氩气与氨气混合下的大气压介质阻挡放电(英文)

In this paper,the influence of ammonia admixture on argon discharge properties is investigated.Electrical measurements,as well as ten-nanoseconds-exposure photographs taken by an intensified charge-coupled device(ICCD)camera,are employed to confirm the existence of atmospheric pressure glow discharge(APGD)in Ar/NH3mixture.The breakdown voltage and transition voltage between APGD and filamentary discharge are studied at various ammonia concentrations.The results show that a small amount of NH3can lead to APGD due to the Penning ionization of NH3molecules by metastable argon,and the breakdown voltage increases with the growth in NH3concentrations owing to the electronegative feature of NH3.The optical emission spectrum of Ar/NH3APGD is analyzed.Besides,gas temperature is estimated at 327 K by the diagnoses of the OH(A-X)(0,0)band of the spectrum.     

施加电压和放电单元数对柱状阵列式介质阻挡放电特性的影响

低温等离子体富含高活性荷能、荷电粒子和自由基,并伴随着较强的短脉冲自生电场,在降解VOCs领域表现出很大的优势,且等离子体废气处理装置具有设备投资小、工艺简单、处理速度快、降解效率高等优点。文中基于介质阻挡放电原理,设计了一种循环水电极柱状阵列式等离子体反应器,搭建等离子体特性实验平台,研究不同电压幅值及不同放电单元数目下DBD的光、电特性,包括电压与电流波形、谐波情况、放电功率、放电图像、发射光谱等。研究发现:随着电压幅值的增大,电流脉冲数量明显增加,偶次谐波含量逐渐减弱至消失,放电更加均匀,特征谱线相对强度和氮分子振动温度均随之增大;且放电功率随电压的增大和放电单元数目的增多而增加,无功功率呈现负值。研究结果为优化等离子体反应器运行参数、提高实际大通量VOCs处理效果提供参考。     

大气压氦气与氩气等离子体射流形成机理的对比研究(英文)

To compare the formation mechanisms of He and Ar atmospheric pressure plasma jets(APPJs),an intensified charge-coupled device(ICCD)are utilized to observe the dynamic process of APPJ.The experimental results show that,He APPJ is first ignited,which is independent of the dielectric barrier discharge(DBD)between the two wrapped electrodes when the high voltage placed at the downstream.The intensity and APPJ length under positive discharge pulses are bigger than that under negative discharge pulses due to the space charge effect.The He APPJ is formed by the DBD development when the high-voltage electrode placed at the upstream side of tube.However,the plasma plume in Ar APPJ is formed by the propagation of DBD whatever the high-voltage electrode is arranged on upstream or downstream side of ground electrode.The difference in formation mechanism between He and Ar APPJs is mainly caused by the gas properties.Moreover,during the discharges,Ar tends to lead to thermal instability and electron Maxwellian instability.     

Study on the Property Evolution of Atmospheric Pressure Plasma Jets in Helium简

Nowadays atmospheric pressure plasma jets （APPJs） are being widely applied to many fields and have received growing interests from cold plasma community. A helium APPJ with co-axial double ring electrode configuration is driven by an AC high voltage power with an adjustable frequency of 1-60 kHz. Experiments are conducted for acquiring the electrical and optical properties of APPJ, including the discharge mode, current peak＇s phase and APPJ＇s length, etc. Moreover, the actions of Penning effect on APPJ are discussed by adding impurity nitrogen into highly pure helium. The results may contribute to further research and aPPlications of APPJs.     

大气压氦等离子体射流气体温度的光谱诊断(英文)

For atmospheric pressure plasma jets(APPJ),the gas temperature is essential for their applications.A spectral diagnosis of APPJ’s gas temperature is conducted in this work.The optical emission spectra of helium APPJ are captured by using an optical spectrometer system.Then,the grating secondary spectrum of OH(A2∑+(ν=0)→X2П(ν=0))are used to diagnose the gas temperature of plasmas because the spectrum has excellent resolution.Meanwhile,the vibrational temperatures are estimated by using the vibration sequence of N2band(SPS,the second positive system).On the basis of the method,some important conclusions were obtained.First,the spectral identifying indicates that the grating primary spectrum covers a whole wavelength range from 200 nm to 900 nm,and that the grating secondary spectrum overlaps with the primary spectrum from 400 nm to 900 nm.Second,the gas temperature(about 320 K)is close to the room temperature,while the vibrational temperature of the N2(SPS)is about 5 000 K.The trend of the two temperatures changing with the applied voltage is discussed in the end.     

