EXCITATION AND PROPAGATION OF ELECTROMAGNETIC-WAVES IN NONUNIFORM DENSITY DUCTS

With the use of a full wave formulation, a study is made of radiation and propagation of electromagnetic waves in nonuniform cylindrical duc ts excited by given azimuthally symmetric sources. For an infinitely l ong duct, the eigenfunction set involving both localized and non-local ized waves is obtained for arbitrary values of driving frequency, exte rnal magnetic-field strength, plasma density, and its variation transv erse to the duct axis. Using this set, the radiation characteristics o f an annular current immersed in the duct are found for the whistler r ange. The subsequent propagation of excited waves is then analyzed in a duct whose parameters vary slowly along the external magnetic field. The applications of the results obtained are discussed.