基于激光诱导荧光法诊断大气压低温等离子体射流中OH自由基和O原子的时空分布  

Laser Induced Fluorescence Diagnostics of the Temporal and Spatial Distribution of OH Radicals and O Atom in a Low Temperature Plasma Jet at Atmospheric Pressure

作　　者：吴淑群[1,2] 董熙[1] 裴学凯[2] 岳远富 卢新培[2] Wu Shuqun;Dong Xi;Pei Xuekai;Yue Yuanfu;Lu Xinpei(College of Automation Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China;State Key Laboratory of Advanced Electromagentic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 China)

机构地区：[1]南京航空航天大学自动化学院,南京210016 [2]强电磁工程与新技术国家重点实验室(华中科技大学),武汉430074

出　　处：《电工技术学报》2017年第8期82-94,共13页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金(51077063;51607090);江苏省自然科学基金(BK20160796);校人才引进基金(90YAH15059)资助项目

摘　　要：由于传统辐射光谱法无法对大气压低温等离子体射流中OH自由基和O原子进行定量检测,本文利用自主研制的纳秒脉冲激励针筒型等离子体射流装置,基于单光子和双光子激光诱导荧光法分别对OH自由基和O原子的时空分布进行诊断。结果发现,OH自由基和O原子的寿命时间分别为1ms和3ms,远大于脉冲放电持续时间;采用拟合衰减曲线法,得到OH自由基的绝对密度为1012~1013cm-3;发现离喷嘴口越远,OH自由基和O原子密度越低。然而,即使距离喷嘴口数cm的地方,仍然存在大量的OH自由基和O原子;OH自由基和O原子的密度随激励频率和脉冲电压幅值的增加而升高,随H_2O含量和O_2含量的升高而出现先增大后减小的趋势。其中,当氦气中H_2O含量为0.012%时,OH自由基密度达到最大值。当氦气中O2含量为0.5%时,O原子密度达到最大值。本文研究为调控和优化低温等离子体射流中OH自由基和O原子密度提供重要科学依据。The method of traditional optical emission spectroscopy is not suitable for thequantitative measurements of the density of OH radical and O atom in low temperature plasma jets atatmospheric pressure.Thus,this paper applied the single-photon laser induced fluorescence(LIF)andtwo-photon absorption laser induced fluorescence(TALIF).The plasma jet with needle-cylinderelectrode structure was excited by nanosecond pulsed power supply.①OH radical and O atom in theplasma jet have a lifetime of1ms and3ms,respectively.They are much longer than the duration timeof pulse discharge.②By fitting the decay curve of fluorescence intensity of OH radical vs time,theabsolute density of OH radical is estimated to be1012～1013cm?3.③The densities of both activespecies decrease monotonically with the increase of the axial distance along the jet.However,it's surprising to observe that there are still a large amount of active species at even several cm far awayfrom the jet nozzle.④The increased excitation frequency and pulse voltage result in the increaseddensity of active species.Moreover,with the increase of the concentration of H2O impurities in heliumgas,OH radical density decreases after reaching a maximum value at2.7×1013cm?3for H2Oconcentration of120ppm.The behavior of O atom density shows the same tendency with the increaseof O2percentage in helium.The inflection point corresponding to the peak density of O atom occurs atthe O2percentage of0.5%.This study provides an important scientific basis for regulation andoptimization of the densities of OH radicals and O atom in low temperature plasma jets.

关 键 词：大气压低温等离子体射流 激光诱导荧光 活性粒子 等离子体医学 OH自由基 O原子 等离子体活性 

分 类 号：TM835.4[电气工程—高电压与绝缘技术]