AC Microplasma Device With a Cylindrical Hollow Electrode for Improving Luminous Efficacy

In this paper, a device utilizing the hollow cathode discharge is demonstrated to diagnose the possibility of improving luminous efficacy of a microplasma device. A series of experiments is conducted by measuring luminous efficacy, which is an important factor in display devices, in accordance with specifications of the cylindrical hollow and gas pressure. The proposed structure has two electrodes, and one of them contained a cylindrical hole and is called a hollow electrode. The hollow electrode works as either a cathode or an anode alternately due to the ac operating conditions. When the hollow electrode operated as a cathode, the luminous efficacy is higher than that of the anode case, and this tendency is observed consistently throughout all experiments. Moreover, from the measurement results on the tendency of luminous efficacy in terms of hole specifications, different aspects of luminous efficacy are obtained, depending on whether the variation is in the diameter or in the depth. In case of the diameter, the luminous efficacy is improved when
p
middot
D
(i.e., the product of the gas pressure and the diameter of the cylindrical hole) is less than one Torr ldr cm. In the case of the depth, the maximum value of luminous efficacy exists at the certain
p
middot
d
(i.e., the product of the gas pressure and the depth of the cylindrical hole).