Editing Cryopump (section)

==History==
Early experiments into cryotrapping of gasses in [[Activated carbon|activated charcoal]] were conducted as far back as 1874.<ref>{{cite journal | last1=Tait | first1=P. G. | last2=Dewar | first2=James |author-link2=James Dewar| title=4. Preliminary Note "On a New Method of obtaining very perfect Vacua. | journal=Proceedings of the Royal Society of Edinburgh | publisher=Cambridge University Press (CUP) | volume=8 | year=1875 | issn=0370-1646 | doi=10.1017/s0370164600029734 | pages=348–349}}</ref>

The first cryopumps mainly used [[liquid helium]] to cool the pump, either in a large liquid helium reservoir, or by continuous flow into the cryopump. However, over time most cryopumps were redesigned to use gaseous helium,<ref>{{cite journal | last=Baechler | first=Werner G. | title=Cryopumps for research and industry | journal=Vacuum | publisher=Elsevier BV | volume=37 | issue=1–2 | year=1987 | issn=0042-207X | doi=10.1016/0042-207x(87)90078-9 | pages=21–29| bibcode=1987Vacuu..37...21B }}</ref> enabled by the invention of better [[cryocooler]]s. The key refrigeration technology was discovered in the 1950s by two employees of the Massachusetts-based company [[Arthur D. Little|Arthur D. Little Inc.]], William E. Gifford and [[Howard O. McMahon]]. This technology came to be known as the [[Cryocooler#GM-refrigerators|Gifford-McMahon cryocooler]].<ref>{{citation |last1=Gifford |first1=W. E.| last2=Longsworth | first2=R. C. | title=Pulse tube refrigeration | publisher=Trans. ASME, J. Eng. Ind. 63, 264 | year=1964 | url=https://www.cryomech.com/wp-content/uploads/2019/01/WilliamGiffordPulseTube.pdf}}</ref><ref>{{citation |last1=Gifford |first1=W. E. | last2=Longsworth | first2=R. C.| title=Surface heat pumping | publisher=Adv. Cryog. Eng. 11, 171 | year=1965}}</ref><ref>{{citation | last1=Longsworth | first1=R. C. | title=An experimental investigation of pulse tube refrigeration heat pumping rate | publisher=Adv. Cryog. Eng. 12, 608 | year=1967}}</ref><ref>{{citation |last1=Matsubara | first1=Yoichi | title=Pulse Tube Refrigerator | journal=Transactions of the Japan Society of Refrigerating and Air Conditioning Engineers | publisher=Transactions of the Japan Society of Refrigerating and Air Conditioning Engineers, Volume 11, Issue 2, pp. 89-99 | year=1994 | volume=11 | issue=2 | page=89 | bibcode=2011TRACE..11...89M | url=https://ui.adsabs.harvard.edu/abs/2011TRACE..11...89M/abstract}}</ref> In the 1970s, the Gifford-McMahon cryocooler was used to make a vacuum pump by Helix Technology Corporation and its subsidiary company Cryogenic Technology Inc. In 1976, cryopumps began to be used in [[IBM]]'s manufacturing of integrated circuits.<ref>{{cite journal | last1=Bridwell | first1=M. C. | last2=Rodes | first2=J. G. | title=History of the modern cryopump | journal=Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films | publisher=American Vacuum Society | volume=3 | issue=3 | year=1985 | issn=0734-2101 | doi=10.1116/1.573017 | pages=472–475| bibcode=1985JVSTA...3..472B }}</ref> The use of cryopumps became common in semiconductor manufacturing worldwide, with expansions such as a cryogenics company founded jointly by Helix and [[Ulvac|ULVAC]] ([[jp:アルバック]]) in 1981.