| 摘要 |
724,105. Electric discharge lamps. HANOVIA CHEMICAL & MANUFACTURING CO. Jan. 31, 1952, No. 2659/52. Drawings to Specification. Class 39 (1). A H.P. electric discharge lamp for the production of U.V. radiation between 3200A and 3500Š comprises an U.V. light transmissive envelope e.g. of fused quartz and refractory glasses, at least a pair of spaced electrodes, and an ionizable medium comprising mercury and cadmium, the electrodes being spaced so that an electric discharge path in the medium has a length A in cms. related to the inner diameter B in cms. of the envelope, substantially acording to the formula LogeA equal to or less than B 3/2, the mercury being present in an amount sufficient when vaporized to provide a high pressure mercury discharge at a partial pressure of approximately 2 atmospheres at a power loading for a current of 3 to 4 amperes, of between 45 watts and 55 watts, preferably 50 watts, per square inch of envelope surface and the cadmium being present in an amount sufficient when vaporized to provide a partial pressure of approximately .002 atmospheres for the production of cadmium resonance radiation at 3261Š. In examples referred to B varies from 1.5 cms. to 3 cms. and A varies from 6 cms. to 180 cms. or from and including 12 per cent. to 10 per cent. less than these figures. The ionizable medium can consist, in vapour form, of about 99 per cent. by weight of mercury, 0.1 per cent. by weight of cadmium and 0.9 per cent. by weight of rare gas for starting an arc discharge, for a total pressure of about 2 atmospheres. The envelope may be enclosed within one or more envelopes of U.V. radiation transmitting glass which may be evacuated or contain an inert gas filling or a filling of a thermally insulating gas such as carbon dioxide. The electrodes may be tungsten or tantalum coils together with electron emitting materials such as thorium or barium. A third electrode may be added for starting the discharge. The rare gas filling may be argon, krypton or xenon at 1 to 30 mms. pressure. |
