Thermionic energy conversion

Thermionic conversion is a method for converting heat directly into electrical energy. Unlike the conventional indirect methods for generating electricity from heat sources, no intermediate form of energy is required, and no working fluid--except the flow of the electrical charges themselves--are involved in the process. And unlike other direct conversion methods, there is no need for access to natural light (as required for photocells) or special chemicals (as required for fuel cells)--there are many available sources of thermal energy that can be utilized.The phenomenon of thermionic emission has been known since the late nineteenth century, but for many decades only sporadic and disconnected efforts were made to harness it for useful work. In the past few years, however, its potential for practical application has been recognized, and much research has now been done that supports the prospect that thermionic energy conversion will find increasing utility over the coming years. The purpose of this volume--the first of two--is to summarize what is known about the process for the benefit of a wide audience of technical readers who are not familiar with its potentials as well as to serve as a reference for those already in the field. (The second volume, now in preparation, will develop the more advanced scientific aspects of the process, describe the experience with actual hardware now operational, and estimate the limits of parameters that are unlikely to be exceeded in the near future.)Volume One opens with an introductory chapter that classifies thermionic converters by type and specifies their performance characteristics. The second chapter investigates the devices on a theoretical level by analyzing the ideal performance of the simplest configuration, which consists of a heated electrode and a collector electrode connected to a heat sink, the two separated and enclosed in an evacuated or vapor-filled space, and connected externally through an electrical load.The final two chapters take up, respectively, vacuum and vapor converters. The vacuum devices considered are diode, magnetic triode, and electrostatic triode converters; the vapor devices taken up include such converter configurations as cesium diodes, low- and high-pressure diodes, cesium diodes with additives, supplemented vapor diodes, ion emission triodes, and arc triodes.