大气压Ar射频容性放电模式转变的温度表征

在大气压条件下Ar气流中实现了容性射频放电α和γ两种模式及其转变与共存.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 N₂C³Π_u→Β³Π_g跃迁产生的第二正带和OH自由基 Α²Σ→Χ²Π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Α²Σ→Χ²Π(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.根据放电伏安特性变化,放电模式转变对应的转动温度变化趋势得到确认,并且与放电形态的照片符合. 关键词： 大气压等离子体 放电模式 转动温度

Characterization on the temperature of radio frequency argon capacitive discharge mode transition at atmospheric pressure

The mode transition and coexistence were investigated in atmospheric pressure argon radio frequency capacitive discharge. 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) and (1, 2) was used to determine the rotational and vibrational temperatures of N₂. The trends of vibrational and rotational temperatures with discharge power were 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 calculated 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. According to the current-voltage characteristic, the temperature jump corresponding to the discharge mode transition was confirmed in accordance with the photograph of discharge.