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Title: Long-life micro vacuum chamber for a micromachined cryogenic cooler

Micromachined cryogenic coolers can be used for cooling small electronic devices to improve their performance. However, for reaching cryogenic temperatures, they require a very good thermal insulation from the warm environment. This is established by a vacuum space that for adequate insulation has to be maintained at a pressure of 0.01 Pa or lower. In this paper, the challenge of maintaining a vacuum chamber with a volume of 3.6 × 10{sup −5} m{sup 3} and an inner wall area of 8.1 × 10{sup −3} m{sup 2} at a pressure no higher than 0.01 Pa for five years is theoretically analyzed. The possible sources of gas, the mechanisms by which these gases enter the vacuum space and their effects on the pressure in the vacuum chamber are discussed. In a long-duration experiment with four stainless steel chambers of the above dimensions and equipped with a chemical getter, the vacuum pressures were monitored for a period of two years. In that period, the measured pressure increase stayed within 0.01 Pa. This study can be used to guide the design of long-lifetime micro vacuum chambers that operate without continuous mechanical pumping.
Authors:
; ; ; ;  [1]
  1. Energy, Materials and Systems, Faculty of Science and Technology, University of Twente, 7500 AE Enschede (Netherlands)
Publication Date:
OSTI Identifier:
22479723
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films; Journal Volume: 33; Journal Issue: 6; Other Information: (c) 2015 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; COOLING; DESIGN; ELECTRONIC EQUIPMENT; HEAT EXCHANGERS; PUMPING; STAINLESS STEELS; THERMAL INSULATION; WALLS