204:. Baffles are often attached to the cold head to expand the surface area available for condensation, but these also increase the radiative heat uptake of the cryopump. Over time, the surface eventually saturates with condensate and thus the pumping speed gradually drops to zero. It will hold the trapped gases as long as it remains cold, but it will not condense fresh gases from leaks or backstreaming until it is regenerated. Saturation happens very quickly in low vacuums, so cryopumps are usually only used in high or ultrahigh vacuum systems.
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range. The cryopump operates on the principle that gases can be condensed and held at extremely low vapor pressures, achieving high speeds and throughputs. The cold head consists of a two-stage cold head cylinder (part of the vacuum vessel) and a drive unit displacer assembly. These together produce
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Regeneration of a cryopump is the process of evaporating the trapped gases. During a regeneration cycle, the cryopump is warmed to room temperature or higher, allowing trapped gases to change from a solid state to a gaseous state and thereby be released from the cryopump through a pressure relief
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Some cryopumps have multiple stages at various low temperatures, with the outer stages shielding the coldest inner stages. The outer stages condense high boiling point gases such as water and oil, thus saving the surface area and refrigeration capacity of the inner stages for lower boiling point
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As cooling temperatures decrease when using dry ice, liquid nitrogen, then compressed helium, lower molecular-weight gases can be trapped. Trapping nitrogen, helium, and hydrogen requires extremely low temperatures (~10K) and large surface area as described below. Even at this temperature, the
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Most production equipment utilizing a cryopump have a means to isolate the cryopump from the vacuum chamber so regeneration takes place without exposing the vacuum system to released gasses such as water vapor. Water vapor is the hardest natural element to remove from vacuum chamber walls upon
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by condensing them on a cold surface, but are only effective on some gases. The effectiveness depends on the freezing and boiling points of the gas relative to the cryopump's temperature. They are sometimes used to block particular contaminants, for example in front of a
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When regeneration is complete, the cryopump will be roughed to 50μm (50 milliTorr or μmHg), isolated, and the rate-of-rise (ROR) will be monitored to test for complete regeneration. If the ROR exceeds 10μm/min the cryopump will require additional purge time.
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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, enabled by the invention of better
172:. 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
176:'s manufacturing of integrated circuits. The use of cryopumps became common in semiconductor manufacturing worldwide, with expansions such as a cryogenics company founded jointly by Helix and
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exposure to the atmosphere due to monolayer formation and hydrogen bonding. Adding heat to the dry nitrogen purge-gas will speed the warm-up and reduce the regeneration time.
128:). There is a delay between the molecule impinging on the surface and rebounding from it. Kinetic energy will have been lost as the molecules slow down. For example,
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saturates, the effectiveness of a sorption pump decreases, but can be recharged by heating the zeolite material (preferably under conditions of low pressure) to
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closed-cycle refrigeration at temperatures that range from 60 to 80K for the first-stage cold station to 10 to 20K for the second-stage cold station, typically.
136:, but it can be cryotrapped. This effectively traps molecules for an extended period and thereby removes them from the vacuum environment just like cryopumping.
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it. The breakdown temperature of the zeolite material's porous structure may limit the maximum temperature that it may be heated to for regeneration.
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Sorption pumps are a type of cryopump that is often used as roughing pumps to reduce pressures from the range of atmospheric to on the order of 0.1
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can also refer to a somewhat different effect, where molecules will increase their residence time on a cold surface without actually freezing (
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lighter gases helium and hydrogen have very low trapping efficiency and are the predominant molecules in ultra-high vacuum systems.
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424:(2), Transactions of the Japan Society of Refrigerating and Air Conditioning Engineers, Volume 11, Issue 2, pp. 89-99: 89,
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160:. The key refrigeration technology was discovered in the 1950s by two employees of the Massachusetts-based company
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Transactions of the Japan
Society of Refrigerating and Air Conditioning Engineers
292:(1875). "4. Preliminary Note "On a New Method of obtaining very perfect Vacua".
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Cryopumps are commonly cooled by compressed helium, though they may also use
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An experimental investigation of pulse tube refrigeration heat pumping rate
250:(10 Torr), while lower pressures are achieved using a finishing pump (see
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Journal of Vacuum
Science & Technology A: Vacuum, Surfaces, and Films
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442:
Bridwell, M. C.; Rodes, J. G. (1985). "History of the modern cryopump".
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The cryopump provides fast, clean pumping of all gases in the 10 to 10
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118:, even though the physical mechanism is the same as for a cryopump.
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Baechler, Werner G. (1987). "Cryopumps for research and industry".
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by coating the cold head with highly adsorbing materials such as
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to keep out water. In this function, they are called a
498:(2nd ed.). New York: VCH Publisher. pp.
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200:, or stand-alone versions may include a built-in
144:Early experiments into cryotrapping of gasses in
300:. Cambridge University Press (CUP): 348–349.
294:Proceedings of the Royal Society of Edinburgh
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102:to trap backstreaming oil, or in front of a
382:Gifford, W. E.; Longsworth, R. C. (1965),
362:Gifford, W. E.; Longsworth, R. C. (1964),
168:. This technology came to be known as the
69:Learn how and when to remove this message
32:This article includes a list of general
484:Van Atta, C. M.; M. Hablanian (1991) .
450:(3). American Vacuum Society: 472–475.
280:
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526:. Bradley, IL: Lindsay Publications.
148:were conducted as far back as 1874.
371:, Trans. ASME, J. Eng. Ind. 63, 264
523:Procedures in Experimental Physics
223:Cryopumps are often combined with
38:it lacks sufficient corresponding
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151:The first cryopumps mainly used
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487:"Vacuums and Vacuum Technology"
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341:10.1016/0042-207x(87)90078-9
494:and George L. Trigg (ed.).
335:(1–2). Elsevier BV: 21–29.
263:valve into the atmosphere.
85:or a "cryogenic pump" is a
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412:Matsubara, Yoichi (1994),
401:, Adv. Cryog. Eng. 12, 608
397:Longsworth, R. C. (1967),
386:, Adv. Cryog. Eng. 11, 171
170:Gifford-McMahon cryocooler
414:"Pulse Tube Refrigerator"
306:10.1017/s0370164600029734
164:, William E. Gifford and
365:Pulse tube refrigeration
216:gases such as nitrogen.
496:Encyclopedia of Physics
132:does not condense at 8
53:more precise citations.
162:Arthur D. Little Inc.
384:Surface heat pumping
456:1985JVSTA...3..472B
430:2011TRACE..11...89M
16:Type of vacuum pump
229:activated charcoal
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528:, Chapter 3
184:) in 1981.
158:cryocoolers
89:that traps
87:vacuum pump
51:introducing
536:Categories
275:References
202:cryocooler
34:references
500:1330–1334
472:0734-2101
349:0042-207X
314:0370-1646
235:. As the
188:Operation
116:cold trap
112:waterpump
520:(1938).
182:jp:アルバック
130:hydrogen
108:cryotrap
83:cryopump
452:Bibcode
426:Bibcode
237:sorbent
233:zeolite
194:dry ice
140:History
134:kelvins
95:vapours
47:improve
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329:Vacuum
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241:outgas
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547:Gases
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