共查询到20条相似文献,搜索用时 218 毫秒
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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
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在90°磁过滤管道和MEVVA源阴极之间加30~60V的正偏压可使磁过滤管道起到阴极弧放电第二阳极的作用.在此情况下,就磁过滤管道磁场对MEVVA源阳极-阴极和磁过滤管道-阴极两个回路弧放电和磁过滤管道等离子体传输效率的影响进行了实验研究.研究结果表明随磁过滤磁场升高,磁过滤管道和阴极之间的弧放电规模降低,系统的等离子体传输效率升高,但对MEVVA源阳极和阴极之间的弧放电规模影响不大. 相似文献
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《中国核科技报告》1996,(1)
介绍SWIP-RFP装置等离子体环电压和环电流的测量方法和测量结果。对RFP环电压模型也作了初步分析,实验中采用单匝线圈测量的环电压很大程度地取决于外电路的电流,这一电压中存在一感应分量,即使考虑了测量环电压的感应分量,RFP等离子体的环电压也要大于环形磁约束系统等离子体的经典电阻环电压,这是反场箍缩等离子体螺旋量守恒的一个重要课题。对与环电压有关的电磁特性也作了一定研究。测量结果表明,SWIP-RFP装置的等离子体电流一般大于60kA,在较好的放电条件下,等离子体电流可以驱动到100kA,等离子体电流最大值时刻的单匝线圈测量的环电压约为250V。这样的结果与其它方式的估算是相对应的。测量结果还揭示了RFP装置大的等离子体电流密度和异常的环电压的存在。 相似文献
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离子源技术是等离子体研究中的一项重要内容,而低能大束流源则是离子源技术研究中的一个重要方向,因为这样的源在离子束刻蚀、离子束溅射镀膜以及荷能粒子与物质相互作用方面都有广泛的应用;本文采用空心阴极空心阳极结构,用热阴极电子发射弧放电驱动并用磁场约束产生等离子体,用曲面发射引出离子束,研制成了氩气放电溅射离子源;研究了灯丝加热电流、弧压对弧流的影响和弧流与工作气体压力对离子束引出的影响规律.离子源的引出电压在0-4.0 kV之间连续可调,最大引出束流为100 mA,束斑面积为φ6.0 cm,以Ti为溅射靶时的最大溅射沉积率为0.45 nm/s,离子源可连续工作160 h. 相似文献
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采用光谱仪测量了等离子体点火器出口射流的发射光谱,利用玻尔兹曼曲线斜率法计算了射流的电子温度,并通过电离平衡方程计算了射流气体温度,获得点火器出口射流长度、射流速度、电子温度和射流温度随弧电流及进口氩气流量的变化规律。并分析了航空等离子体电弧射流中是否可使用电子温度来代替射流气体温度。实验表明:弧电流随着进口氩气流量的增大而减小;出口射流长度和速度随弧电流的增大而增大,随进口氩气流量的增大先增大后减小;出口电子温度、电子密度和射流温度随弧电流的增大而升高,随氩气流量的增大而降低。 相似文献
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研究了阴极弧等离子体沉积中第二阳极现象改善弧放电稳定性的作用。结果表明:由于弧放电规模增大,等离子体电阻降低,第二阳极现象的存在可大幅度提高造成阴极弧放电不稳定的聚焦磁场阈值。 相似文献
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Zhefeng ZHANG 《等离子体科学和技术》2022,24(4):44002
As the main source of the vacuum arc plasma, cathode spots (CSs) play an important role on the
behaviors of the vacuum arc. Their characteristics are affected by many factors, especially by the
magnetic field. In this paper, the characteristics of the plasma jet from a single CS in vacuum arc
under external axial magnetic field (AMF) are studied. A multi-species magneto-hydro-dynamic
(MHD) model is established to describe the vacuum arc. The anode temperature is calculated by
the anode activity model based on the energy flux obtained from the MHD model. The
simulation results indicate that the external AMF has a significant effect on the characteristic of
the plasma jet. When the external AMF is high enough, a bright spot appears on the anode
surface. This is because with a higher AMF, the contraction of the diffused arc becomes more
obvious, leading to a higher energy flux to the anode and thus a higher anode temperature. Then
more secondary plasma can be generated near the anode, and the brightness of the ‘anode spot’
increases. During this process, the arc appearance gradually changes from a cone to a dumbbell
shape. In this condition, the arc is in the diffuse mode. The appearance of the plasma jet
calculated in the model is consistent with the experimental results. 相似文献
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Yawen CAO Bin LI Xianwei HAN Chang TAN Zhihao ZHANG Xizhe ZHANG Jianguo WEI 《等离子体科学和技术》2021,23(6):64006-58
Arc plasma can be applied in hazardous solid waste disposal for higher temperature than common heating methods, but some practical issues exist in practical engineering application. In this study, an air arc plasma torch with double chambers and magnetic controlling is designed to realize wide variable power and long electrode life. The detailed characteristics and laws of the air arc are studied. The condition parameters of arc current(I), air flow rate(G) and the structure parameters of inlet area ratios and electrode diameters influence both the arc voltage and arc root positions. The arc rotating driven by magnetic field effectively lengthens the electrode life. The gasification process and product of organic wastes by air plasma are influenced largely by the waste compositions and the air flow rate. A furnace structure with more even atmosphere and longer residence time should be considered for better gasification. Oxygen-deficient environment is important to suppress NOxformation during the application of air plasma. Inorganic solid wastes can be melt by the air plasma and cooled down to form compact vitreous structures in which heavy metals can be locked and the leaching rates significantly decrease down. 相似文献
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In this work, a magnetic fluid dynamics (MHD) model is used to simulate the electromagnetic field, heat transfer and fluid flow in a DC non-transferred arc plasma torch under laminar and turbulent conditions. The electric current density, temperature and velocity distributions in the torch are obtained through the coupled iterative calculation about the electromagnetic equations described in a magnetic vector potential format and the modified fluid dynamics equations. The fluid-solid coupled calculation method is applied to guarantee the continuity of the electric current and heat transfer at the interface between the electrodes and fluid. The predicted location of the anodic arc root attachment and the arc voltage of the torch are consistent with corresponding experimental results. Through a specific analysis of the influence of mass flow rates and electric current on the torch outlet parameters, the total thermal efficiency, thermal loss of each part, and the laws of the variation of outlet parameters with the variation of mass flow rates and electric current was obtained. It is found that operation under a laminar condition with a limited area of the anode could increase the total thermal efficiency of the torch. 相似文献
