Demonstration of a High Power, Wideband 220-GHz Traveling Wave Amplifier Fabricated by UV-LIGA

TLDR

The study discusses fabrication errors and target tolerances, and shows how this microfabrication technique could enable vacuum electron devices up to 1–2 THz with high‑current‑density electron guns. The authors present the first vacuum electronic traveling wave amplifier that uses UV photolithography and electroforming to fabricate its interaction circuit. The amplifier’s all‑copper interaction circuit was built in two layers by embedding a UV‑transparent polymer monofilament in photoresist to form the beam tunnel before electroforming. The device delivers over 60 W of output power at 214.5 GHz from a 12.1 kV, 118 mA beam and achieves an instantaneous bandwidth of about 15 GHz in the G‑band small‑signal regime.

Abstract

We present the first vacuum electronic traveling wave amplifier to incorporate an interaction circuit fabricated by ultraviolet (UV) photolithography and electroforming, demonstrating over 60 W of output power at 214.5 GHz from a 12.1 kV, 118 mA electron beam. The tube also achieved an instantaneous bandwidth of ~15 GHz in G-band in the small signal regime. The all-copper circuit was fabricated in two layers using a UV-transparent polymer monofilament embedded in the photoresist to form the beam tunnel prior to electroforming. Effects arising from fabrication errors and target tolerances are discussed. This microfabrication technique and demonstration paves the way for a new era of vacuum electron devices that could extend into the 1-2 THz range with advances in high-current-density electron guns.