| 摘要 |
528,577. Discharge lamps. QUARZLAMPEN GES. April 22, 1939, No. 12197. Convention date, April 23, 1938. [Class 39 (i)] The electrodes of a high-pressure metal vapour lamp with unactivated electrodes consist of wires such that if i is the working current in amperes and d the diameter of the electrodes in millimetres 5<i/d<SP>2</SP><15, and preferably 7<i/d<SP>2</SP><10. The length of the portion of the cathode projecting into the tube is greater than 5 millimetres, preferably greater than 8 millimetres, but less than 15 millimetres. The cathode wire is so dimensioned that its temperature in the neighbourhood of the point when the arc impinges on it is about 3,000‹ K. In the arrangement shown the electrodes 2 are surrounded by tubes 3 of insulating material which prevents metallic deposits on the wall of the tube from reaching the electrode. Short tubes of quartz &c. may serve as distance pieces to prevent the electrodes from touching the tubes 3. Rings 6 on the inner side of the envelope diminish sputtering on to it. Examples of dimensions, pressures and operating currents are given.
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