| 摘要 |
The life and performance of high pressure sodium vapor lamps using double wire ceramic seals and no exhaust tube is improved by an end closure and inlead structure which prevents condensation of sodium-mercury amalgam on sealing frit. One end of the arc tube has a plug portion which forms an integral part of the alumina tube without any sealing frit or glass intervening between portions. The plug portion includes a pedestal portion which projects inwardly from the outer region which is joined to the tube. The pedestal defines with the tube wall a ring chamber in which excess amalgam collects out of contact with any sealing frit. The other end of the tube is conventionally sealed by using sealing frit to cement an alumina plug but it is designed to run hotter to prevent condensation of amalgam at that end.
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