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The microdischarge process and the vacuum ultraviolet (VUV) emission properties of dielectric-barrier-discharge-type flat fluorescent lamps (FFLs) are investigated by shooting the spatiotemporally resolved images of a microdischarge in an FFL filled with Ne-Xe (10%) gas mixture of 85 kPa with a high-speed intensified charge-coupled device camera and by measuring the VUV emission spectra at various gas pressures and driving parameters with a vacuum monochromator and a photomultiplier tube. It was found that a microdischarge was generated at a protrusion on the cathode at first, diffused to the anode side afterward, and exhibited a uniform glow discharge pattern. The measured results of the VUV spectra show that, as the total gas pressure increases, the 147-nm resonance emission gradually decreases, while the continuum emission centered at 173 nm rapidly increases, which cause both of the intensity and the efficiency of the VUV emission to increase. As the driving voltage amplitude increases, there exists a maximum VUV emission efficiency value. At a total gas pressure of 70 kPa, as the driving pulse frequency increases from 50 to 130 kHz, the spectral intensities of the VUV emission initially increase and then gradually tend to saturate at 90 kHz.
Date of Publication: Nov. 2011