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前言极低温的获得不仅仅以绝对零度为目标,而且对2.6毫K时液~3He的超流转变,1.1毫K时固~3He核自旋系的有序化这样一些基础物理中重要现象的发现来说也是重要的。这些现象得以证实正是取决于能长期可靠地维持毫K,微K温度这一实验技术上的进展。以前,为了获得低于1K的温度,应用顺磁性盐的绝热去磁法。而现在用~3He—~4He稀释致冷装置取代它即能获得2～3毫K的温度。而且维持这样的低温达半年以上正在成为可能。因此,以这种稀释致冷机为基础,同时可采用波麦朗邱克冷却、核绝热去磁法
Introduction Cryogenic temperatures are not only targeted at absolute zero temperatures, but also important fundamental physics phenomena such as superfluid transitions at ~3.6 K at ~3.6 K, and the ordering of solid ~ 3He nuclear spin systems at 1.1 mm K It is also important to discover. These phenomena have been confirmed precisely by the experimental technological progress that can maintain the milli-K and micro-K temperature reliably for a long period of time. Previously, in order to obtain temperatures below 1 K, paramagnetic salt adiabatic demagnetization was applied. And now ~ 3He- ~ 4He dilution refrigeration device to replace it can get 2 ~ 3 milli-K temperature. And maintaining such a low temperature for more than six months is becoming possible. Therefore, based on this type of dilution cooler, Polanyki cooling, nuclear adiabatic demagnetization