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(一) 概述 随着宇宙空间技术、核武器和原子能工业、红外探测技术和低温电子学的发展,低温技术作为一种新技术来应用,越来越显示它的重要性。低温技术的发展经历了一个此较长的过程:1878年液化氮气获得77°K低温;1898年液化氢气获得20.4°K低温;1908年实验室液化了氦,获得了4.2°K的低温;1933年用液氦减压的方法获得了0.27°K的低温;1956年用多级绝热去磁的方法获得了0.00002°K的低温。但是对77°K以下的各
(A) Overview With the development of space technology, nuclear weapons and atomic energy industry, infrared detection technology and low temperature electronics, cryogenic technology as a new technology to be applied, more and more shows its importance. The development of cryogenic technology has undergone this long process: liquefied nitrogen gets a low temperature of 77 ° K in 1878; liquefied hydrogen gets a low temperature of 20.4 ° K in 1898; laboratory liquefied helium in 1908, obtaining a low temperature of 4.2 ° K; 1933 In the year, a low temperature of 0.27 ° K was obtained by the decompression of liquid helium. In 1956, a multi-stage adiabatic demagnetization method was used to obtain a low temperature of 0.00002 ° K. But for each 77 ° K below