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1.
There are many cathode electron emission mechanisms which have been discussed [1]. But in arc discharge ) the thermionic and the field emission playan important role. The electron emission has influence on the properties of cathode fall region, whichcan be divided into two subzonesf space charge zoneand ionization zone [21. In this paper, the spacecharge zone is called cathode sheath (CS). The cathode sheath, being nearest to the cathode surface, isaffected by the electron emission first. Th… 相似文献
2.
Magnetically dispersed arc plasma [1] exhibits typically dispersed uniform arc column as well as diffusive cathode root [1,2] and diffusive anode root.In this paper magnetically dispersed arc plasma coupled with solid cathode is numerically simulated by the simplified cathode sheath model of LOWKE [3].The numerical simulation results in argon show that the maximum value of arc root current density on the cathode surface is 3.5×10 7 A/m 2,and the maximum value of energy flux on the cathode surface is 3×10 7 J/m 2,both values are less than the average values of a contracted arc,respectively. 相似文献
3.
CTB型电流互感器二次过电压保护器 总被引:1,自引:0,他引:1
引言随着电力工业大容量机组和高压电网的迅速发展,为了对运行中的发电机、交流励磁机、输电线路进行必要的电气测量、自动控制和各种继电保护的配置,电力设计部门专门为这些元件出口配置了各种规格的电流互感器(简称CT)。在运行中,电流互感器一旦二次开路,将会呈现出畸异的高电势,造成人身事故和设备故障,导致重大经济损失。目前。日本已研 相似文献
4.
The gliding arc is an important approach to production of non-thermal plasma at atmospheric pressure, it can offer high-energy efficiency and high-electivity for chemical reactions. In this paper, the gliding arc driven by the transverse magnetic field is described and its velocity is measured by using a photo-multiplier. The mean velocity of the gliding arc increases with increasing magnetic induced-intensity, and its value varies from 7.8 m/s to 32 m/s. 相似文献
5.
Generation of reactive species in atmospheric pressure dielectric barrier discharge with liquid water 总被引:1,自引:0,他引:1
Atmospheric pressure helium/water dielectric barrier discharge(DBD) plasma is used to investigate the generation of reactive species in a gas–liquid interface and in a liquid. The emission intensity of the reactive species is measured by optical emission spectroscopy(OES)with different discharge powers at the gas–liquid interface. Spectrophotometry is used to analyze the reactive species induced by the plasma in the liquid. The concentration of OH radicals reaches 2.2 μm after 3 min of discharge treatment. In addition, the concentration of primary longlived reactive species such as H_2O_2, NO_3~- and O_3 are measured based on plasma treatment time.After 5 min of discharge treatment, the concentration of H_2O_2, NO_3~-, and O_3 increased from 0 mg?·?L~(-1) to 96 mg?·?L~(-1), 19.5 mg?·?L~(-1), and 3.5 mg?·?L~(-1), respectively. The water treated by plasma still contained a considerable concentration of reactive species after 6 h of storage. The results will contribute to optimizing the DBD plasma system for biological decontamination. 相似文献
6.
传统炭黑生产过程热能效率低,存在大量NOx和CO2排放,炭黑收率低。等离子体法生产炭黑能大幅提高能量利用效率,理想状况下可以完全收获原料中的碳,并消除由于燃烧产生的CO2和NOx排放。基于Aspen Plus软件模拟了炉法炭黑和等离子体法炭黑工艺过程。计算分析了等离子体法炭黑工艺相对于炉法炭黑工艺的节能效果:对于炉法炭黑分别计算了N110、N220、N330、N440和N550五种炭黑品种的过程(火用)流,等离子体法炭黑计算了甲烷和焦油两种原料的过程(火用)流;对比分析了两种工艺过程炭黑收率、进出料(火用)流、产品(火用)效率以及工艺过程(火用)效率。结果表明:以焦油为原料的炉法炭黑收率在47.6%~66.6%之间,与实际值吻合,明显低于等离子体法94%的理想炭黑收率;以焦油为原料的理论计算表明,等离子体法炭黑产品(火用)效率和工艺过程(火用)效率显著高于炉法炭黑;以焦油为原料的等离子体法炭黑产品(火用)效率高于以甲烷为原料的产品(火用)效率。 相似文献
7.
A 3-phase a.c. arc plasma reactor with large volume plasma has been developed for the synthesis of new carbon nano-structures. One of the main characteristics of the plasma system is related to the absence of a fixed neutral point. This gives rise to a rich and complex phenomenology related to instabilities and arc motion since the arcs are "burning" freely in the gas flow between the three electrodes.
This paper is dedicated to the analysis of the behavior of such a system under typical conditions using argon and nitrogen as plasma gases. A classification of are configuration, arc commutating, arc interaction, arc motion and arc instabilities are discussed based on ultra high-speed cine camera analysis. A simple model describing the time evolution of the system is also presented and compared with the experimental measurements. The results show that an adequate control could allow the improvement of the overall system. 相似文献
8.
The effect of an axial magnetic field (AMF) on an old xenon short-arc lamp is experimentally investigated in this work. As the AMF increases up to 18 roT, the visible radiation power and electric power ascend more than 80% and 70% respectively, and the radiation efficiency is improved by 23% for the best increment at 12 mT AMF. The measurement of radiation intensity shows that the increment of radiation intensity comes mostly from the plasma area close to the cathode tip, and partially from the other area of the arc column. Successive images of the arc indicate that the arc column not only rotates about its axis, but revolves around the axis of electrodes with the AMF. The arc column structure is constricted, distorted and elongated as the AMF increases. It is suggested that the improvements of the radiation intensity and radiation efficiency are attributed to the constriction of the arc column, which is mainly induced by the enhanced cathode jet. 相似文献
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10.
介绍了一种用于煤粉点火等离子体发生器的实验装置,由一对并联的条形平行布置的阳极和同平面布置的圆柱形阴极构成,它们设置在煤粉输运通道中。采用高速CCD摄像和电弧电气参数测量等方法,研究了电弧形状、弧根的运动规律等。试验结果表明:(1)阳极弧根沿电极轴向无规则快速跳动及在两条电极间交替跳跃,这种弧根的快速跳跃有利于降低阳极损耗;(2)电弧在两条阳极之间的弧室内呈现不规则快速变化扭曲形状,使电弧弥漫于整个弧室,煤粉通过电弧放电通道高温区时与电弧混合而点火,使等离子体点火效率有了显著提高。 相似文献