表面放电等离子体产生冲击波特性

采用压力传感器,分析XeF(CA)激光器高电压表面放电光泵浦方式不同位置、不同放电电压条件下冲击波特性。研究结果表明,表面放电等离子体膨胀产生的冲击波持续时间为ms量级,在冲击波过后伴随有相对较弱的压力波。随着充电电压增加,放电过程释放能量增多,冲击波峰值压强也变大,最大压强可达1 MPa,同时冲击波峰值延后,冲击波持续时间变长。     

分段表面放电沉积效率研究

利用一种结构紧凑的分段表面放电辐射源模块，详细研究了在不同电压、电容、气压实验条件下回路等效电阻、等效电感及放电能量沉积效率的变化规律，利用四分幅相机拍摄获得了不同实验条件下的放电等离子体通道图像，分析讨论了放电等离子体运动对放电能量沉积效率的影响，提出了提高能量放电沉积效率的有效途径。     

分段表面放电沉积效率研究

 利用一种结构紧凑的分段表面放电辐射源模块，详细研究了在不同电压、电容、气压实验条件下回路等效电阻、等效电感及放电能量沉积效率的变化规律，利用四分幅相机拍摄获得了不同实验条件下的放电等离子体通道图像，分析讨论了放电等离子体运动对放电能量沉积效率的影响，提出了提高能量放电沉积效率的有效途径。     

分段表面放电沉积效率研究

利用一种结构紧凑的分段表面放电辐射源模块,详细研究了在不同电压、电容、气压实验条件下回路等效电阻、等效电感及放电能量沉积效率的变化规律,利用四分幅相机拍摄获得了不同实验条件下的放电等离子体通道图像,分析讨论了放电等离子体运动对放电能量沉积效率的影响,提出了提高能量放电沉积效率的有效途径。     

空气中激光等离子体冲击波的传输特性研究

根据球形对称冲击波在自由空间中传播的约束条件,提出了空气中激光等离子体冲击波在中远场的传播公式.并用探针式超声换能器实测了能量为10-110mJ、脉宽为15ns、波长为106μm的Nd∶YAG激光作用于铝靶表面产生的等离子体空气冲击波,用此公式计算的结果与实验数据符合得很好 关键词：     

横向表面放电光泵浦源特性研究

 介绍了一种用以泵浦XeF(C-A)激光的横向表面放电辐射源,比较详细地研究了这种泵浦源的放电击穿特性、放电电流与充电电压及不同气体介质的关系、表面放电均匀性以及不同气体成分对表面放电辐射特性的影响。得到了放电击穿时间、放电峰值电流随充电电压、不同气体介质变化的曲线;分析了提高放电均匀性的途径,在电极长50cm、间距6cm、充电电压25kV条件下获得了均匀放电。获得了各种实验条件下放电辐射的光谱曲线;通过对辐射光谱的分析,研究了有利于光解离XeF₂的最佳实验条件,当p_Ar:p_N2=1:1时,放电在远紫外波段产生的辐射最强。     

激光感应等离子体冲击波碎石

文章对激光感应等离子体冲击波碎石技术的物理机理、发展现状及未来趋势做了综合性评述，并结合作者的实验研究对激光碎石中存在的重要技术问题进行了探讨，同时提出了一些可能的解决办法．     

横向表面放电光泵浦源特性研究

介绍了一种用以泵浦XeF(C-A)激光的横向表面放电辐射源,比较详细地研究了这种泵浦源的放电击穿特性、放电电流与充电电压及不同气体介质的关系、表面放电均匀性以及不同气体成分对表面放电辐射特性的影响。得到了放电击穿时间、放电峰值电流随充电电压、不同气体介质变化的曲线;分析了提高放电均匀性的途径,在电极长50cm、间距6cm、充电电压25kV条件下获得了均匀放电。获得了各种实验条件下放电辐射的光谱曲线;通过对辐射光谱的分析,研究了有利于光解离XeF2的最佳实验条件,当pAr:pN2=1:1时,放电在远紫外波段产生的辐射最强。     

