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1.
Electrode materials and shapes affected the discharge modes. Meanwhile, the discharge has influence upon electrode surface. In order to study the effect of discharge on semiconductor electrode, the experiments were carried out using single crystal Si wafer as high voltage electrode of atmospheric pressure dielectric barrier discharge in air. The effects of dielectric barrier discharge on Si electrode surface are analyzed by means of field emission scanning electron microscope (FESEM) and X-ray photoelectron spectroscopy (XPS). The results show that surface roughness and oxidation increase with discharge time, while surface nitridation is not observed on Si electrode surface. It is different from Cu electrode. The difference is due to different chemical reactions between electrode surface and air plasma but could also be ascribed to the different analysis techniques used. 相似文献
2.
在介质阻挡放电体系中产生辉光放电可以有效的提高放电体系产生高能电子的性能, 为等离子体化学反应提供更加丰富的活性粒子.本文对针-板介质阻挡放电体系下的放电模式进行了研究,实验发现放电正负半周期表现出不同的放电模式, 激励电压为3 kV时放电正负半周期分别为微流注放电和电晕放电(或者Trichel脉冲放电),激励电压为6 kV时放电正负半周期分别为微流注放电和微辉光放电.微辉光放电形貌具有与典型辉光放电相同的分层次放电结构, 分析了激励电压6 kV时的放电过程,认为足够强的阴极电场强度和裸露针状电极形成的有效的二次电子发射过程是形成微辉光放电的主要因素,绝缘介质层的存在避免了微辉光放电向弧光放电过渡. 相似文献
3.
Barrier dielectric is an important part of atmospheric pressure dielectric barrier discharge (AP-DBD), which partly affects discharge characteristics. Conversely, discharge plasma also has influence on dielectric surface properties. To investigate this influence, some experiments were carried out on a home-built AP-DBD system with glass plate as barrier dielectric. Surface wettability was evaluated by water contact angles on a drop shape analysis system. The morphologies and chemical compositions of the glass sample surfaces were observed by field-emission scanning electron microscope (FESEM) and energy dispersive X-ray spectroscopy (EDS) attached to FESEM. The results show that water contact angles decrease as discharge energy increases, micro-discharge etching zones are formed into glass surface and different from the control glass in surface micro-structure and chemical compositions. 相似文献
4.
The discharge initiation mechanism of nanosecond dielectric barrier discharges in open air has been clarified with time-dependent measurement of the discharge electric field by electric-field-induced coherent Raman scattering and optical emission. Our experimental observations have revealed that, in the prebreakdown phase of a nanosecond dielectric barrier discharge, the externally applied fast-rising electric field is strongly enhanced near the cathode due to large accumulation of space charge, which then strongly enhances ionization near the cathode. Once a sufficiently large number of ionizations take place, the location of peak ionization forms a front and propagates toward the cathode with strong optical emission, which establishes the discharge. This process is essentially different from the well-known Townsend mechanism for slower discharges. 相似文献
5.
利用静电场模型对线筒式介质阻挡放电电场强度进行了计算,并对电子平均动能进行了估算。通过对单双介质阻挡放电(DBD)的对比,发现在相同的放电条件下,双介质DBD产生的电场强度和电子平均动能比单介质DBD的要大。这就很好地解释了在相同的放电参数下,甲苯的降解效率在双介质DBD中要比单介质DBD中大。 相似文献
6.
��������ӷ��� 《核聚变与等离子体物理》2017,37(4):399-403
The electric field strength and electron mean kinetic energy in co-axial dielectric barrier discharge (DBD) were estimated based on static electric filed model. Through the comparison of the single dielectric layer DBD with the double dielectric layer DBD, it was found the electric field strength and electron mean kinetic energy in double dielectric layer DBD are greater than that in the single dielectric layer DBD under the same electrode configuration and discharge conditions. The calculation results can successfully applied to explain the toluene degradation efficiency in double dielectric layer DBD is larger than that in the single dielectric layer DBD under the same discharge parameters. 相似文献
7.
Numerical studies of atmospheric pressure glow discharge controlled by a dielectric barrier between two coaxial electrodes 总被引:1,自引:0,他引:1 下载免费PDF全文
The glow discharge in pure helium at atmospheric pressure, controlled
by a dielectric barrier between coaxial electrodes, is investigated
based on a one-dimensional self-consistent fluid model. By solving
the continuity equations for electrons, ions, and excited atoms, with
the current conservation equation and the electric field profile, the
time evolution of the discharge current, gas voltage and the surface
density of charged particles on the dielectric barrier are
calculated. The simulation results show that the peak values of the
discharge current, gas voltage and electric field in the first half
period are asymmetric to the second half. When the current reaches
its positive or negative maximum, the electric field profile, and the
electron and ion densities represent similar properties to the
typical glow discharge at low pressures. Obviously there exist a
cathode fall, a negative glow region, and a positive column. Effects
of the barrier position in between the two coaxial electrodes and the
discharge gap width on discharge current characteristics are also
analysed. The result indicates that, in the case when the dielectric
covering the outer electrode only, the gas is punctured earlier
during the former half period and later during the latter half period
than other cases, also the current peak value is higher, and the
difference of pulse width between the two half periods is more
obvious. On reducing the gap width, the multiple current pulse
discharge happens. 相似文献
8.
