ELECTRON-BEAM INTERACTION WITH A PLASMA-FILLED RIPPLED COAXIAL WAVE-GUIDE

The interaction of electron beam with a plasma-filled coaxial waveguid e with a rippled outer wall is studied. The dispersion equation descri bing the electron beam interaction with the slow-wave structure (SWS) is derived. The SWS eigenmodes are studied numerically as dependent on plasma density. The growth rates of the unstable modes and their depe ndences on plasma density, beam energy, and beam current are obtained. In the case of nonrelativistic electron beam, the maximum growth rate s of the instabilities in the plasma-filled SWS are shown to be much g reater than those in the vacuum SWS.