Plasma description with optical signal propagation along the fine tube of positive column discharge

When the optical signals are observed along the fine tubes of cold cathode and external electrode fluorescent lamps for the light sources of LCD-TVs, the light signal is measured and found to be propagated from the high voltage to the ground sided. The phenomenon of the light propagation has been explained with the electron drift along the tube in Cho et al. (2007). In Cho et al. (2008), this has been analyzed as the propagation of electron plasma wave along the tube. In both cases, the plasma parameters of electron temperature and density have been verified as kT_e~1 eV and n_e~10¹⁷ m^-3. However, they leave room for doubt. In the analysis of electron drift, the electron drift velocity has been measured as ~10⁵ m/s which is unreasonably higher than the conventional glow discharge plasma of ~10⁴ m/s. In the electron plasma wave propagation, it has still some doubt that the propagation distance along the positive column plasma can be as far as ~10 centimeter or ~1 meter since the electron plasma wave damping coefficient is too high for the electron wave to propagate such a long distance. Further more, it might be impossible that the electron energy can be transferred to the positive column plasma through the propagation of electron plasma wave. In this study the effects of plasma diffusion as well as the influence of electron plasma propagation on the optical signal propagation are investigated. However, the analysis of optical observation results provides the verification of plasma generation mechanism as well as the plasma properties in a positive column of a fine tube fluorescent lamp.