UHF noise generator, utilizing the diocotron effect

We have previously reported that a large rotational electron current circles the inside of the anode in the cold cathode Penning discharge and that this current is unstable as a consequence of the diocotron effect. We have observed that by splitting the anode, it is possible to couple effectively to the space charge bunches which result from the instability. The output obtained in this way, consists of short bursts of radiation. The radiation frequency centers around the rotation frequency of the electrons, but varies substantially during each burst. We have made use of this random radiation pattern and have developed a high power noise generator. Our present prototypes deliver noise powers in excess of 20 watts at an efficiency of up to 25% in the UHF region of the spectrum. The noise spectrum is voltage tuneable, and the band width, which is electronically rather than circuit limited, is approximately 10%.