大气压等离子体针产生空气均匀放电特性研究

大气压空气放电由于脱离了真空装置,易于实现流水线生产,因而在工业上具有广泛的应用. 采用等离子体针装置在空气中产生了稳定的大气压均匀放电. 利用光谱法对等离子体的相关参数进行了空间分辨率测量,并通过光学方法对放电机理进行了研究. 结果表明,等离子体针产生的放电存在电晕放电和等离子体羽放电两种模式. 在稳定的等离子体羽放电模式中,发光分为强光区和弱光区. 弱光区放电的发展速度远大于强光区的发展速度,电子能量和电子密度均是弱光区比强光区大. 对均匀放电的气体温度和振动温度的研究表明,强光区放电遵循汤生击穿机理而弱光区为流光放电. 这些结果对大气压空气放电的工业应用具有重要意义. 关键词： 大气压均匀放电 等离子体针 发射光谱 放电机理     

Investigation on the shockwave induced by surface arc plasma in quiescent air

The shockwave induced by surface direct-current （DC） arc discharge is investigated both experimentally and numer- ically. In the experiment, the shockwave generated by rapid gas heating is clearly observed from Schlieren images. The peak velocity of the shockwave is measured to be over 410 m/s; during its upright movement, it gradually falls to about 340 m/s; no remarkable difference is seen after changing the discharge voltage and the pulse frequency. In the modeling of the arc plasma, the arc domain is not simulated as a boundary condition with fixed temperature or pressure, but a source term with a time-varying input power density, which could better reflect the influence of the heating process. It is found that with a reference power density of 2.8× 1012 W/m2, the calculated peak velocity is higher than the measured one, but they quickly （in 30 Its） become agreed with each other. The peak velocity also rises while increasing the power density, the maximum velocity acquired in the simulation is over 468 m/s, which is expected to be effective for high speed flow control.     

Investigation on surface properties of TiO2 films modified by DC glow discharge plasma

In the present work, TiO₂ films deposited on polyethylene terephthalate substrates by dip coating technique were subsequently treated by DC glow discharge plasma as a function of discharge potential. Hydrophilicity of these TiO₂ film surfaces was analyzed by contact angle measurements. Atomic force microscopy (AFM) revealed changes in surface morphology of the plasma treated TiO₂ films. Modifications in structural and chemical composition of the TiO₂ films were detected by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The blood compatibility of TiO₂ films was studied by in vitro investigation which includes thrombus formation and whole blood clotting time analysis (WBCT). It was found that the plasma treatment results in blood compatibility enhancement attributed to the structural, chemical and morphological properties of the modified film surfaces.     

亚微秒脉冲表面介质阻挡放电等离子体诱导连续漩涡的研究

使用粒子激光图像测速技术对亚微秒脉冲激励表面介质阻挡放电激励器连续产生诱导漩涡进行了实验研究, 给出了包含脉冲重复频率和漩涡频率的双频率激励模式的具体形式. 实验过程中出现了原发型与继发型两类示踪粒子空白区, 前者由放电释热的微爆炸作用造成, 使得诱导流动远离壁面, 能够减小壁面摩擦阻力的作用; 以暴露电极左侧继发型空白区被完全吹除作为重复启动激励的临界点. 为提高控制效果应采用尽可能高的脉冲重复频率, 漩涡时间内脉冲数量应大于10, 最大诱导速度随脉冲数量增大而增大, 但动量传递效率降低. 使用亚微秒脉冲激励具备释热、体积力两种作用机理. 关键词： 双频率亚微秒脉冲 表面介质阻挡放电 连续漩涡     

Investigation of the amplifying properties of a krypton gas discharge plasma

The characteristics of a gas discharge in krypton (at a pressure of several atmospheres), used as a medium for lasers based on excimer transitions in the VUV region, have been calculated. It is shown that, to achieve the threshold values of excimer concentration, a high preionization level and the shape of the applied voltage pulse are important factors. It has been found that the shape of the excimer emission pulse is determined, to a large extent, by stepwise processes with the participation of electrons and by the relaxation time of the electron energy.     

