A proposed 4 GHz, 60 kW transit-time oscillator operating at 18 kV beam voltage

A high-power transit-time oscillator operating at 4.0 GHz in the cylindrica l-cavity TM010 mode is proposed. Without requiring an externally applied ma gnetic field, the oscillator comprises a diode electron gun and a cylindric al cavity that are combined into a single unit that makes for a compact, li ghtweight device. The transit-time effect, which underlies the operation pr inciple of the oscillator, is examined through a small-signal analysis from which a relation embodying the cavity length, resonant frequency and catho de voltage is derived. Proper de voltages of 18 kV are applied to the diode gun which runs in the space-charge-limited regime and produces a 27A-curre nt hollow electron beam. Output power is extracted axially from the system by aperture coupling the cavity to an external waveguide where outgoing tra veling waves with 60 kW peak power are observed by means of 2.5D particle-i n-cell computer simulations.