ELECTROMAGNETIC PROPERTIES OF CORRUGATED AND SMOOTH WAVE-GUIDES FILLED WITH RADIALLY INHOMOGENEOUS-PLASMA

Creation and diagnosis of plasma in microwave devices remains one of t he primary challenges of plasma microwave electronics. In the present work we deal with 1) diagnostic techniques for characterization of rad ially nonuniform plasma columns suitable for use in high-power microwa ve sources and 2) the effects of such plasmas on the electromagnetic p roperties of finite length, spatially periodic slow wave structures, E xperimental studies were performed both for a strong and a weak guidin g magnetic field. Using a combination of a microwave resonator (X-band ) and a Langmuir probe, both the plasma peak density and its transvers e profile were measured in situ (prior to beam propagation), The frequ ency upshifts of the TM(01n) modes in an open corrugated cavity were m easured as a function of the background plasma density, The dispersion diagrams were reconstructed, for the first time, up to a peak plasma density of 10(12) cm(-3). Frequency upshifts and ''flattening'' of the dispersion curves were observed for both strong and weak guiding magn etic fields, For plasma density above 5 x 10(11) cm(-3) the frequency upshifts are less than anticipated by theory.