Measurement of the Transition to Oscillation in the Recirculating Planar Crossed-Field Amplifier

The Crossed-Field Amplifier (CFA) is a compact device that can efficiently amplify high power microwaves (HPM) and is relatively broadband. However, not much is known about the ultimate gain and power limitations of CFAs and the transition point at which the CFA will oscillate. This research examines the transition from amplifier to oscillator of the Recirculating Planar Crossed-Field Amplifier (RPCFA). The RPCFA was designed to operate between 2.75-3.05 GHz and has been shown to produce over 5 MW of power with an input of about 600 kW
¹
. Initially, the RPCFA is stable in the absence of a RF-drive signal, but with sufficient feedback, the structure was shown to oscillate
²