EXPERIMENTS WITH PLASMAS PRODUCED BY POTASSIUM-SEEDED CYANOGEN OXYGEN FLAMES FOR STUDY OF RADIO TRANSMISSION AT SIMULATED REENTRY VEHICLE PLASMA CONDITIONS

摘要

A method for the chemical production of an ionized gas stream for application to radio transmission studies is described. Involved is the combustion of gaseous cyanogen and oxygen with the addition of vaporized potassium in some cases to further increase the ionization. Experiments are described in which a 3-inch-diameter subsonic free jet at atmospheric pressure is used, and the results are presented.nThe plasma obtained by using this method is sufficient to simulate plasma conditions expected for reentering hypersonic vehicles. The unseeded plasma stream temperature is indicated to be about 4,200° K, with the degree of ionization indicated to be that expected from thermal equilibrium considerations.nMeasurements of radio-signal loss due to the unseeded flame plasma are presented for microwaves of 8 to 20 kmc transmitted through the stream and for a dipole transmitting model of 219.5 mc immersed in the stream. Favorable comparison of these results with the simple plane-wave signal-attenuation theory was obtained. In the case of a 9.4-kmc microwave signal of 30-kw peak power, the preliminary indication is that the plasma characteristics were not changed due to this strong signal.