Study of PDP Micro-Discharges Using Laser Thomson Scattering

在本研究中，激光汤姆逊散射(LTS)方法被发展为一种等离子体显示板(PDP)类微放电等离子体的诊断方法，并用该方法研究了等离子体的详细结构。主要研究成果如下：(1)研制了一种宽度为2 mm的模拟PDP维持电极的新型电极基板。同时，通过控制光束发散角，将激光光斑尺寸调整到50μm以下。这使我们能够在距离电极表面60μm的地方检测到LTS信号。在此基础上，成功地测量了微放电等离子体的电子密度Ne和电子温度Te的二维分布。(2)用LTS方法测量了PDP类放电条纹等离子体的Ne和Te分布。测量了Ne/Ar(10%)混合气体在200Torr压力下产生的放电。在电极衬底的阳极侧观察到明显的Ne调制，这与ICCD相机测量的总积分发射图像一致。此外，还观察到了Te的调制，并发现它与Ne的调制是异相的。(3)以532 nm激光的二次谐波为光源的可见光LTS系统不适用于Ne/Xe混合气体的放电，因为Xe原子被532 nm光的多光子吸收电离。为了避免这种微扰现象，新研制了以基波输出的1064 nm激光为光源的红外激光测温系统。我们将红外LTS应用于Ne/Xe混合气体中的放电，证明了放电等离子体不受干扰。Ne/Xe等离子体的N_e和T_e的测量结果与在相似放电条件下产生的Ne/Ar等离子体的测量结果相似。

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.