Basic theoretical formulations of plasma microwave electronics - Part I: Afluid model analysis of electron beam-wave interactions

This two-part paper presents the first complete. generalized basic theoreti cal formulation for electron beam-wave interactions in a plasma-filled (cor rugated or smooth-walled) waveguide immersed in a finite magnetic field. Th e general interaction and dispersion equations of the longitudinal and tran sverse interactions in both smooth and corrugated magnetized plasma-filled waveguides (HPWs) are formulated. Our approach differs from that of previou s investigators in that we begin by first deriving the dispersion relation of an MPW and then using the resulting electromagnetic fields, which embody the plasma effects, as the basis field vectors, We then investigate the un derlying interactions with a superimposed electron-beam in a variety of;mic rowave device configurations. For example, we examine plasma Cherenkov radi ation, the plasma-filled travelling-wave-tube/backward-wave-oscillator (TWT /BWO), the plasma-filled electron cyclotron resonance maser (ECRM), and oth er beam-wale interactions including those involving ion-channels. Some poss ible new interactions in a magnetized plasma-filled waveguide (MPW) are pro posed, A detailed discussion and analysis of the important physical role of the plasma background are given, Many interesting features of beam-wave in teractions in an MPW are pointed out, three of them being most essential, O ne is that transverse interactions are always accompanied by longitudinal i nteractions, The second is that the magnetized plasma itself is strongly in volved in the interaction mechanisms via an additional component of the hel d, The third interesting feature is that the plasma-filled ECRM prefers to operate at high cyclotron harmonics. The first part of this two-part paper presents formulations using a fluid model for both the plasma and the beam. It also includes a detailed treatment of the physical effects of the ion c hannel that is formed in the plasma by an intense electron beam. Part II ex tends the analyzes by retaining a fluid treatment for the plasma-fill but s ubstituting a kinetic theory treatment for the electron beam, This kinetic theory model should be used when the velocity spread of the beam's electron s must be taken into account. The theory presented in both parts of this pa per is based upon the "given field" approach that has been widely used succ essfully in science and technology, in particular in microwave electronics, In both parts of the paper, sample numerical calculations are also present ed in order to illustrate the physics.