Selective mode filtering for gyrotron traveling-wave tube systems

Abstract

In this paper, a method to filter the parasitic modes for gyrotron traveling-wave tube (gyro-TWT) system is proposed. The difference of surface current between the operating TE₀₁ mode and the parasitic modes is analyzed to achieve the mode discrimination. Based on the analysis, a slot array with high mode-selectivity is introduced, and a Ka-band oversized waveguide mode filter is designed to attenuate the parasitic modes. A prototype is fabricated and measured for validation purpose. The measurement of S-parameter demonstrates that parasitic modes can be effectively suppressed by the mode filter, while the TE₀₁ mode suffers little attenuation after propagating through the proposed device. The high-power capacity of the mode filter is verified by a high-power test based on a gyro-TWT. The proposed mode filter features high performance in purifying TE₀₁ mode as well as a high-power capacity, which makes it suitable for gyro-TWT systems.

KEYWORDS:

• Gyro-TWT
• high-power
• mode filtering
• slot radiation
• oversized waveguide

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Natural Science Foundation of China [Grant Number 61921002].