Plasma Diagnostics in Supersonic Flow Containing Cesium and Potassium

Electron density, collision frequency and electron extinction rates have been computed from microwave absorption measurements on the exhaust plumes of solid propellant rocket motors burning CsNO3:Al and KNO3:Al The plasma was generated by burning the fuel at a chamber pressure above 100 psi, and expanding the gases through an orifice to an ambient pressure of 1 Torr. The plume consists of both gases and solid particles which modify the aerodynamic flow. High speed movies together with grid wires in the flow field were used to define the plume. Microwaves operating at frequencies up to 70 gc were used for measuring the plasma properties.