【作者】 郭卿超；

【导师】 王德真； 张家良；

【作者基本信息】 大连理工大学 ， 等离子体物理， 2010， 硕士

【摘要】 本文探索了一种平板式小孔电极的放电装置,采用电学测量,光学诊断等方法对射频容性氩等离子体进行了研究。在一定的条件下,特别放电气压条件适当时,两种放电模式可以共存,其物理原因是两种放电模式的维持电压在不同气压下相对大小不同。大气压下,α模式的维持电压高于γ模式,导致一旦放电电压超过γ模式的维持电压,放电将完全转变为γ模式,形成局部丝状微弧放电。对于氩气的大气压射频放电特性实验研究发现：可以实现两个模式在大气压放电条件下的共存。本文中,我们首先实现了大气压条件下的氩气流动体系中容性射频放电的α和γ两个模式及其转变与共存,对放电形态进行了观察,利用伏安特性进行分析,确认了两种模式的产生和共存。由于放电处于开放大气环境中,放电发射光谱中清晰地存在N2 C3∏u→B3∏g跃迁产生的第二正带和OH自由基A2∑→X2∏跃迁的(0,0)带光谱。为了获得放电区域的宏观温度,针对氮的第二正带(0,1),(1,2)两个谱带,自编了拟合程序,用温度拟合方法获得了氮分子的转动温度和振动温度,研究了转动温度随放电功率的变化趋势,得到了温度突变与放电模式转变的相关性。利用Lifbase的发射光谱模拟功能,进行了OH自由基A2∑→X2∏(0,0)带光谱的模拟,通过与实验光谱对比,得到了与N2光谱拟合结果相符的OH转动温度,以及相似的随放电功率的变化趋势,这说明放电空间内的中性物种达到了热平衡状态。放电模式转变对应的转动温度变化趋势根据放电伏安特性变化得到确认,并且与放电形态的照片符合。用波尔兹曼曲线的方法测得了氩原子的激发温度,而且激发温度并不随功率的改变有明显的改变,约为2800K,并估算了电子温度。探索了用红外热像仪的测量气体温度的方法,对红外热像仪的测量原理做了简要的介绍,并用红外热像仪的方法测量了放电的宏观温度,与光谱测得的转动温度相吻合。更多还原

【Abstract】 In this paper, the characteristics of RF argon capacitive discharge at atmospheric pressure with the structure of fiat-plate electrodes are investigated by electrical measurements and optical diagnostics.The existence of two discharge modes named a and y mode were found under specific conditions, the holding voltage of two discharge modes are different in different gas pressure. The holding voltage of a mode is higher than the holding voltage of y mode in atmospheric pressure. So a mode to y mode transition at higher voltage will be investigated. The mode transition and coexistence were found in atmospheric pressure argon RF capacitive discharge. In this paper, according to the change of Current-voltage characteristics, the mode transition was affirmed, and answered to the photograph of discharge.The emission spectra of N2 (C3Πu→B3Πg) and OH (A2Σ→X2Π) were observed due to the atmosphere surrounding. By use of a program compiled by the authors for the nitrogen’s second positive band simulation, comparison between the experimental and simulated spectra of band (0,1), (1,2) was used to determine the rotational and vibrational temperature of N2. The trend of vibrational and rotational temperature with discharge power was studied to observe the temperature jump corresponding to the discharge mode transition. Utilizing a well-known software named Lifbase, the simulated spectra of OH (A-X) (0,0) was calculated to obtain the rotational temperature of OH by comparing with the experimental OH (A-X) (0, 0) band. The resultant rotational temperature of OH is well consistent with the result of nitrogen’s second positive band, which shows that the neutral species are at thermal equilibrium in the space of discharge. Excited temperature was about 2800K attained by Boltzmann equation, and excited temperature not evidently changes versus the change of power. Electron temperature was estimated on the basis of excited temperature. The theory of infrared thermal imager was introduced. Gas temperature was measured using infrared thermal image, and answered to rotational temperature.更多还原