SVC Education Program
Detailed SVC Course Syllabus
Cryogenic high vacuum pumps are used on a wide variety of vacuum deposition and process equipment (evaporation, sputtering, ion implant), space simulation systems, and on analytical instruments. They produce high pumping speeds for all gases and work over a wide range of pressures. To use these pumps effectively, it is helpful to understand their advantages as well as their limitations. The focus will be on cryopumps using closed-loop helium gas refrigerators, but other types of liquid cryogen and sorption pumps will be discussed.
Commercial cryogenic vacuum pumps typically use the Gifford-McMahon cycle to produce temperatures near absolute zero. Gases are condensed within the cryopump and turned to solids or are held in special adsorbent materials. After pumping a vacuum chamber for many days or weeks, cryopumps reach their capacity limits and need to be regenerated by warming them to release the frozen gases. Through knowledge of pump characteristics, the operating time between regenerations can be calculated and optimized. Proper use of cryopumps can reduce pumpdown time to process conditions and minimize maintenance requirements. Selection and sizing of cryopumps, as well as rough pumps for regeneration, will be covered.
The use of cryopumps in different applications will be discussed, particularly for sputtering, evaporation, ion implantation, and other important processes. Because each of these processes uses a different set of gases at widely varying flow rates, the behavior of cryopumps is different in each process. The influence of water vapor on cryopumped systems will be covered in detail, as well as methods for reducing the impact of water vapor on pumpdown time. Use of water vapor pumps, such as liquid nitrogen cooled surfaces or closed-loop refrigeration systems, like those made by Polycold and others, will be discussed.
The course is designed for users and operators of vacuum systems, process engineers, equipment designers, and maintenance staff. You will learn how to best use and maintain your cryopumps.
Some of the topics to be covered:
Text: reprint of Cryogenic Pumps chapter from “Handbook of Vacuum Science and Technology”, Academic Press, 1998 ISBN 0-12-352065-7
Instructor: Gary S. Ash, Castle Brook Corporation