George N. Hatsopoulos

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.

U.S. Competitiveness: Beyond the Trade Deficit

Large trade deficits and the corresponding increase in U.S. international indebtedness have raised concerns about the long-run competitiveness of the United States. But being competitive requires more than balance in our foreign trade; it requires an improving standard of living. The long-term U.S. competitive problem is largely caused by low saving rates, high costs of capital, and the resulting inadequate level of both visible and invisible investment. As long as the U.S. national saving rate remains far below that of all our major competitor nations, there is little chance for restoring Americas international economic position.

A Unified Quantum Theory of Mechanics and Thermodynamics. Part I. Postulates

A unified axiomatic theory that embraces both mechanics and thermodynamics is presented in three parts. It is based on four postulates; three are taken from quantum mechanics, and the fourth is the new disclosure of the existence of quantum states that are stable (Part I). For nonequilibrium and equilibrium states, the theory provides general original results, such as the relation between irreducible density operators and the maximum work that can be extracted adiabatically (Part IIa). For stable equilibrium states, it shows for the first time that the canonical and grand canonical distributions are the only stable distributions (Part IIb). The theory discloses the incompleteness of the equation of motion of quantum mechanics not only for irreversible processes but, more significantly, for reversible processes (Part IIb). It establishes the operational meaning of an irreducible density operator and irreducible dispersions associated with any state, and reveals the relationship between such dispersions and the second law (Part III).

A unified quantum theory of mechanics and thermodynamics. Part IIb. Stable equilibrium states

Part IIb presents some of the most important theorems for stable equilibrium states that can be deduced from the four postulates of the unified theory presented in Part I. It is shown for the first time that the canonical and grand canonical distributions are the only distributions that are stable. Moreover, it is shown that reversible adiabatic processes exist which cannot be described by the dynamical equation of quantum mechanics. A number of conditions are discussed that must be satisfied by the general equation of motion which is yet to be discovered.

A unified quantum theory of mechanics and thermodynamics. Part IIa. Available energy

AbstractPart II of this three-part paper presents some of the most important theorems that can be deduced from the four postulates of the unified theory discussed in Part I. In Part IIa, it is shown that the maximum energy that can be extracted adiabatically from any system in any state is solely a function of the density operator

Where is the entropy challenge

\hat \rho

Transport effects in cesium thermionic converters

associated with the state. Moreover, it is shown that for any state of a system, nonequilibrium, equilibrium or stable equilibrium, a unique propertyS exists which is proportional to the total energy of the system minus the maximum energy that can be extracted adiabatically from the system in combination with a reservoir. For statistically independent systems, propertyS is extensive, it is invariant during all reversible processes, and it increases during all irreversible processes.

Thermionic power generator

This part of the paper concludes the presentation of the unified theory. It is shown that the theory requires the existence of, and applies only to, irreducible quantal dispersions associated with pure or mixed states. Two experimental procedures are given for the operational verification of such dispersions. Because the existence of irreducible dispersions associated with mixed states is required by Postulate 4 of the theory, and because Postulate 4 expresses the basic implications of the second law of classical thermodynamics, it is concluded that the second law is a manifestation of phenomena characteristic of irreducible quantal dispersions associated with the elementary constituents of matter.