The Deflagration - Detonation Transition in Gas-Fed Pulsed Plasma Accelerators

A hydromagnetic Rankine-Hugoniot model for propellant acceleration in gas-fed pulsed plasma thrusters is presented and verified against available experimental data. Building on early work by Cheng et al [Nuclear Fusion 10, pp. 305-317, 1970], the snowplow mode is compared to a detonation process and it is shown here that a competing “second” mode, which was observed independently in gas-fed pulsed plasma thrusters by Ziemer et al [Ph.D. Dissertation, Princeton University, 2001], can be explained as a plasma deflagration process. Based on the presented model, a single equation is derived for these two modes, which gives the exhaust velocity of gas-fed pulsed plasma thrusters as a function of controllable parameters. It is found that the developed model is consistent with experimentally measured exhaust velocities for varying mass bit sizes.