Effects of air dielectric barrier discharge plasma treatment time on surface properties of PBO fiber

In this paper, the effects of air dielectric barrier discharge (DBD) plasma treatment time on surface properties of poly(p-phenylene benzobisoxazole) (PBO) fiber were investigated. The surface characteristics of PBO fiber before and after the plasma treatments were analyzed by dynamic contact angle (DCA) analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). DCA measurements indicated that the surface wettability of PBO fiber was improved significantly by increasing the fiber surface free energy via air DBD plasma treatments. The results were confirmed by the improvement of adhesion of a kind of thermoplastic resin to PBO fiber which was observed by SEM, showing that more resin was adhering evenly to the fiber surface. AFM measurement revealed that the surface topography of PBO fiber became more complicated and the surface roughness was greatly enhanced after the plasma treatments, and XPS analysis showed that some new polar groups (e.g. OCO) were introduced on plasma treated PBO fiber surface. The results of this study also showed that the surface properties of PBO fiber changed with the elongation of plasma treatment time.     

The influence of electrode gap width on plasma properties of diffuse coplanar surface barrier discharge in nitrogen

In this work we have studied the influence of electrode gap width (inter-electrode distance) on plasma properties of the diffuse coplanar surface barrier discharge. The outer conditions and discharge configuration can substantially influence properties of the discharge. Better understanding of these effects can lead to optimization of the discharge parameters for industrial applications. In this work the discharge was operated in nitrogen at atmospheric pressure. The electrode gap width was varied in the range from 0.6 to 2.2 mm. The input voltage, electrode temperature and gas flow was kept constant for all cases. Plasma parameters were studied by the means of time and space resolved optical emission spectroscopy and oscilloscopic measurements. These measurements gave us time and space distribution of discharge luminosity (e.g. intensities of second positive and first negative systems of nitrogen) and 1D-spatial profiles of rotational and vibrational temperature of nitrogen.     

Electrode surface erosion in a high-frequency discharge plasma

The surface erosion of electrodes made of different materials in the plasma of a high-frequency discharge, which is used for pumping ion lasers at a frequency of 10 MHz, is investigated. It is found that the erosion is due to blistering. The effect of the electrode temperature and material, as well as of the gas type, on the erosion evolution under typical operating conditions of a gas discharge tube is studied. The concentration of blistering products (dust particles) in the discharge is estimated in the framework of geometrical optics. Ways to prevent blistering in the discharge under such conditions are suggested.     

Modification of surface properties of polypropylene (PP) film using DC glow discharge air plasma

The industrial use of polypropylene (PP) films is limited because of undesirable properties such as poor adhesion and printability. In the present study, a DC glow discharge plasma has been used to improve the surface properties of PP films and make it useful for technical applications. The change in hydrophilicity of modified PP film surface was investigated by contact angle (CA) and surface energy measurements as a function of exposure time. In addition, plasma-treated PP films have been subjected to an ageing process to determine the durability of the plasma treatment. Changes in morphological and chemical composition of PP films were analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The improvement in adhesion was studied by measuring T-peel and lap shear strength. The results show that the surface hydrophilicity has been improved due to the increase in the roughness and the introduction of oxygen-containing polar groups. The AFM observation on PP film shows that the roughness of the surface increased due to plasma treatment. Analysis of chemical binding states and surface chemical composition by XPS showed an increase in the formation of polar functional groups and the concentration of oxygen content on the plasma-processed PP film surfaces. T-peel and lap shear test for adhesion strength measurement showed that the adhesion strength of the plasma-modified PP films increased compared with untreated films surface.     

Thermal and induced flow characteristics of radio frequency surface dielectric barrier discharge plasma actuation at atmospheric pressure

Thermal and induced flow velocity characteristics of radio frequency(RF) surface dielectric barrier discharge(SDBD)plasma actuation are experimentally investigated in this paper. The spatial and temporal distributions of the dielectric surface temperature are measured with the infrared thermography at atmospheric pressure. In the spanwise direction, the highest dielectric surface temperature is acquired at the center of the high voltage electrode, while it reduces gradually along the chordwise direction. The maximum temperature of the dielectric surface raises rapidly once discharge begins.After several seconds(typically 100 s), the temperature reaches equilibrium among the actuator's surface, plasma, and surrounding air. The maximum dielectric surface temperature is higher than that powered by an AC power supply in dozens of k Hz. Influences of the duty cycle and the input frequency on the thermal characteristics are analyzed. When the duty cycle increases, the maximum dielectric surface temperature increases linearly. However, the maximum dielectric surface temperature increases nonlinearly when the input frequency varies from 0.47 MHz to 1.61 MHz. The induced flow velocity of the RF SDBD actuator is 0.25 m/s.