High pressure sodium vapour lamp - has multiple turn wire starting aid coiled around arc tube intermediate to electrodes

摘要

The high pressure arc discharge lamp comprises an arc tube having an electrode at each end. A multiple turn wire starting aid is coiled around the arc tube intermediate the electrodes and electrically connected to only one of the electrodes. The coiled starting aid extends longitudinally along the arc tube a distance that is at least 10% of the arc length. The starting aid is made of tungsten or molybdenum wire and the arc tube has a fill including sodium, mercury and a Penning gas mixture. The starting aid is connected to the electrode through a temperature activated switch.