A low-impedance transit-time oscillator without foils

Abstract

A low-impedance transit-time oscillator (LITTO) without foils is proposed and studied by simulation. By using a coaxial structure, the space-charge limiting current can be improved significantly, thus allowing higher input and output powers. With no foils to erode, the only factor limiting the repetition rate is the ability to maintain an adequate vacuum. By contrast with conventional transit-time oscillators, the proposed LITTO has the advantages of low diode impedance, rapid saturation time, and a possibility of repetitive operation. As indicated in PIC simulation, the average microwave output power is over 5.0 GW at the main frequency of 1.6 GHz, with an input electron beam of 36.0 kA current and 600 kV voltage, and an external magnetic field of 0.45 Tesla.