A porous flow control element for pulsed plasma thrusters

The examination of a permeable flow element for PPT propellant feeding is presented. The intention is to identify the control parameters for a self-controlled propellant flow through the element. As the element, a permeable WHIPOX (R)-fibre ceramic is used, feeding water propellant. It is found that the propellant transport is both driven by pressure gradients within the structure and evaporation into the discharge region. For functional testing, a mass flow rate of 340 mu g/s is chosen, the PPT being operated against 5 Pa ambient pressure and showing reproducible ignition behaviour. Finally, the system is compared to a PTFE propellant system by spectrometric and photographic analysis of the plasma and by comparison of the electrodes indicating less erosion for water operation.