真空丧失条件下液氦容器安全性试验

真空丧失对液氦容器的安全性是一大威胁,可能会造成十分严重的后果。通过试验,利用氦气及空气作为介质,对低温液氦容器在真空层发生泄漏情况下的漏热进行了研究。结果表明,多层绝热结构对于真空遭到破坏后的液氦容器能够起到一定的保护作用,而渗入到真空绝热层中气体的性质对于最终漏热情况也有影响,发现空气的“破坏力”明显小于氦气。

Safety experiment for loss of vacuum on a LHe vessel

Sudden loss of the vacuum of a liquid helium container raises serious safety concerns.Following the gas venting,dramatic heat leakage into the LHe is expected to cause a severe pressure rise due to the boiling of the helium.In addition,cold helium vapor of extremely low temperatures could result in catastrophic damage if not appropriately disposed.In this paper,we present the results of helium and air exposure experiments on a LHe vessel of a volume of approximately 10 liters with various insulation designs,namely,absence of insulation,20 layers or 50 layers of super-insulation.It is found that,the installation of super-insulation could work as a thermal buffer between the room temperature gas entering the vacuum space and the LHe after the insulating vacuum is compromised,effectively reducing the heat inflow into the cryogenic vessel.Also,the results show that,as far as the LHe is concerned,venting air into the insulating vacuum brings about less serious damage than venting helium.