The propagation velocity of a light-emitting wave-front is observed to be u p∼2×10+5 m/s before Townsend breakdown and u p∼5×10+6 m/s after Townsend breakdown along a discharge tube of inner diameter r o∼1.2 mm and length of 900 mm relevant to liquid crystal display television backlighting. Before Townsend breakdown, the origin of this wave is the ambipolar diffusion of plasma flux with the propagation speed u p∝D a/r o for the plasma bounded by the radius r o with the diffusion coefficient D a along the positive column. After Townsend breakdown, the light-emitting wave-front propagates with the electron plasma wave generated by the pulses of driving voltage. The electron plasma wave propagates such a long distance along the tube without damping due to the effect of localized plasma generation by electron impact ionization collisions. The propagation velocity is described by u p∼2u e 2/u d, which is larger than the electron thermal velocity u e as well as the electron drift velocity u d.

Using the ionization rates of each atom species in a mixture gas of Ne(95%) + Ar(5%) + Hg(∼mg), the minimum quantity of mercury in the glow plasma discharge of CCFLs and EEFLs for a large area LCD backlight, is calculated to be 0.05 ∼ 0.36 mg without considering the mercury consumption.

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The origin of optical emission in a fine‐tube fluorescent lamp is verified. The diffusion of plasma generated at a high voltage electrode, causes a radiation before Townsend discharge. At the normal glow, the propagation of electron plasma wave causes the light emission.

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