RF Properties and Their Variations in a 3D Printed Klystron Circuit and Cavities

TL;DR

This paper demonstrates that 3D printed RF cavities and integrated circuits can be manufactured efficiently with promising RF properties, potentially revolutionizing the production of high-power vacuum devices.

Contribution

It introduces a novel additive manufacturing process for RF components, showing that 3D printed cavities have acceptable RF properties and tuning capabilities.

Findings

Un-tuned cavity frequency varies less than 5% from intended

Q factors exceed 1200 in 3D printed cavities

138 MHz tuning range achieved with unoptimized tuning pins

Abstract

Presently, the manufacturing of active RF devices like klystrons is dominated by expensive and time consuming cycles of machining and brazing. In this article we characterize the RF properties of X-band klystron cavities and an integrated circuit manufactured with a novel additive manufacturing process. Parts are 3D printed in 316L stainless steel with direct metal laser sintering, electroplated in copper, and brazed in one simple braze cycle. Standalone test cavities and integrated circuit cavities were measured throughout the manufacturing process. Un-tuned cavity frequency varies by less than 5% of intended frequency, and Q factors reach above 1200. A tuning study was performed, and unoptimized tuning pins achieved a tuning range of 138 MHz without compromising Q. Klystron system performance was simulated with as-built cavity parameters and realistic tuning. Together, these results show promise that this process can be used to cheaply and quickly manufacture a new generation of highly integrated high power vacuum devices.