Study of PDP Micro-Discharges Using Laser Thomson Scattering

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In this research, the laser Thomson scattering(LTS) method has been developed as a diagnostic method of plasma display panel(PDP)-like micro-discharge plasmas and detailed structure of the plasmas have been investigated by the method. Results are outlined as follows.(1)A new electrode substrate which simulated the sustain electrodes of PDP and had a width of 2 mm was developed. Also, the laser spot size was adjusted to be below 50 μm by controlling the beam divergence of the laser. These allowed us to detect LTS signals at points as close as 60 μm from the electrode surface. Then, two-dimensional profiles of electron density n_e and electron temperature T_e of micro-discharge plasmas were successfully measured.(2)The LTS method was used to measure n_e and T_e profiles of a striated plasmas in the PDP like discharge. Measurements were performed for the discharge produced in the gas mixture of Ne/Ar (10%) at a pressure of 200 Torr. A modulation in ne was clearly observed on the anode side of the electrode substrate, which agreed with the total integrated emission images measured by an ICCD camera. Also, a modulation in T_e was observed and it was found to be out of phase from the modulation in n_e.(3)The visible LTS system using the second harmonics of the YAG laser (wavelength 532 nm) as the light source was found to be not applicable to discharges in Ne/Xe gas mixtures because Xe atoms were ionized by the multi-photon absorption of the 532nm light. In order to avoid such perturbation phenomenon, the infrared LTS system using the fundamental output of the YAG laser (wavelength 1064 nm) as the light source was newly developed. We applied the infrared LTS to discharges in a Ne/Xe gas mixture and proved that the discharge plasmas were not disturbed. Also, we showed that the measured profiles of n_e and T_e of the Ne/Xe plasmas were similar to those observed for the Ne/Ar plasmas produced under the similar discharge conditions.