| 摘要 |
PURPOSE:To prevent any inconvenience of the device other than the lamp such as a stabilizer by installing a high temperature part with a specified temperature during usual lighting in the conductor of the emission tube of a high pressure sodium lamp. CONSTITUTION:A high temperature part 12 the temperature of which is at least 2,200 deg.K during usual lighting is included in the conductor 11 of the emission tube 2 of a high pressure sodium lamp. If the vapor of a rare gas used as the starting substance leaks into an outer tube 1 due to gas leakage of the emission tube during lighting, the leaked substance is thermally ionized in the high temperature part 12 and the ionized substance and thermions discharged from the high temperature part 12 form a discharge path in the leaked gas and the vapor to produce an arc spot in the high temperature part 12. Since the temperature of the arc spot becomes very high, the arc spot is evaporated to cause breakdown of the wire thereby breaking down the electric circuit installed inside the lamp.
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