Experimental Investigation of a Relativistic Magnetron With Reducing Coaxial Section and Tilted Tuners

A compact, frequency-tunable, and efficient relativistic magnetron (RM) featuring a reducing coaxial section (RCS) and tilted tuners was developed and experimentally tested. The study validates numerical predictions through experiments, focusing on sustained oscillations, power efficiency, and frequency tuning. Four cathode configurations were tested. The solid cathode with reduced diameter yielding the best results: up to 34% efficiency, 450-MW average output power, and 1.55-GW peak power at 430 kV. A tuning bandwidth of 16% was achieved between 1.8 and 2.12 GHz. Plasma effects were investigated via improved particle-in-cell (PIC) simulations using a dispersive Drude model, identifying plasma as the main source of observed RF instabilities and pulse shortening.