Noninterference Velocity Measurements in a Supersonic Seeded Plasma Using Tracers Produced by a Spark Discharge and a Focused Pulsed Laser

摘要

Experimental results are presented from a program conducted to develop a noninterference method for obtaining the velocity of a supersonic, high enthalpy plasma seeded with an alkali metal. The technique used was the time-of-flight measurement of a tracer spark produced in the plasma by an electric spark discharge (two pointed electrodes) and by a focused pulse laser. The tracer spark was photographed with a streak and framing camera or an image-converter camera at preselected delay times to obtain the time-of-flight velocity measurements. The experimental work was accomplished in air and nitrogen plasmas, at a static pressure of about 1 atm and at total enthalpies up to 2700 Btu/lb. Velocities were measured up to 2600 m/sec. The techniques used are described, and the problems and results are discussed. (Author)