Exploration to generate atmospheric pressure glow discharge plasma in air

Atmospheric pressure glow discharge (APGD) plasma in air has high application value.In this paper,the methods of generating APGD plasma in air are discussed,and the characteristics of dielectric barrier discharge (DBD) in non-uniform electric field are studied.It makes sure that APGD in air is formed by DBD in alternating current electric field with using the absorbing electron capacity of electret materials to provide initial electrons and to end the discharge progress.Through designing electric field to form two-dimensional space varying electric field and three-dimensional space varying electric field,the development of electron avalanches in airgap is suppressed effectively and a large space of APGD plasma in air is generated.Further,through combining electrode structures,a large area of APGD plasma in air is generated.On the other hand,by using the method of increasing the density of initial electrons,millimeter-gap glow discharge in atmospheric pressure air is formed,and a maximum gap distance between electrodes is 8 ram.By using the APGD plasma surface treatment device composed of contact electrodes,the surface modification of high polymer materials such as aramid fiber and polyester are studied and good effect of modifications is obtained.The present paper provides references for the researchers of industrial applications of plasma.     

金属腐蚀探测技术及其应用

地下金属管及建筑物中的钢筋发生腐蚀不仅导致重大经济损失,而且还可引发环境污染,并孕育安全事故隐患。为此,必须要对金属物体发生腐蚀的区段实施防腐工程。为做到准确施工,必须在施工前查明腐蚀区段的分布,并确定其位置。物探中的许多方法,如电化学方法、电阻率法和电磁法等均可在不破坏介质的情况下,快速探测出金属物体的腐蚀区段,为防腐工程提供腐蚀定位资料。此外。还介绍了由上述物探方法演变而成的金属腐蚀探测技术及其在国外的应用实例。     

Deactivating Metal Particle by Optimizing Insulation Configuration in Spark Gap Switch

As a new method to protect the spark gap from metal particle contamination, the effect of the metal inserted insulator on the controlling behavior of metal particles was investigated in a quasi-uniform electric field. Considering that the inserted metal electrodes can decrease the electric field around the insulator and divert the electrostatic force away from the insulator, the method can be used to prevent the particles from moving toward the insulator so as to reduce the possibility of a breakdown. The inserted metal electrodes can reverse the direction of the particles＇ horizontal motion. A study on the insulator shape indicates that the inserted metal electrodes can repulse the particle and improve the particle lifting voltage significantly near the vertical surface of the insulator or ribbed insulator. For the insulator with a tilting surface the inserted metal electrodes have little influence on the particle motion. In addition, the size of the inserted electrodes shows a significant effect on the control of particle motion.     

Generation characteristics of a metal ion plasma jet in vacuum discharge

To improve the performance of a metal ion plasma jet in vacuum discharge,an anode-insulated cone-cylinder electrode with insulating sleeve is proposed in this paper.Discharge characteristics and generation characteristics of plasma of the electrode are investigated,effects of diameter of insulating sleeve,variety of cathode material and length of the insulating sleeve on characteristics of metal ion plasma jet are discussed.Results indicate that a directional and steady plasma jet is formed by using the novel electrode with insulating sleeve under high vacuum conditions.Moreover,the properties of metal ion plasma jet are improved by using the aluminum cathode and thin and long insulating sleeve.The study provides strong support for research of vacuum metal ion plasma thruster and ion implantation technology.     

Arc Behaviours in Vacuum Interrupters with Axial Magnetic Field Electrodes

To improve the limiting current interruption capability and minimizing vacuum interrupter with axial magnetic field （AMF） electrodes, it is significant to investigate the vacuum arc behaviours between the contacts. AMF distributions of the slot type electrodes were studied by both numerical analysis and experiments. Furthermore, the behaviours of vacuum arcs for different parameters of the slot type AMF electrodes were investigated by using high-speed CCD camera. The influences of gap distance, contact diameter and phase shift time between AMF and arc current on the vacuum arc were investigated. The results provide a reference for research and development of vacuum interrupters with slot type or other types of AMF electrode.     

Characteristics of modified CT injector for JFT-2M

The HIT-CTI mark II compact toroid (CT) injector employed for the JFT-2M tokamak facility at the Japan Atomic Energy Research Institute (JAERI) has been upgraded to improve injection performance. The nozzle of the mark III injector now has a linear tube in place of the original focus cone to avoid rapid focus and deceleration, and the tapered outer electrode has been replaced with more gentle taper in the compression section in order to facilitate gradual compression. The dependence of CT velocity and electron density on poloidal bias flux and trigger time of CT acceleration have been investigated in the operable range of 70–230 km/s average CT velocity and electron density of 0.1–1.0 × 10²² m⁻³ at an accelerator bank voltage of 25 kV. The operation window is broader than that of the mark II injector. Emission of a CT plasmoid from the injector, and transport to the flux conserver as a high-density spheromak magnetic structure have also been confirmed.     

Effect of polarization force on the Jeans instability in collisional dusty plasmas

The Jeans instability in collisional dusty plasmas has been analytically investigated by considering the polarization force effect.Instabilities due to dust-neutral and ion-neutral drags can occur in electrostatic waves of collisional dusty plasmas with self-gravitating particles.In this study,the effect of gravitational force on heavy dust particles is considered in tandem with both the polarization and electrostatic forces.The theoretical framework has been developed and the dispersion relation and instability growth rate have been derived,assuming the plane wave approximation.The derived instability growth rate shows that,in collisional dusty plasmas,the Jeans instability strongly depends on the magnitude of the polarization force.     

