Effect of the Geometric of (Al) Hollow Cathode on Paschen Curves in Nitrogen

Abstract

Abstract In this paper, an experimental study of DC hollow cathode glow discharge plasma at different nitrogen pressures ranged from (0.065 to 0.75Torr) has been proposed. Investigated was carried out under the influence of the hollow cathode geometry such as diameter and depth of hollow cathode on the breakdown voltage of the nitrogen gas, the discharge system consists of two electrodes, the cathode forms various geometrical shapes and anode as a disc- shaped with diameter (8.8cm). The electrodes are enclosed in a large cylindrical glass chamber of pyrex filled with nitrogen gas. Three important physical parameters affecting the condition of the discharge are the gas pressure, constant inter-electrode distance and the cathode geometry. We used the hollow cathode with geometric shapes such as Cylindrical, conical, oppressive and variable dimensions. The cylindrical and conical shapes have inner diameters (3 & 6) cm and repressive shapes have inner diameter (1 & 2) cm. The breakdown voltage Vb is shown to depend on the product (p.d), for lower values of pressure, p or gap, d. This work represents the investigation of the dependence of the breakdown voltage on the gas pressure and on the distance between electrodes and the cathode geometry. The minimum value of breakdown voltage increases with increases gap d or increase the diameter of the hollow cathode with the length of the cavity is fixed.