对于真空获得来说,最感棘手的工作是仅当设备冷却时,漏孔才显现出来。这就是所谓“冷漏”现象。经常会有这样的情况,即在常温下漏孔确实是存在的,但由于漏率很小,即使采用高灵敏度检漏仪也检验不出来。然而当系统长时期承受冷热冲击后,特别是在使用低温液体(液氮、液氦等)冷却后,由于材料的胀缩率不同,加之较高的气体密度和较低的粘 The trickiest job for vacuum access is to see leaks only when the device cools. This is the so-called “cold drain” phenomenon. Often there is such a situation that the leak is indeed present at room temperature but due to the small leak rate, even a highly sensitive leak detector can not be tested. However, when the system is subjected to thermal shock over a long period of time, especially after cooling with cryogenic liquid (liquid nitrogen, liquid helium, etc.) due to the different shrinkage rates of the materials, combined with higher gas density and lower viscosity