of equations is based on the plasma energy balance, thermal conducti vity, dielectric ablation, and mass balance, It is found that most of the e nergy of the plasma column is carried off by particle convection to the die lectric and by radiation. It is found that during the pulse, the electron d ensity peaks at about 10(24) m(-3) and decreases to 10(21) m(-3) toward the end of the pulse, whereas the electron temperature peaks at about 2.2 eV a nd decays to 1.5 eV, Teflon surface temperature peaks at about 650 K, Predi cted plasma temperature and ablated mass are found to be in agreement with available experimental data.