以氦氣為主的平板型常壓電漿束特性之實驗研究

Abstract

本研究設計一個新的Power與Ground電極為上下形式的平板型電極設備，操作於常壓的介電質電漿源(DBD)。此電漿源以脈衝式交流電源驅動，操作頻率介於20-60 kHz，以氦氣為主要電漿氣體。實驗不同參數包括 : 介電質材料、介電質材料距離、流量、頻率、功率與兩電極間距離。實驗結果發現，使用石英、兩平行板介電質距離 0.5 mm、流量30 slm、頻率60 kHz與兩電極距離10 mm時可以產生一均勻的氦氣電漿束。當在放電區間中增加一浮動電極時，電漿放電電流從40 mA增加至120 mA，此電極組合即可以成功使氬氣放電，形成一穩定電漿源。在不添加氧氣的純氦氣(99.99%)放電情形下，經由OES量測光譜發現N2 second position (337.1nm) 、NO-γ(180-260 nm peak lines) 、 放光反應 。另O 原子以777 nm為主，在應用上相當有用處。也從加入不同氧氣的比例，發現於小比例0.03-0.07% O2產生較大電漿電流與均勻的電漿，並經由OES的量測此時會增加電漿強度。本研究成功建立氦氣電漿於此電極設計，對各種參數影響的資料庫與了解氦氣與加氧的電漿反應機制。

In this thesis, a new planar atmospheric-pressure dielectric barrier discharge (DBD) with and without a floating electrode is developed and characterized experimentally. Helium is used as the major discharge gas and is driven by distorted sinusoidal voltages operating in the range of 20-60 kHz. Parametric studies without a floating electrode are conducted considering the variations of dielectric material, distance between dielectric materials, gas flow rate, distance of power and ground electrodes, frequency and power output of power source. A uniform gas discharge jet is obtained with the following operating conditions: quartz dielectric plates, dielectric gap distance of 0.5 mm, flow rate of 30 slm, frequency of 60 kHz and distance of power and ground electrode of 10 mm. By adding a floating electrode inside the discharge gap, discharge current increases dramatically from 40 mA to 120 mA. In this optimal condition a stable discharge jet is established using argon gas, which is otherwise extinguished. By using OES measurements in the pure helium case (ca. 99.99%), we have found that abundant N2 second position (337.1nm) and NO-γ(180-260 nm peak lines) exist in the post-discharge region. In addition, we have also found oxygen atom (777 nm), which is useful in applications. By adding a small quantity of oxygen (0.03%-0.07%) into the helium discharge, the optical emissions at all wavelengths enhance as compared to the pure helium case.