Editing Helium (section)

==== Minor commercial and recreational uses ====
Helium as a breathing gas has no [[Nitrogen narcosis|narcotic properties]], so helium mixtures such as [[Trimix (breathing gas)|trimix]], [[heliox]] and [[Trimix (breathing gas)#Heliair|heliair]] are used for [[deep diving]] to reduce the effects of narcosis, which worsen with increasing depth.<ref>{{Cite journal |last1=Fowler |first1=B. |last2=Ackles |first2=K. N. |first3=Porlier |last3=G |date=1985 |title=Effects of inert gas narcosis on behavior—a critical review |journal=Undersea Biomedical Research |pmid=4082343 |url=http://archive.rubicon-foundation.org/3019 |access-date=2008-06-27 |volume=12 |issue=4 |pages=369–402 |archive-url=https://web.archive.org/web/20101225052236/http://archive.rubicon-foundation.org/3019 |archive-date=2010-12-25 |url-status=usurped }}</ref><ref name="thomas">{{Cite journal |author=Thomas, J. R. |date=1976 |title=Reversal of nitrogen narcosis in rats by helium pressure |journal=Undersea Biomed. Res. |volume=3 |issue=3 |pages=249–59 |pmid=969027 |url=http://archive.rubicon-foundation.org/2771 |access-date=2008-08-06 |archive-url=https://web.archive.org/web/20081206035952/http://archive.rubicon-foundation.org/2771 |archive-date=2008-12-06 |url-status=usurped }}</ref> As pressure increases with depth, the density of the breathing gas also increases, and the low molecular weight of helium is found to considerably reduce the effort of breathing by lowering the density of the mixture. This reduces the [[Reynolds number]] of flow, leading to a reduction of [[turbulent flow]] and an increase in [[laminar flow]], which requires less breathing.<ref>{{Cite journal| author = Butcher, Scott J.| author2 = Jones, Richard L.| author3 = Mayne, Jonathan R.| author4 = Hartley, Timothy C.| author5 = Petersen, Stewart R.| title = Impaired exercise ventilatory mechanics with the self-contained breathing apparatus are improved with heliox| journal = European Journal of Applied Physiology| volume = 101| issue = 6|date = 2007| doi = 10.1007/s00421-007-0541-5| pmid = 17701048| pages = 659–69| s2cid = 7311649}}</ref><ref name="BOCheox21">{{cite web |url=http://www.bochealthcare.co.uk/en/products/heliox/index.shtml |title=Heliox21 |publisher=Linde Gas Therapeutics |date=27 January 2009 |access-date=13 April 2011 |archive-url=https://web.archive.org/web/20110910232729/http://www.bochealthcare.co.uk/en/products/heliox/index.shtml |archive-date=10 September 2011 |url-status=live }}</ref> At depths below {{convert|150|m|ft}} divers breathing helium-oxygen mixtures begin to experience tremors and a decrease in psychomotor function, symptoms of [[high-pressure nervous syndrome]].<ref name="HungerBennett">{{cite journal |last1=Hunger | first1=W. L. Jr. |first2=P. B. |last2=Bennett |title=The causes, mechanisms and prevention of the high pressure nervous syndrome |journal=Undersea Biomed. Res. |volume=1 |issue=1 |pages=1–28 |date=1974 |issn=0093-5387 |oclc=2068005 |pmid=4619860 |url=http://archive.rubicon-foundation.org/2661 |access-date=2008-04-07 |archive-url=https://web.archive.org/web/20101225053451/http://archive.rubicon-foundation.org/2661 |archive-date=2010-12-25 |url-status=usurped }}</ref> This effect may be countered to some extent by adding an amount of narcotic gas such as hydrogen or nitrogen to a helium–oxygen mixture.<ref>{{Cite journal |author=Rostain, J. C. |author2=Gardette-Chauffour, M. C. |author3=Lemaire, C. |author4=Naquet, R. |title=Effects of a H<sub>2</sub>-He-O<sub>2</sub> mixture on the HPNS up to 450 msw |journal=Undersea Biomed. Res. |volume=15 |issue=4 |pages=257–70 |date=1988 |oclc=2068005 |pmid=3212843 |url=http://archive.rubicon-foundation.org/2487 |access-date=2008-06-24 |archive-url=https://web.archive.org/web/20081206035912/http://archive.rubicon-foundation.org/2487 |archive-date=2008-12-06 |url-status=usurped }}</ref>

[[Helium–neon laser]]s, a type of low-powered gas laser producing a red beam, had various practical applications which included [[barcode reader]]s and [[laser pointer]]s, before they were almost universally replaced by cheaper [[diode laser]]s.<ref name="nbb" />

For its inertness and high [[thermal conductivity]], neutron transparency, and because it does not form radioactive isotopes under reactor conditions, helium is used as a heat-transfer medium in some [[gas-cooled reactor|gas-cooled nuclear reactor]]s.<ref name="nostrand" />

Helium, mixed with a heavier gas such as xenon, is useful for [[thermoacoustic refrigeration]] due to the resulting high [[heat capacity ratio]] and low [[Prandtl number]].<ref>{{Cite journal|title=Working gases in thermoacoustic engines |journal=The Journal of the Acoustical Society of America |date=1999 |volume=105 |issue=5 |pages=2677–2684 |doi=10.1121/1.426884|author1 = Belcher, James R.|pmid=10335618|bibcode = 1999ASAJ..105.2677B|author2=Slaton, William V.|author3=Raspet, Richard|author4=Bass, Henry E.|author5=Lightfoot, Jay|doi-access=free}}</ref> The inertness of helium has environmental advantages over conventional refrigeration systems which contribute to ozone depletion or global warming.<ref>{{Cite book|title=Mending the Ozone Hole: Science, Technology, and Policy |author=Makhijani, Arjun |author2=Gurney, Kevin |publisher=MIT Press |date=1995 |isbn=978-0-262-13308-1}}</ref>

Helium is also used in some [[hard disk drive]]s.<ref>{{Cite web|url=https://arstechnica.com/information-technology/2013/11/hgst-balloons-disk-capacity-with-helium-filled-6tb-drive/|title=HGST balloons disk capacity with helium-filled 6TB drive|first=Sean|last=Gallagher|date=November 4, 2013|website=Ars Technica|access-date=June 14, 2017|archive-url=https://web.archive.org/web/20170707231259/https://arstechnica.com/information-technology/2013/11/hgst-balloons-disk-capacity-with-helium-filled-6tb-drive/|archive-date=July 7, 2017|url-status=live}}</ref>