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In this report,two new contact structures of a vacuum interrupter with a sinusoidal curved surface are proposed to improve the capability by increasing the surface area.The experimental investigation of vacuum arc at intermediate frequency(360-800 Hz)was conducted and the results were compared with a butt contact with the same contact diameter(41 mm)and the same material.By analyzing the arc behavior,arc voltage characteristics,arc energy,current interrupting capacity,ablation of the anode contact and condensation of the arc products at a 3 mm gap,the differences in their vacuum arc characteristics were determined.The correlations of their arc energy with the amplitude and the frequency of the current were also achieved.Analysis suggests that the ruled curved contact has strong application potentiality because of its low arc energy,low arc voltage noise and arc voltage peak,light ablation on the surface of the anode contact and high interrupting capacity. 相似文献
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This paper focuses on the simulation of the low-voltage arc with an opening contact. A controllable experiment setup with a rotating contact is designed to investigate the arc behaviour. Supported by the experiment, the phenomena of arc elongation and commutation in the case of rotating contact are simulated with the dynamic grid technique introduced. Under the given condition of the external magnetic field and the contact rotating velocity, the stagnation and rapid jump of two arc roots are observed by the calculated and experimental arc root displacement. The voltage of arc column can be divided into four phases and its sharp rising progress comes from the increase of the displacement difference between two arc roots in x direction. 相似文献
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The effects of feed gas flow rate and operating current on the electrical characteristics and dynamic behavior of a rotating gliding arc (RGA) plasma codriven by a magnetic field and tangential flow were investigated.The operating current has been shown to significantly affect the time-resolved voltage waveforms of the discharge,particularly at flow rate =21 min-1.When the current was lower than 140 mA,sinusoidal waveforms with regular variation periods of 13.5-17.0 ms can be observed (flow rate =21 min-1).The restrike mode characterized by serial sudden drops of voltage appeared under all studied conditions.Increasing the flow rate from 8 to 121 min-1 (at the same current) led to a shift of arc rotation mode which would then result in a significant drop of discharge voltage (around 120-200 V).For a given flow rate,the reduction of current resulted in a nearly linear increase of voltage. 相似文献
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Zelong ZHANG 《等离子体科学和技术》2022,24(5):55402
A 2D self-consistent numerical model of the whole argon-arc discharge region that includes electrodes is developed in this work to facilitate analysis of the physical processes occurring in atmospheric arc plasma. The 2D arc column model contains the ionization and thermal non-equilibrium, which is coupled with a 1D electrode sheath model. The influence of plasma-species diffusion near the electrode region is investigated based on Maxwell–Stefan equations and the generalized Ohm's law. The numerical results of argon free-burning arcs at atmospheric pressure are then investigated. The simulation shows that the plasma is obviously in the state of thermal and ionization equilibrium in the arc core region, while it deviates from thermal and ionization equilibrium in the arc fringe region. The actual electron density decreases rapidly in the near-anode and near-cathode regions due to non-equilibrium ionization, resulting in a large electron number gradient in these regions. The results indicate that electron diffusion has an important role in the near-cathode and near-anode regions. When the anode arc root gradually contracts, it is easy to obtain a positive voltage drop of the anode sheath (I = 50 A), while it remains difficult to acquire a positive anode sheath voltage drop (I = 150 A). The current–voltage characteristics predicted by our model are found to be identical to the experimental values. 相似文献
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Results observed experimentally are presented, about the DC arc plasma jets and their arc-root behaviour generated at reduced gas pressure without or with an applied magnetic field. Pure argon, argon-hydrogen or argon-nitrogen mixture was used as the plasma-forming gas. A specially designed copper mirror was used for a better observation of the arc-root behaviour on the anode surface of the DC non-transferred arc plasma torch. It was found that in the cases without an applied magnetic field, the laminar plasma jets were stable and approximately axisymmetrical. The arc-root attachment on the anode surface was completely diffusive when argon was used as the plasma-forming gas, while the arc-root attachment often became constrictive when hydrogen or nitrogen was added into the argon. As an external magnetic field was applied, the arc root tended to rotate along the anode surface of the non-transferred arc plasma torch. 相似文献