High pressure sodium vapor lamp stabilized for pulse operation
AssigneeGeneral Electric Company
InventorJack M. Strok
Life of this patent
Estimating the term…
Abstract
High pressure sodium vapor lamps operated on sonic frequency pulses with short duty cycle in order to raise the color temperature are subject to arc instability near the electrodes and to overheating of the end closures, particularly that at the anode end when unidirectional pulsing is used. Stability and long life is achieved and overheating is prevented by using electrodes of cross-sectional area from 0.3 to 0.4 times the envelope cross section and lengthening the distance from closure to electrode tip so that the arc gap is less than 80% of the gas column length.
Claims11
A high pressure sodium vapor lamp arc tube for high frequency short duty cycle pulse operation comprising:
- an elongated light-transmitting ceramic tube having closures sealing its ends and containing a filling of sodium-mercury amalgam;
- a pair of electrodes supported from said closures at opposite ends of said tube, each comprising a body portion mounted on an axial tungsten shank,
- the insertion depth of said electrodes into the tube being at least 10% of the gas column length therein,
- and the ratio of the cross-sectional area of the body portion of said electrodes to the cross-sectional area of the bore of the tube being in the range of 0.3 to 0.4.
A high pressure sodium vapor lamp arc tube for high frequency short duty cycle pulse operation comprising:
- an elongated light-transmitting ceramic tube having closures sealing its ends and containing a filling of starting gas and sodium-mercury amalgam;
- a pair of electrodes supported from said closures at opposite ends of the tube, each comprising an axial tungsten shank having tungsten wire coiled around it,
- the insertion depth of said electrodes into the tube ends determining an arc gap between electrodes less than 80% of the gas column length in said tube,
- and the ratio of the cross-sectional area of the coiled portion of said electrodes to the cross-sectional area of the bore of the tube being in the range of 0.3 to 0.4.
A high pressure sodium vapor lamp arc tube for high frequency short duty cycle unidirectional pulse operation comprising:
- an elongated light-transmitting ceramic tube having closures sealing its ends and containing a filling of sodium-mercury amalgam,
- a pair of electrodes supported from said closures at opposite ends of the tube, each comprising a body portion mounted on an axial tungsten shank, said body portion in the cathode electrode comprising tungsten wire helically coiled around said shank and including electron-emissive material in the interstices between turns,
- the insertion depth of said electrodes into the tube ends determining an arc gap between electrodes less than 80% of the gas column length in said tube,
- and the ratio of the cross-sectional area of the body portion of the electrodes to the cross-sectional area of the bore of the tube being in the range of 0.3 to 0.4.
Dependencies are inferred from the claim text.