tag:blogger.com,1999:blog-13869903.post4593928741038440740..comments2024-03-28T04:15:44.459-05:00Comments on nanoscale views: 3HeDouglas Natelsonhttp://www.blogger.com/profile/13340091255404229559noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-13869903.post-9068285656211023152009-11-05T20:40:30.879-06:002009-11-05T20:40:30.879-06:00In the long term, dry tech is a good direction to ...In the long term, dry tech is a good direction to go. Still, pulse tubes aren't the solution to everything. They're hideous power hogs. Needing an 11 kW constant electrical power to give 1 W of cooling power at 4.2 K is awful, when you remember that that same cooling power is available in the latent heat of 1 liter of liquid 4He. They also still have some vibrational issues. Finally, as anon. points out, to get really low temperatures without cryogens is hard. The best approach would be to do demag refrigeration, which can get you probably 12-24 hours at 100 mK starting from 4.2K, assuming no measurement heat load at all. If only the various all-electrical refrigeration schemes worked better....Douglas Natelsonhttps://www.blogger.com/profile/13340091255404229559noreply@blogger.comtag:blogger.com,1999:blog-13869903.post-33358278226169199902009-11-05T15:52:00.049-06:002009-11-05T15:52:00.049-06:00Even a dry fridge needs mixture, unless someone ha...Even a dry fridge needs mixture, unless someone has invented a pulse tube that goes < 100 mK. <br /><br />BTW, I've heard single-shot charcoal sorbs can pump He-4 down to 0.7 K, though it's not very commonly done.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-88564699556833436792009-11-05T15:20:21.483-06:002009-11-05T15:20:21.483-06:00Dry fridges are the way to go. Once people learn ...Dry fridges are the way to go. Once people learn en masse that those now exist, we'll never have to deal with bloody cryogens. Nevermind the carbon emissions...jonahhttps://www.blogger.com/profile/00766485331481072213noreply@blogger.comtag:blogger.com,1999:blog-13869903.post-31647939558934538082009-11-05T13:11:51.088-06:002009-11-05T13:11:51.088-06:00I shouldn't have inhaled all those helium ball...I shouldn't have inhaled all those helium balloons.Patricknoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-29983988897242709402009-11-04T17:10:21.246-06:002009-11-04T17:10:21.246-06:00The phrase "one neutron shy of a typical heli...The phrase "one neutron shy of a typical helium atom" would be a useful euphemism for some people I know, analogous to "a few cards shy of a full deck" or something.DanMnoreply@blogger.com