Electrodynamic pulse shortening mechanism due to a novel beam/cavity interaction

Summary form only given, as follows. Beam/Cavity interactions are fundamental the understanding and production of high power microwaves (HPM), especially in klystron-type devices. Relativistic klystron oscillators and amplifiers (RKO/A) using intense relativistic electron beams (IREB) are an active area of research and development to produce HPM at the Gigawatt level. We report on a novel beam/cavity interaction, unique to these intense space charge beams, wherein the electromagnetic field energy is reflected back into the cavity if the beam density is sufficiently high. This effectively raises the Q of the cavity, and potentially destroys coupled cavity modes. This novel mechanism can explain pulse shortening in the Air Force Research Laboratory's RKO and features of RKA research performed at the Naval Research Laboratory in the late 1980's. Results include simulations in the time and frequency domain, as well as an analytic scaling law for this phenomenon. These results are compared with experimental data.