High pressure sodium vapour lamp - with an increased lifetime and stable arc voltage

摘要

The high pressure sodium vapour lamp has two electrodes in a tube constructed in a material which is highly resistant to heat and transparent to light pref. a ceramic. The tube is filled with a rare gas pref. xinon with Na, Hg and/or Cd as additives at saturated vapour pressure at the temp. of use. The quantity of Hg and/or Cd is calculated as 0.5 to 5 microm. pref. 0.5 to 2.5 microns per cm. length of arc. The lamp functions for longer and during the time of use, the arc voltage stays almost constant without any tendency to extinguish.