ADVANCED EMITTERS FOR NEXT-GENERATION RF AMPLIFIERS

Next generation rf amplifiers, in particular the inductive output ampl ifiers (IOAs), will require electron sources characterized by high cur rent density, high brightness, low emittance, and the ability to be em ission gated. The strong interaction between the beam and the resonant or synchronous electromagnetic field may enable compact, highly effic ient, and moderate gain X-band power booster amplifiers. An analysis o f amplifier demands on generic emitter candidates is provided. Of the emitter candidates available, two (namely, field emitter arrays and wi de-band-gap semiconductors) are amenable to an analysis predicated on a simple model of field emission from hyperbolas and ellipsoids. The s imple model is used to investigate two problems of critical concern: f or field emitter arrays (FEAs), we will investigate the conditions und er which important space charge effects exist, and from the model pred ict optimum FEA performance characteristics for rf IOAs; for wide-band -gap materials, the simple model identifies parameters which limit the maximum electron transport across a metal-semiconductor interface, th ereby limiting current flow.