Development of Periodic Cusped Magnet Focusing System for a miniaturized W-band Sheet-Beam Traveling-Wave Tube

Abstract

In recent years, the development of miniaturized W-band (75-110 GHz) traveling-wave tubes (TWTs) with a staggered double grating slow-wave structure (SDG SWS) and a high-aspect-ratio sheet electron beam (SEB) has attracted particular interest for the development of the submillimeter band, particularly for next-generation high-speed wireless communication systems. Such a device will be able to provide output power up to 100 W and a gain of over 25 dB at frequencies near 100 GHz. To ensure beam focusing over the long distances required for beam-wave interaction in TWTs, a promising approach is the use of periodic cusped magnet (PCM) focusing systems. These systems consist of a sequence of small permanent magnets with alternating magnetization directions, separated by iron pole pieces. This approach allows both device miniaturization and stable beam transport in the SWS tunnel without diocotron instability at distances over several cm.
This work presents a 3D simulation of the 500×150-μm² 0.1-A 14.6-kV SEB transport in the beam tunnel of a miniature W-band TWT with a SDG SWS, focusing with nonuniform periodic magnetic fields. Optimal magnetic field values were obtained for a stable EB focusing in the beam tunnel. Based on the obtained results, the optimized PCM system design was developed that provide a magnetic field on axis of up to 0.22 T and ensures SEB transport over distances of up to 10 cm.
This work was supported by the Russian Science Foundation (grant #25-72-00050).

Speaker

Alina D. Murlaeva
Saratov Branch Kotelnikov Institute of Radioengineering and Electronics of RAS
Russia

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