Drift resonance in high density non-neutral plasmas

Abstract

Theoretical studies of the operation of crossed-field electron vacuum devices such as magnetrons and crossed-field amplifiers (CFA) have usually centered on their initial growth, taking this as an indication of their operating modes. In such an analysis one solves the equations for the density profile, the operating frequency, the growth rate, and other features of these devices. What one really obtains then are only the conditions for the device to turn on. The dominant interaction in this stage is a Rayleigh-type instability which initiates a quasilinear diffusion process whereby the electron density profile redistributes itself into a profile which will be in equilibrium with the ponderomotive-like forces produced by the growing rf fields. Eventually the rf fields will saturate and an operating device will settle into a stationary operating regime. This stage of a device’s operation is called the “saturation stage.” This latter stage involves a different set of physical interactions from the initiation stage. No longer is there a growth rate; rather the rf amplitudes have saturated and as a result, the ponderomotive-like forces have also vanished along with the quasilinear diffusion. In this saturation stage, we find that new rf modes appear. In fact, there are a total of five rf modes, two of which are the usual slow modes of the initiation stage, and three of which have fast oscillations in the vertical direction. One fast mode corresponds to a drift plasma oscillation while the other two fast modes are drift cyclotron modes. In this paper, we will describe how the drift plasma oscillation interacts and couples with the slow rf modes at the diocotron resonance.

Coherent Structures and Chaos Control in High-Power Microwave Devices

“…Once it is fully developed, it will advance the existing magnetron gain theories (Riyopoulos, 1998;Kaup, 2005, and references therein) which do not include them simultaneously. (Davies and Chen, 2006;Chen, 2003 and2004) Until our work (Davies and Chen, 2006, Bhatt and Chen, 2003, the influence of the anode corrugation on the equilibrium electron flow properties had not been discussed in the magnetron literature.…”