Cathode for high intensity discharge lamp

摘要

A cathode for a discharge lamp comprises a longitudinally extending central core of a high temperature, electrically conductive metal; and a coil of high temperature, electrically conductive metal wound thereabout, said coil being fastened to said core at least in part by mechanical interference. The mechanical interference can be achieved by keyways formed in the core surface. During winding, at least some of the turns of the coil enter the keyways providing a good,mechanical engagement of the coil with the core. The keyways can be formed by heating the core and compressing or forging areas with tools or the keyways can be formed by grinding or by any other suitable means.