Cooling liquid He4 down to 0.43 K

✍ Scribed by J.M. Goldschvartz; P. Minderhout

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 233 KB
• Volume: 17
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(77)90150-3

✦ Synopsis

tacturer and that better results were obtained if the seal was not pressurized before cool-down. At a temperature of about 2 K no leakage from the cell could be detected at pressures below 12 bars, however, repeatedly, leaks occured above this pressure. These leaks were small, typically < 3 x 10-Tatm cm3s -~ and in fact during the course of our experiment a pressure of 20.0 +-0.3 bars was held in the cavity for a period of about 48 h, at a temperature of 0.6 K.

We believe that this is the first reported use of such a seal using liquid helium. The bonding of optical windows in cryostats is an obvious application of these seals in the field of cryogenics, particularly as they are so flexible that only low sealing loads need be applied. This means that optical materials much less strong than sapphire may be sealed without risk of damage to the window.

The author wishes to thank the staff of the lnstitut Laue-Langevin and P.E. Chorley of Avica Equipment Ltd. for their aid in testing and designing this cell.