A new approach to wide-band, high gain, crossed-field amplification

For many years there has been interest in magnetron-type traveling wave tubes to achieve high power level amplification bcause of the more efficient interaction possible between electrons and r.f. waves in crossed electric and magnetic fields. This paper describes a new approach to obtaining crossed-field amplification. Work along these lines has resulted in a new device, called the Circlotron amplifier, which is a one-port, re-entrant, magnetron-type structure obtaining its high gain by means of internal regenerative feedback, its wide bandwidth by means of heavy load damping, and its separation between output and input signals through use of a ferrite circulator. Tubes have been designed and built with various degrees of loading. The heavily loaded tubes behave as regenerative amplifiers while the higher Q tubes behave as forced oscillators. Experimental results will be presented showing agreement between theory and experiment. At the present time gains greater than 20 db have been obtained at X-band frequency over a 5% bandwidth at 1 to 10 kw peak power output levels. Lower gains have been obtained over a 13% bandwidth. Operation has been at high efficiency (30% to 60%).