Temporal evolution of electron beam transport in PASOTRON microwave sources

The plasma-assisted slow-wave oscillator (PASOTRON) is a high-power microwave source, in which the transport of an intense electron beam through an interaction region is based on the focusing effect of a beam generated plasma channel (Bennett pinch). A simple theory is developed which describes the self-consistent nonstationary processes of the plasma formation due to impact ionization of an axially inhomogeneous gas by the beam and the beam focusing effect of the plasma. The theory is illustrated by examples showing the temporal evolution of the beam transport in the process of plasma creation in PASOTRONs.