Experimental research on a diode packaged with a compact and lightweight permanent magnet

Abstract

In order to make the high-power microwave sources packaged with a permanent magnet more compact and miniaturized, we design a novel compact and lightweight permanent magnet package based on a C-band coaxial transit time oscillator. Before conducting the microwave generation experiment, research on the emission and transmission is carried out. In the beam transmission experiment, when the compact and lightweight permanent magnet is applied, the transmission efficiency in the diode is only 68.1%, while a phenomenon of side emission of electron beams is observed. When a solenoid is used, no side emission occurs. We theoretically analyze this experimental phenomenon and conclude that the radial magnetic field generated by the permanent magnet aggravates the side emission on the surface of a cathode holder. To solve this problem, a novel diode with a gradient cathode holder is proposed. In the beam transmission experiment using the compact and lightweight permanent magnet, this diode can suppress the side emission of electron beams, and the transmission efficiency in the diode is increased to 80.7%. The potential of the diode proved to work efficiently with this permanent magnet package, laying the foundation for the experimental research of microwave generation with this permanent magnet.