How plasma produce the fluorescent?? Is it true when the electron that suppose to ionize the gas which have less energy to cause ionization hit an orbital electron, the orbital electron will just excited to certain energy and back to ground state and emitting the glow discharge or fluorescent? If its true, the glow discharge doesn't means the gas is fully ionized right? if we want total volume of ionized gas, the glow discharge must not appear isn't it?? so what function the glow discharge do anyway?? for me it's just a color... i'm kinda confused right now, help... help..

You can get the light from excitation and the resulting de-excitation, but that transition also happens when the electron recombines with the ion. There will generally be a cascade of photons as the electron jumps down levels.

"but that transition also happens when the electron recombines with the ion" - this point give me a hint to find the answer, actually i do sputtering for thin film fabrication and still a newbie, i know plasma is ionized gas and usually indicated by the glow discharge, but i want to measure how much the glow discharge influence the process. May be from it's intensity or brightness