Historical development and future trends of vacuum electronics

Abstract

Vacuum electronics (VE) have dominated development and industrial growth in their application areas from the end of the 19th century to the end of 20th century. VE have contributed to basic concepts of physics and have enabled important basic inventions. Despite this bright past, in the meantime also a complete or partial replacement by new technologies such as solid-state electronics (SSE) occurred in several applications areas, triggered by the demand for new features and leading to new applications. Based on a review of the historical development of vacuum electronics from the basic inventions to the modern state of the art, the aim of this paper is to identify future trends and prospects of this field. The appearance of generic technology cycles, as in the case of radio-receiving tubes and cathode-ray display tubes, is discussed. Microwave tubes did experience only a partial replacement by solid-state devices and defended the high-power, high-frequency domain. The reason for their superiority in this domain is discussed. The development of the base technologies for VE, namely vacuum technology and electron source technology, is outlined, enabling further improvements. Besides the high-power, high-frequency domain of microwave tubes, VE technology applications with positive future prospects are addressed, e.g., space applications (long-lived microwave tubes, ion thrusters); thermionic energy converters; e-beam lithography; x-ray tubes; vacuum-based high-resolution characterization, and high-brightness beams for free electron lasers or particle accelerators. The continuous growth and increase in performance of solid-state electronics is shortly reviewed, SSE taking the lead with respect to total sales in the 1980s. Now, despite inherent advantages, solid-state electronics also seem to approach technical limitations. These include increasing energy consumption in conjunction with reduced long-term reliability when further scaling down. It is envisioned that vacuum nanoelectronics can help to overcome these limitations when scaling down feature sizes of integrated circuits below 22 nm.

Brief history of X-ray tube patents

“…However, the demand for increased output from the X-ray tube continued unabated in the following years. Among many companies, Philips, for instance, introduced the Maximus Rotalix Ceramic X-ray tube in 1989 [14]. This had a new rotating anode, which was the first tube that replaced the existing ball bearings with spiral groove bearings and a liquid-metal alloy as a lubricant.…”

“…Some X-ray examinations need very high-resolution images and do therefore require microfocus X-ray tubes that can generate very small focal spot sizes, typically below 50 mm in diameter. In fact, according to Gaertner [14], X-ray tubes have not experienced any recent decline and continue to grow with respect to total sales worldwide (in billions of US$, just considering data from 1970 up to 2010). The current development efforts worldwide are aimed mainly at better electron-beam focus control and improved cathodes.…”

Vacuum frequency mixer with a field emitter array

“…Therefore, they would work in harsh environments, such as spaceships, automobiles, and nuclear plants. 4,5 Possible applications are sensors and their amplifiers to detect environmental conditions and, in some cases, to transmit signals to a remote location. Receiving signals from a remote location may also be an important application.…”

Heating based model analysis for explosive emission initiation at metal cathodes

“…8,9 In this high voltage context, explosive electron emission has been reported. [10][11][12][13] A simple, qualitative explanation for initiation of the explosive emission is that an applied external voltage creates high electric fields (in the 10 7 −10 8 V/cm range) at cathode micro-protrusions.…”