蒸汽湿度电容传感器内部电场与流场耦合特性数值研究

基于电介质极化和蒸汽流动的基本理论,利用FLUENT软件的二次开发功能,对蒸汽湿度电容传感器内部蒸汽流场和电场进行了理论分析和耦合特性的数值模拟。湍流模型采用标准k-ε模型,近壁区采用壁面函数法,电场和流场方程均使用SIMPLE算法。研究结果表明：当蒸汽为单相饱和蒸汽时,电容传感器内部电势由正极板向负极板逐渐减小,且变化较均匀,电荷主要分布在极板附近,内部区域无极化电荷;电场对流场的影响主要体现在极板附近蒸汽的径向流速上,最外层极板附近电场对流场的影响最大;流场对电场的影响主要体现在电极板的边缘效应上,有流场时极板附近的电场强度较无流场时低;数值模拟结果与实验结果的相符程度较好。     

Numerical Simulation of Tripolar Vortex in Dusty Plasma with Sheared Flow and Sheared Magnetic Field

This article presents a study we have made of one class of coherent structures of the tripolar vortex. Considering the sheared flow and sheared magnetic field which are common in the thermonuclear plasma and space plasma, we have simulated the dynamics of the tripolar vortex. The results show that the tripolar vortex is largely stable in most cases, but a strongly sheared magnetic field will make the structure less stable, and lead it to decays into single vortices with the large space scale. These results are consistent with findings from former research about the dipolar vortex.     

Distribution of Cathode Spots in Vacuum Arc Under Nonuniform Axial Magnetic Fields

Recent results on the distribution of vacuum arc cathode spots （CSs） in nonuniform axial magnetic field （AMF） are presented. Based on previous studies, we deem that two contrary influences of AMF, inward effect and outward effect, are attributed to CSs distribution. With this notion, we have analyzed the controlling effectiveness of nonuniform AMF on CSs distribution. Experiments were conducted in a detachable vacuum chamber with iron-style AMF electrodes. Images of vacuum arc column and the distribution of CSs were photographed with a high-speed charge coupled device （CCD） camera. Experimental results agreed well with the theoretical analysis.     

Initial Vacuum Magnetic Field Mapping in the Compact Toroidal Hybrid

The Compact Toroidal Hybrid (CTH) is a low aspect ratio (R/a_plasma ≥ 3.5, R₀ = 0.75 m, a_vessel = 0.29 m, B ≤ 0.6 T) torsatron with a highly flexible vacuum magnetic field configuration designed for current-driven instability studies. Vacuum magnetic field mapping of the completed configuration is performed using a movable electron gun and phosphor-coated screen. These experiments compare the actual magnetic configuration with the design, verify the range of accessible magnetic configurations, and identify vacuum field errors. The main helical field is produced by a continuously-wound helical coil, and the vacuum rotational transform is varied with a set of toroidal field coils. Four independent poloidal field coil sets provide equilibrium control and shaping, and are also used for ohmic current drive.     

Plasmas: Diversity, Pervasiveness and Potential

When considered inclusively, plasma science and technology encompass immense diversity, pervasiveness and potential: diversity through numerous topical areas (see list of nearly 200 in Table II); pervasiveness with examples covering the full range of energy, time and spatial scale; and potential through innumerable current and future applications.     

In_(0.95)Ag_(0.045)Ga_(0.005)合金中的电四极相互作用

本文采用时间微分扰动角关联方法,测量了80—422K温度范围内~(111)Cd在In_(0.95)Ag_(0.043)Ga_(0.005)合金中的四极相互作用随温度的变化,进而导出晶格电场梯度的温度变化。在In_(0.95)Ag_(0.043)Ga_(0.005)合金中,晶格电场梯度的温度变化遵从T~(3/2)定律:V_(zz)(T)=V_(zz)(0)(1—BT~(3/2)),斜率B=7.48(47)·10~(-5)K~(-3/2)。在80、298和422K的电场梯度分布宽分别为0.1147(259)、0.0924(340)和1.344(175)。表明在液氮温度和室温时,合金的晶格结构特性较好,温度升高,晶格结构特性变坏。     

High Field Tokamaks for Burning Plasma Experiments

A direct consequence of the ELMy H-mode regime of tokamaks is that, for a constant value of the energy gain Q, both the plasma linear dimension and the normalized plasma density and beta are decreasing functions of the toroidal magnetic field. In this paper, starting from the conditions foreseen for the latest versions of ITER, we derive the plasma parameters of three tokamak plasmas with a toroidal magnetic field of 8, 10, and 13 T.     

The Impact of Electrode Configuration on Characteristics of Vacuum Discharge Plasma

Generation characteristics of vacuum discharge plasma are very important for the applied research of metal plasma. The vacuum discharge electrode configuration and the cathode material affect the generation characteristics of the metal plasma which consists of metal ions coming from cathode and generated by vacuum discharge. In this research, the generation characteristics of the metal plasma generated by vacuum discharge are discussed for four patterns of electrode configurations, i.e. cone-mesh electrode setup, cone-cross line electrode setup, cone-line electrode setup and cone-ring electrode setup. Characteristics of the metal plasma, such as elec- tron density, electron temperature, space potential, ion energy, are measured by the probe method for discussing the impacts of different electrode configurations on the density of generated metal plasma. Moreover, the diffusion velocities of the metal plasma are measured for cathode materials of Pb, Al, and Cu, respectively. The experimental results indicate that the plasma generated by the discharge of cone-ring electrode configuration possesses the maximum density and the metal plasma generated by the Al cathode possesses the fastest diffusion velocity and the highest kinetic energy.