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INVESTIGATION OF MICROWAVE DUPLEXER SWITCHING MECHANISMS
ILLINOIS UNIV URBANA ELECTRICAL ENGINEERING RESEARCH LAB
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Evidence was found to indicate that longitudinal waves produced in various low pressure gases by a high power microwave pulse are under certain conditions pseudosonic waves. A glass tube filled with the low pressure gas is inserted into a S-band waveguide which carries the high intensity electromagnetic field. A plasma is created in the tube by the short high power level microwave pulse and the delayed propagation of the longitudinal waves is detected by observing the variation in the intensity of the visible light emitted by the decaying plasma. A much lower microwave power X-band frequency is applied to a small portion of the plasma column, having the effect of locally heating the already low temperature 3-500 K free electrons and, thereby, increasing the velocity of propagation of the pseudo sound wave in the heated region. This change in velocity is then measured as a change in the time of arrival of the longitudinal wave at a fixed detection point. This change in arrival time is shown to agree with that predicted by the theoretical behavior of pseudosonic waves. Author
APPROVED FOR PUBLIC RELEASE