采用稍不平行电极进行大气压He气介质阻挡多脉冲辉光放电实验,通过增强电子耦合器件相机短时曝光照片,研究大气压多脉冲辉光放电在不同时刻的放电模式.通过气隙放电电流、表面电荷计算,理论分析了表面电荷、空间电荷、外加电压与气隙电场强度的关系,研究大气压辉光放电形成多脉冲的机理.实验结果表明,放电首先在间隙稍窄的电极左端开始;在第一个脉冲电流峰值,电极右端也开始放电;第一个电流脉冲经历了Townsend放电到辉光放电的过程;电流脉冲之间的时间内,间隙一直维持着微弱的辉光放电;随后的每个电流脉冲均是辉光放电.理论分析表明,大气压辉光放电的多个电流脉冲是表面电荷、空间电荷与外加电压共同演化的结果;除放电伊始出现Townsend放电外,同一半周期内的放电电流脉冲中不会再出现Townsend放电.
关键词:
介质阻挡放电
增强电子耦合器件
大气压辉光放电
多脉冲 相似文献
9.
G.J. Pietsch 《等离子体物理论文集》2001,41(6):620-628
The dielectric barrier discharge (DBD) is a highly transient, non‐thermal discharge form, which exists in a broad pressure range. It occurs in arrangements, where a dielectric layer covers at least one electrode. The dielectric quenches the current and distributes the discharge over the whole surface. Depending on the geometrical conditions three basic types of DBD arrangements are distinguished. In arrangements with a gas gap a filamentary or a homogeneous‐diffuse discharge mode appears. The (stable) filamentary mode consists of a multitude of microdischarges, which in some extent can be rather easily tailored for e. g. plasma‐chemical applications. In arrangements with a long electrode (or several in parallel) on a dielectric surface and a plane counter‐electrode on the reverse side of the dielectric, pure surface discharges can be observed. They are characterised by low ignition voltages. The extension of the discharge on the surface depends on the voltage amplitude. If pairs of long electrodes are within the bulk of a dielectric, discharge phenomena appear on the surface of the dielectric. As these devices can be produced with small and precise electrode gaps, high mean field strengths in the discharge region can be realised. The properties of the discharges in these arrangements as well as their dynamics are described in detail and compared with one another. The advantages of each type are highlighted. Some aspects, which may be of interest for plasma‐chemical reactions on surfaces and in the gas space are discussed. 相似文献
10.
采用稍不平行电极进行大气压He气介质阻挡多脉冲辉光放电实验,通过增强电子耦合器件相机短时曝光照片,研究大气压多脉冲辉光放电在不同时刻的放电模式.通过气隙放电电流、表面电荷计算,理论分析了表面电荷、空间电荷、外加电压与气隙电场强度的关系,研究大气压辉光放电形成多脉冲的机理.实验结果表明,放电首先在间隙稍窄的电极左端开始;在第一个脉冲电流峰值,电极右端也开始放电;第一个电流脉冲经历了Townsend放电到辉光放电的过程;电流脉冲之间的时间内,间隙一直维持着微弱的辉光放电;随后的每个电流脉冲均是辉光放电.理论分析表明,大气压辉光放电的多个电流脉冲是表面电荷、空间电荷与外加电压共同演化的结果;除放电伊始出现Townsend放电外,同一半周期内的放电电流脉冲中不会再出现Townsend放电. 相似文献
11.
大气中介质阻挡放电发光的时间特性 总被引:4,自引:0,他引:4
采用光学方法测量了大气中介质阻挡放电丝极模式的时间特性,揭示了介质阻挡放电动力学过程的时间规律。实验表明,在驱动电压的产周内的放电团簇是由多个放电脉冲构成的,放电脉冲的持续时间为30-50ns,相邻放电脉冲之间的间歇时间为几百ns。本工作的结果对介质阻挡放电的应用有重要意义。 相似文献
12.
Simulation of transition from Townsend mode to glow discharge mode in a helium dielectric barrier discharge at atmospheric pressure 下载免费PDF全文
The dielectric barrier discharge characteristics in helium at atmospheric pressure are simulated based on a one-dimensional fluid model. Under some discharge conditions, the results show that one discharge pulse per half voltage cycle usually appears when the amplitude of external voltage is low, while a glow-like discharge occurs at high voltage. For the one discharge pulse per half voltage cycle, the maximum of electron density appears near the anode at the beginning of the discharge, which corresponds to a Townsend discharge mode. The maxima of the electron density and the intensity of electric field appear in the vicinity of the cathode when the discharge current increases to some extent, which indicates the formation of a cathode-fall region. Therefore, the discharge has a transition from the Townsend mode to the glow discharge mode during one discharge pulse, which is consistent with previous experimental results. 相似文献
13.
