| 摘要 |
PURPOSE:To obtain a high-pressure sodium lamp with improved life characteristic by providing a luminous tube in an outer tube made of alumina silicate glass and filled with inactive gas. CONSTITUTION:A luminous tube 1 is held by support wires 7, 8 respectively via electrode conductors 2, 3, and the support wires 7, 8 are provided in an airtightly sealed outer tube 11 via metal foils 9, 10 made of molybdenum. The outer tube 11 is made of alumina silicate glass, and it is filled with helium gas of about 2Torr. Alumina silica glass with an extremely small gas transparency loss is used for the outer tube 11, thereby the dissipation of the helium gas in the outer tube 11 can be suppressed during the lamp life, and an increase of the operating temperature of the luminous tube can be also suppressed to the utmost, thus the speed of dissipation of sodium atoms constituting the sodium amalgam 6 is suppressed. |
