Experiments on a Recirculating Planar Crossed-Field Amplifier

The Recirculating Planar Crossed-Field Amplifier (RPCFA) has demonstrated amplification in excess of 10 dB of a ~30 kW RF signal, with 15% bandwidth. The RPCFA is the amplifying adaptation of the Recirculating Planar Magnetron (RPM) also developed at the University of Michigan. Ansys HFSS and the particle-in-cell code MAGIC were used to design a prototype. The prototype RPCFA was constructed and demonstrated transmission characteristics similar to those predicted by simulation. Sustained amplification for pulses 100's of nanoseconds in length have been observed with peak amplification as high as 16dB and greater than 1 MW of output power. The RPCFA is shown to be unsaturated at the 10's of kW RF drive at which it has been tested, suggesting higher input drive power may lead to even greater output power. The range of amplifiable frequencies implied by the transmission band is verified experimentally. The lower limit for RF drive power that can be amplified is found to be approximately 100 W. Sources of irreproducibility of microwave gain are being investigated. Injection of higher drive power up to 1 MW is planned.