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In order to better understand the physical mechanism of sub-microsecond pulsed glow discharge with bare metal electrodes,using a one-dimensional self-consistent fluid model,the properties of the discharge at atmospheric pressure are numerically studied.The results show that,a discharge without dielectric layers,i.e.a barrier free discharge,is extinguished only with the decrease of the applied voltage.Only one positive discharge event occurs at the slope of the pulsed voltage.A stable glow of barrier free discharge can be achieved only in short durations of the pulsed voltage.The barrier free discharge always starts with a subnormal glow discharge and then evolves into a normal glow discharge.Moreover,to control the discharge stabilization better,the effects of pulse repetition frequency,pulse duration,rising(front) and falling(slope) times on the discharge characteristics are investigated systematically.It is found that the discharge is comparatively more sensitive to the repetition frequency and the pulse duration,while little affected by the rising and falling times. 相似文献
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In this paper, a feasible scheme is reported for the detection and identification of trace alcohol congeners that have identical elemental composition using laser-induced breakdown spectroscopy (LIBS). In the scheme, an intensive pulsed laser is used to break down trace alcohol samples and the optical emission spectra of the induced plasma are collected for the detection and identifq ication of alcohol molecules. In order to prepare trace alcohol samples, pure ethanol or methanol is bubbled by argon carrier gas and then mixed into matrix gases. The key issue for the scheme is to constitute indices from the LIBS data of the alcohol samples. Two indices are found to be suitable for alcohol detection and identification. One is the emission intensity ratio (denoted as H/C) of the hydrogen line (653.3 nm) to the carbon line (247.9 nm) for identification and the other is the ratio of the carbon line (as C/Ar) or the hydrogen line (as H/Ar) to the argon lines (866.7 nm) for quantitative detection. The calibration experiment result shows that the index H/C is specific for alcohol congeners while almost being independent of alcohol concentration. In detail, the H/C keeps a specific constant of 34 and 23 respectively for ethanol and methanol. In the meanwhile, the C/Ar and H/Ar indices respond almost linearly to the alcohol concentration below 1300 ppm, and are therefore competent for concentration measurement. With the indices, trace alcohol concentration measurement achieves a limit of 140 ppm using a laser pulse energy of 300 mJ. 相似文献
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Dielectric barrier discharge plasma in air was used to modify glass surface to induce the graft of silane onto the treated surface to increase the possibility of biomolecule immobilization. The plasma treated glass had been characterized by scanning electron microscopy (SEM), Fourier transform infrared attenuated total reflection spectroscopy, X-ray photoelectron spectroscopy (XPS) and surface water contact angle measurement. The validity of grafting silane onto glass surface was approved by the analysis of water contact angle measurement, SEM and XPS. The grafted silane content was measured by visible absorption spectroscopy using acid Orange-7. It is shown that the grafting density of silane for glass samples increases significantly after plasma treatment. 相似文献
4.
Tungsten (W) accumulation in the core, depending on W generation and transport in the edge region, is a severe issue in fusion reactors. Compared to standard divertors (SDs), snowflake divertors (SFDs) can effectively suppress the heat flux, while the impact of magnetic configurations on W core accumulation remains unclear. In this study, the kinetic code DIVIMP combined with the SOLPS-ITER code is applied to investigate the effects of divertor magnetic configurations (SD versus SFD) on W accumulation during neon injection in HL-3. It is found that the W concentration in the core of the SFD is significantly higher than that of the SD with similar total W erosion flux. The reasons for this are: (1) W impurities in the core of the SFD mainly originate from the inner divertor, which has a short leg, and the source is close to the divertor entrance and upstream separatrix. Furthermore, the W ionization source (S W0) is much stronger, especially near the divertor entrance. (2) The region overlap of S W0 and $ {F}_{mathrm{W},mathrm{T}mathrm{O}mathrm{T}} $ pointing upstream promote W accumulation in the core. Moreover, the influence of W source locations at the inner target on W transport in the SFD is investigated. Tungsten impurity in the core is mainly contributed by target erosion in the common flux region (CFR) away from the strike point. This is attributed to the fact that the W source at this location enhances the ionization source above the W ion stagnation point, which sequentially increases W penetration. Therefore, the suppression of far SOL inner target erosion can effectively prevent W impurities from accumulating in the core. 相似文献
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随着总体经济水平的不断提升和群众各类新需求的出现,对行业的模式转换和整体升级带来不小的刺激作用.特别是在5G、互联网、大数据、云计算等新技术的推动下,整体上产业发展都呈现出了欣欣向荣的趋势.对于国内的电力企业而言也是如此,在战略目标的影响下,国家电网提出了基于实际情况的泛在电力物联网建设规划.这和国家电力目前所处的阶段... 相似文献
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As a spatially extended dissipated system, atmospheric-pressure dielectric barrier discharges (DBDs) could in principle possess complex nonlinear behaviors. In order to improve the stability and uniformity of atmospheric-pressure dielectric barrier discharges, studies on tem- poral behaviors and radial structure of discharges with strong nonlinear behaviors under different controlling parameters are much desirable. In this paper, a two-dimensional fluid model is devel- oped to simulate the radial discharge structure of period-doubling bifurcation, chaos, and inverse period-doubling bifurcation in an atmospheric-pressure DBD. The results show that the period-2n (n = 1, 2... ) and chaotic discharges exhibit nonuniform discharge structure. In period-2n or chaos, not only the shape of current pulses doesn't remains exactly the same from one cycle to an- other, but also the radial structures, such as discharge spatial evolution process and the strongest breakdown region, are different in each neighboring discharge event. Current-voltage characteris- tics of the discharge system are studied for further understanding of the radial structure. 相似文献
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具有高化学活性的大气压放电低温等离子体射流具有潜在的应用价值。为此,介绍了一种利用预电离办法产生Ar/O2等离子体大气压低温射流及其在表面油污清洗中的应用。采用针电极放电等离子体作为预电离源,为射流介质阻挡放电(DBD)提供种子电子,使得射流DBD的击穿与维持电压得以降低,即使在氧气与氩气体积比高达6%时,也可以产生均匀稳定的放电模式。采用光纤温度传感器检测得到放电等离子体气体温度在390~440K,而Boltzmann斜率法计算得到的电子激发温度为4640K,通过示踪元素法计算得到氧原子数密度在1017 cm-3量级。将该射流应用到玻璃表面油污清洗,最大清洗速率可达0.1mm/s。所以预电离技术可以产生具有高化学活性的均匀放电的大气压低温等离子体射流,该射流在表面油污清洗中具有较高效率。 相似文献
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A kinetic Study of Ozone and Nitric Oxides in Dielectric Barrier Discharges for O2/NOx Mixtures 总被引:1,自引:0,他引:1
A simple model is described to simulate Kinetic preocesses in dielectric barrier discharges for O2/NOx mixtures.A threshold of ozone production found experimentally is confirmed by the calculations of this modeling,and the underlying chemical reaction mechanisms are discussed.It is also found that the effects of diffusion processes in the period of the lifetime of O atoms are not important to microdischarge channels with a large radius.i.e.larger than 150μm. 相似文献
10.
王德真 《电子技术与软件工程》2019,(11):232-233
本文立足于变电运维角度,分析了变电运行中常见的故障,研究了具体的解决方法,希望以下内容的论述可以促进我国电力事业进一步发展。 相似文献