Discharge Characteristics and Their Analysis of Alkaline-Metal Cold Cathodes

Abstract

In order to attain lower voltage operation of the glow-discharge devices such as a plasma display panel, the author intended to utilize the alkaline metals as the cathode material and made experimental and theoretical investigations of mainly normal cathode fall voltage V_n. First, in the experimental tubes of simple structure Cs, Rb, K, Na, and Li were introduced by vapor phase deposition and the cold-cathode voltage-current characteristics were measured for various noble gases leading to obtain the values of V_n. As a result it was revealed that V_n in these cathodes were lower by about half than that in the conventionaly used Ni cathode. Second, in order to get a guide to search cathode materials, Hagstrum's theory of ionic secondary electron emission coefficient γ_i in the metal was arranged and applied to various combinations of work function, Fermi energy of cathode materials, and ionization energy of the discharge gases resulting in the derivation of comparatively simple expressions and calculations of the γ_i. Moreover, by combining these results with the Ward's theory of cathode fall, theoretical values of V_n was obtained and compared with the above mentioned experimental values.