Progress in Cryogenics: Volume 4—Edited by K. Mendelssohn (Heywood Books, 1964) 175 pages. 70s

✍ Scribed by H.M. Rosenberg

• Publisher: Elsevier Science
• Year: 1966
• Tongue: English
• Weight: 214 KB
• Volume: 6
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/0011-2275(66)90028-2

✦ Synopsis

into equation ( ) if 50 per cent of the appropriate density value is chosen for p. Values of 85 kOe (4.2 ° K) or 135 kOe (2-point) are then obtained. These are also approximately within the range of experimentally obtained results. 6

It should be pointed out, however, that the criterion given here is valid only for the case of an infinitely slow change of the exciting field Ha. In the case of finite speeds of change, an additional heat is developed which causes higher boundary temperatures TG or lower values of the fields which can be trapped. The heat conductivity of the substrate will also be of importance.

Especially good results can be obtained if the hollow cylinder is built up from discs with thin Nb3Sn surface layers with---contrary to references 5 and 8-interstices which have a low resistance to the flow of the normal component of helium II, too. In this manner, it should be possible, within the helium II range, to introduce the heat capacity of all the liquid helium contained in the cryostat in equation ( ).