DISCHARGE TUBE

摘要

A discharge tube having a long lifetime in which a cup-like electrode can be formed easily. The discharge tube (1) comprises an inner tube(12) secured to the inner side of the side wall part (11a) of the electrode (11), wherein the inner tube(12) is composed of a metal having a sputtering rate lower than that of the electrode (11). According to the arrangement, a cup-like electrode (11) can be formed easily of a metallic material having a relatively high sputtering rate and exhibiting good machinability, and consumption of the electrode (11) due to sputtering can be suppressed because the inner tube (12) formed tubularly of a metal having a low sputtering rate is disposed on the inner side of the cup-like electrode (11). Since consumption of mercury contained in the discharge gas encapsulated in a glass tube (2) can be suppressed, a fluorescent discharge lamp having a long lifetime can be realized.