Super-Reltrons and pulsed power issues

Abstract

A Super-Reltron High-Power Microwave tube uses post-acceleration of a well-bunched beam to generate microwave pulses with good efficiency. A steady electron beam is bunched by a two-cavity klystron oscillator mechanism in the modulating cavity, which consists of a three-cavity section of a side-coupled, standing-wave RF linac. A stable operating point is achieved when there is no net energy transfer from beam kinetic energy to cavity field energy, or vice versa. While the bunching mechanism is quite effective, the emerging electron bunches have a large energy spread. We therefore insert an accelerating gap immediately after the modulating cavity. This additional accelerating voltage reduces the relative kinetic energy spread, causing all the electrons in the bunches to move at nearly the same velocity. It also supplies more beam kinetic energy which can be usefully converted into microwave energy and improve efficiency. The manner in which this voltage is applied to the tube is the principal pulse power issue discussed by the author. (3 pages)