基于OH基团二级光谱的氩大气压等离子体射流温度诊断

为了应用OH基团的二级光谱来诊断大气压等离子体射流(APPJs)的温度,首先采用线性场电极结构产生了氩大气压等离子体射流,利用增强型电荷耦合器件(ICCD)和三光栅光谱仪,拍摄了200～900nm波长范围内氩APPJs的光谱,并对光谱进行了辨认及分析,结果表明,除了氩原子的2p-1s(帕邢符号)跃迁谱线外,还存在一些分子基团的一级和二级光栅光谱,且其二级光谱的分辨率远高于一级光谱,其中OH(其相应跃迁为A2∑+→X2П)自由基尤为明显。然后选择OH(A2∑+→X2П)自由基的二级光谱诊断了OH自由基的转动温度(近似为等离子体射流的温度),并探讨了该温度随外施电压幅值、气体体积流量的变化,结果表明,在其他实验条件(如管径、电极间距和电极宽度)给定的情况下,氩APPJs的温度随外施电压幅值和气体体积流量的增大而都呈现先下降后上升的趋势,当外施电压幅值为10kV、气体体积流量为4L/min时,温度达到最小值348K。上述结果将为氩AP-PJs的参数调节及应用提供重要的帮助。     

Effect of Cold Plasma on Cell Viability and Collagen Synthesis in Cultured Murine Fibroblasts

An argon atmospheric pressure plasma jet was employed to treat L929 murine fibroblasts cultured in vitro.Experimental results showed that,compared with the control cells,the treatment of fibroblasts with 15 s of plasma led to a significant increase of cell viability and collagen synthesis,while the treatment of 25 s plasma resulted in a remarkable decrease.Exploration of related mechanisms suggested that cold plasma could up-regulate Cyclin D1 gene expression and down-regulate p27 gene expression at a low dose,while it could down-regulate Cyclin D1 expression and up-regulate p27 expression at a higher dose,thus altering the cell cycle progression,and then affecting cell viability and collagen synthesis of fibroblasts.     

大气压氩气介质阻挡放电等离子体特性变化的一维仿真

针对平行平板型大气压氩气介质阻挡放电(DBD),考虑等离子体中电子能量的贡献,建立了一维多粒子流体模型。通过对模型的求解,详细分析了频率为10 k Hz、幅值为1.5k V正弦电压驱动放电的变化过程,包括放电等离子体中各特性参数,如电子数密度、亚稳态氩原子数密度、放电间隙电位和电子温度等的时空变化过程。结果发现:放电模式从Townsend放电转变为稳定的辉光放电,在辉光放电阶段,放电间隙存在明显的阴极位降区、阴极辉区、Faraday暗区和正柱区等特征区域,且电子能量在不同的放电阶段有着不同的能量损失渠道。与此同时,探讨了固定驱动频率为10 k Hz,不同电压幅值的情况下,放电等离子体的粒子特性参数及放电模式。结果表明:电压从1.5 k V提高到3.5 k V时,最高电子温度、电子数密度、正离子数密度和亚稳态氩原子数密度均有所提高;简单分析了2.5 k V电压,不同频率下的电流波形和各种粒子在电流脉冲峰值处的空间分布,发现50 k Hz和100 k Hz的情况下,放电间隙阳极出现了阳极辉区;第一个电流脉冲峰值时刻,放电正柱区覆盖了Faraday暗区,而第二个宽电流脉冲时刻,法拉第暗区又重新出现。     

阻挡介质材料对低气压CO2介质阻挡放电转化特性的影响

介质阻挡放电(DBD)等离子体可产生大量荷能荷电粒子和活性自由基，具有高效、低耗、高可控程度、长使用寿命等优势，在CO₂资源化利用方面表现出良好的应用潜力。针对火星低气压高浓度的特殊CO₂氛围，为探究DBD中阻挡介质材料种类对CO₂转化效果的影响机理，利用kHz正弦电压驱动DBD,实验研究了不同阻挡介质材料对CO₂放电转化特性的影响。结果表明，阻挡介质依次为石英玻璃、环氧树脂、氮化铝、氧化铝、氧化锆(相对介电常数依次为4.7、6.6、9.8、10.2、37.1)时，放电产物中O₂的产量逐渐升高，其中氧化锆作为阻挡介质时的O₂产量远高于其他材料。结合数值仿真分析了阻挡介质相对介电常数和二次电子发射系数对CO₂转化效果的影响机理：固定二次电子发射系数，增大介质相对介电常数，气体间隙平均电场强度增大，放电产生的电子和CO⁺₂密度增大且维持在半峰值以上的时间增加，O₂主要生成反...     

大气压Ar-NH3混合气体氧化锆介质阻挡放电特性与产物分布

为了更好地调控等离子体氨制氢的效果，从等离子体自身入手，采用较高介电常数(37.1)的氧化锆阻挡介质，通过改变外施电压幅值和NH₃掺杂比例，研究大气压Ar-NH₃混合气体氛围放电的光电特性，利用光学发射光谱分析了放电产物的种类和代表性产物的分布规律。研究发现，随着外施电压的增加，等离子体沉积的功率逐渐增强，放电电流脉冲数目逐渐增加。较低NH₃比例下，亚稳态Ar原子和NH₃之间的彭宁反应使得放电图像表现为由汤森发展成辉光放电；而在较高NH₃比例下，NH₃对放电的淬灭作用逐渐增强，使得放电图像表现为细丝状。放电后缓慢降低电压时，较低NH₃比例下的辉光放电保持该放电模式熄灭，而较高NH₃比例下的丝状放电以单根放电柱熄灭。随着NH₃比例的增加，放电颜色由淡紫色转变为橙黄色，放电发射光强逐渐减弱，NH₃对电子的淬灭作用打破了电子产消的平衡模式，大量消耗了激发态氩原子和降低了NH产...