Hermetic sealing off the stainless steel pumping tube

摘要

Manufacturing special ampoules for investigations of alkali metal vapours we came across some technologically very demanding operations as are shaping of approx. 0,008 mm thick stainless steel (SS) membrane, fixing it on the massive ring, hermetic sealing-off by pinching the SS thick-wall tube during evacuation, in such a way that in the removed ampoule vacuum remains unspoiled, etc. The last procedure, which is an ordinary technique for Cu- and Al-tubes, was adapted and successfully performed on SS-connection. Instead of cold welding we used the combination of cold and hot technique. We have studied the geometry of squeezed tube, the weld formation from melted steel at different dimension and pressure conditions ; also tightness and degassing have been measured. The article discusses technology and some testing results that, according to our knowledge, has not been described yet.