通过数值求解一维电子、离子连续性方程和动量方程,以及电流连续性方程,计算了氦气介 质阻挡大气压辉光放电电子、离子密度和电场在放电空间的时空分布,以及放电电流密度和 绝缘介质板充电电荷密度随时间的变化. 分析讨论所加电压频率、幅值及介质板性质等对均 匀大气压辉光放电性质的影响. 当外加电压频率足够高时,大量离子被俘获在放电空间,空 间电荷场又引起足够多的电子滞留在放电空间. 这些种子电子使得在大气压下发生汤森放电 ,放电空间结构类似于低气压辉光放电,即存在明显的阴极位降区、负辉区、法拉第暗区和 等离子体正柱
关键词:
大气压辉光放电
介质阻挡
数值模拟
等离子体 相似文献
14.
通过建立一个自洽耦合的一维流体模型来描述低气压氙气介质阻挡放电(DBD),并采用有限元法对模型进行数值仿真研究,得到了不同外加电压幅值和频率下的气体间隙压降、放电电流、介质表面电荷随时间的变化关系以及电子、离子、中性粒子和空间电场的时域分布.仿真结果表明:介质表面电荷对放电的点燃与熄灭起着关键的作用;在一个放电周期内,根据气体间隙压降的变化情况,介质表面电荷可按六个阶段进行分析;随着外施电压幅值的增加,间隙击穿逐渐提前至外施电压过零点之前发生,放电更为剧烈;随着外施电压频率的提高,气体间隙压降减小,间隙容易击穿,放电也更加均匀.粒子及空间电场的时域分布表明氙气DBD为典型的辉光放电. 相似文献
15.
为了研究氩气(Ar)中介质阻挡大气压辉光放电(APGD)的放电机理, 通过建立一个一维的多粒子自洽耦合流体模型, 采用有限元方法进行数值计算, 得到了气体间隙压降、介质表面电荷密度、放电电流密度随时间的周期变化波形, 以及电子、离子、亚稳态粒子密度和空间电场强度的时空分布. 仿真计算结果表明:介质表面积聚的电荷对于放电的过程的起始及熄灭具有重要作用;当增大外施电压时, 放电击穿时刻提前, 放电电流密度和介质表面电荷密度峰值增大, 表明放电过程更加剧烈;随着阻挡介质相对介电常数的增大, 放电电流密度也随之增大. 各粒子密度及电场的时空分布表明放电过程在外施电压半个周期中只有一次放电, 且存在明显的阴极位降区、负辉区、等离子体正柱区等辉光放电的典型区域, 为大气压辉光放电(APGD). 相似文献
16.
光学方法研究介质阻挡放电中的微放电特性 总被引:7,自引:2,他引:5
首先用真空光电倍增管测量了斑图模式大气压介质阻挡放电的总光信号 ,并通过在电路中串联小电阻的方法测量了放电的电流信号。结果发现 ,两种方法所测得的信号在幅度和位置上存在严格的一致性 ,说明可以利用光学方法测量介质阻挡放电的电流信号。采用光学方法测量了介质阻挡放电中的微放电通道的时间特性。本工作所得到的结果对于介质阻挡放电的时空动力学研究具有重要意义 ,同时对气体放电研究具有一定的参考价值。 相似文献
17.
In order to study the influence of plasma on electrode, atmospheric pressure dielectric barrier discharge (DBD) air plasma is employed here to treat copper electrode surface. Plasma is generated between the parallel plate electrodes by means of high voltage produced by a high-frequency power supply with transformer. Electrode surface alterations induced by air plasma are investigated by using field emission scanning electron microscope (FE-SEM), X-ray energy dispersion spectroscopy (EDS) and contact angle measurement. The results show that DBD air plasma removes the organic contaminant on surface and causes electrode surface roughness, oxidization and nitridation. In addition, surface wettability is also improved, as concluded from contact angle measurements. 相似文献
18.
19.
圆筒状DBD放电特性模拟研究 总被引:1,自引:0,他引:1
用XOOPIC软件对同轴圆筒状反应装置DBD放电特性进行了二维模拟研究。在频率为20kHz、正弦电压幅值为5kV的大气压氩气放电中,再现了微放电通道形成和发展过程,其微放电的寿命约为4ns。获得了电子、离子、介质表面电荷密度和电场强度随空间和时间的分布,发现在高压线圈的位置附近电子、离子和介质表面电荷密度存在极值。与典型平板介质阻挡放电相比,微放电中的电子密度、场强增加2~3个数量级。 相似文献