ABSTRACT
Glow discharge, particularly the location of luminous columns in the system, has been often explained by direct current (DC) glow discharge of an inert gas, e.g., argon [1-4], as shown in Figure 3.1. The major electrical field exists near the cathode (cathode region), and a secondary electron emitted from cathode surface gains energy in the electrical field while traveling toward the anode. In this acceleration of electron, the kinetic energy of the electron traveling in the cathode region is a function of the distance traveled from the cathode. When the electron gains enough kinetic energy to ionize the gas, the luminous gas phase recognized as negative glow develops. In the cathode dark space, electrons have not gained sufficient energy to cause the creation of luminous gas phase and thus the space remains dark. Beyond negative glow, it has been postulated that the positive charge density and the negative charge density are nearly equal and the gas phase maintains the electrical neutrality, which fits the criteria of plasma.
