Theoretical modeling of crossed-field electron vacuum devices

The modeling of crossed-field electron vacuum devices, such as magnetrons a nd crossed-field amplifiers with a dc background mode and an rf pump mode i s discussed. The dominant interaction in these devices is the wave-particle interaction (diocotron). This interaction drives the classical Brillouin f low nonlinearly unstable through a Rayleigh-type instability in a shear flo w. This linear instability triggers the nonlinear instability, which is a s econd-order nonlinear diffusion process. This diffusion process is driven b y the density gradient at the edge of the sheath, which causes the electron density to evolve into a new density profile, one which will be in equilib rium with the nonlinear diffusion process. The general physics of the vario us processes contained in this model is discussed, including a possible exp lanation for the ultra-low noise phenomena. (C) 2001 American Institute of Physics.