The Effect of Argon Pressure on the Life of Fluorescent Lamp

Usually the life of fluorescent lamp depends upon the pressure of sealed-in argon gas. In this paper the author treated of this problem, and first investigated the relation between the argon gas pressure and the life measured by the filament voltage method reported in the previous paper.(Jour. of Ilium. Eng Inst of Japan, 37, Oct. 1952). As the result, it was found that the consumption velocity of the cathode material increased more rapidly and consequently the life became extremely shorter, as the argon gas pressure decreased below about 3 mmHg.Generally speaking, the sputtering and the evaporation at the electrode are considered as the ca use of its consumption in the discharge tube, the author researched which phenomenon was more effe ctive in the consumption, and obtained the result that in fluorescent lamp the consumption did not depend upon the sputtering, but the evaporation from the cathode spot. Moreover it was cleared up quantitatively that the effect of the argon gas pressure on the life of fluorescent lamp was due to the diffusion of evaporated material in the argon gas.