GB631383A - Improvements in or relating to ionic discharge tubes - Google Patents

Abstract

631,383. Metal-vapour discharge apparatus. PHILIPS LAMPS, Ltd. Nov. 28, 1946, No. 35322. Convention date, July 15, 1943. [Class 39 (i)] An ion discharge tube has a liquid cathode 2, Fig. 1, in which is immersed a capacitative ignition anode 6, and the glass wall of the tube has an external coating 11 of graphite which is electrically connected to the cathode and which functions to raise the lowest voltage at which spontaneous ignition can occur. The ignition anode is a quartz tube 6 partly filled with mercury, the tube 6 being sealed to a glass tube 8 through a graded seal 7. Caps 4, 5 are of chrome-iron and the anode 3 is also of mercury. The device may have a filling of Argon at 0.01 mm. or 0.02 mm. In a somewhat similar arrangement, Fig. 3 (not shown), the anode and cathode are each provided with a capacitative starting electrode, and two external graphite coatings are provided, one electrically connected to the cathode and the other to the anode. An insulating shield is disposed between the two graphite coatings. In another embodiment, Fig. 2, the anode 3 is of graphite or carbonised iron and is surrounded by a metal gauze screen 17 mounted on a ceramic tube 14. The graphite coating 11 is electrically connected to the cathode through a high resistance 13.