One class of white dwarfs has almost purehelium atmospheres.
有一类白矮星的大气层几乎完全由纯氦气构成。
2
As the normal suppression method, purehelium is gradually replaced with He-Ar mixed gas for economical efficiency, especially the he content is more than 50%.
常用的抑制方法是侧吹氦气，而采用氦氩混合气体可降低生产成本，特别是当氦气含量高于50%时。
3
The authors give a novel conception that in order to increase the cooling capacity of a pulse tube refrigerator at 80K temperature range, refrigerant mixtures are introduced instead of purehelium.