This book grew out of a course taught by Professor Bigelow on vacuum techniques in electron microscopy. The information, however, should be useful to anyone dealing with vacuum systems. The goal of the book is to make operators comfortable operating and maintaining the vacuum systems on their instruments.
The first two chapters describe the characteristics of a vacuum and of the evacuation process. They present a brief history of the development of the vacuum sys- tem and the electron microscope up to the present-day instruments. Basic concepts and principles are developed with the use of mathematical relationships, graphs, and tables. Schematic diagrams of a vacuum system with its components are presented and the factors that determine the time it takes to pump down and the level of vacuum attainable are examined. Since many people are presently working with vacuum systems that have gauges that are calibrated in Torr and still think in terms of Torr, it is helpful that both Pascal and Torr units are given. The practical manner in which the material has been presented and the topics discussed emphasize the importance of understanding the operation and characteristics of the components of the vacuum system and makes one look forward with interest to the chapters that follow.
The next six chapters describe the various types of vacuum gauges and pumps: rough, oil diffusion, turbomolecular and molecular drag, ion, sublimation, and bulk getter, and cryogenic. Each is characterized as to operating principles, advantages and disadvantages, and capabilities. Vacuum problems with each system are discussed with problem symptoms and appropriate solutions. Many of these are directly from the author's personal experience with such systems over some 30 years.
After this lengthy discussion of all the characteristics of the components, chapter nine discusses the ways in which these are incorporated into six types of vacuum systems; a freeze-fractureietch apparatus; oil dif-