Analysis of Magnetic Field of the DNB Ion Source

A distribution of the magnetic field produced by permanent magnets in the DNB ion source is calculated and analyzed in order to understand the plasma confinement in a cusped magnetic field and optimize plasma discharge. A uniform plasma is obtained in the experiment.     

单脉冲磁场精确设定装置的研制

本文介绍了一种用于磁镜装置研究中脉冲磁场精确设定的装置，其重复精度误差小于１／１０００。     

Effect of Mirror Magnetic Field on Abnormal Glow Discharge of Four-Anode Device

Abstract In the four-anode device, the mirror magnetic field affects the characteristics of charged particles motion, so that the current-voltage relations of glow discharge are changed. Firstly, the discharge device is introduced, and the distribution of mirror magnetic field generated by the loops surrounding the discharge chamber is presented. Both the discharge current-voltage characteristics and the radial distributions of electron density are measured, respectively, with/without the magnetic field. When the discharge occurs in a 99.99% helium with a pressure ranging from 100 Pa to 800 Pa without magnetic field, the voltage, sustaining a certain abnormal glow discharge current, decreases with the increase in gas pressure. With a mirror magnetic field of certain intensity, the discharge voltage increases with the current in a rate slower than that without the magnetic field. Moreover, when the magnetic field intensity increases, the discharge voltage first decreases then increases. Simultaneously, the mirror magnetic field affects the moving characteristics of charged particles, and causes a more inhomogeneous electron density.     

High-Beta Steady-State FRC Plasma Sustained by Rotating Magnetic Field with Spatial High-Harmonic Components

Field-reversed configurations (FRCs) driven by rotating magnetic fields (RMFs) with spatial high-harmonic components have been studied in the metal flux conserver of the FRC injection experiment (FIX). The high-harmonic RMF method has some unique features; (1) field lines of the RMF do not penetrate or cross the vessel wall, (2) selective penetration/exclusion of the fundamental/high-harmonic RMF component will result in a generation of effective magnetic pressure near the separatrix, which helps to keep the separatrix away from the vessel wall, (3) strong azimuthal non-uniformity of the RMF will cause the n = 4 deformation of the core FRC plasma, which will eliminate the destructive modes caused by the rotation of the plasma column. The RMF method with high harmonics will provide quasi-steady current drive of high-beta FRC plasmas without destructive n = 2 rotational mode and will be helpful in reducing the particle loss and thermal load when applied to the fusion core plasma.     

Upgrading of the Magnetic Confinement Plasma Device KT-5E

In this article we present ideas of providing appropriate poloidal magnetic field for helimaks to help to generate toroidal magnetic plasma torus. Placing a conductive ring in the center of the cross-section to induce a suitable current, we change the helical magnetic field lines in the helimak discharge into magnetic surface. In this kind of discharge, the plasma density is greatly increased, and the corresponding density fluctuation is significantly decreased, showing a better confinement by magnetic shear. It allows more flexible and efficient experimental investigations on the toroidal magnetic confinement plasmas to be carried on in this kind of device.     

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.     

Calculation and Analysis of Magnetic Field Pattern for TEXT—U Equipment

In this paper,the toroidal field B of a tokamak produced by separate coils has been calculated from the basic electrodynamic theory.As an example,the toroidal magnetic field B(R) in TEXT-U tokamak is plotted.and the curve is fitted well to the analysis formula B(R)=B0R0/R with a precision of several percents.     

Simulation Research of Magnetic Constriction Effect and Controlling by Axial Magnetic Field of Vacuum Arc

Based on magnetohydrodynamic (MHD) model of vacuum arc, the computer simulation of vacuum arc was carried out in this paper. In the MHD model, mass conservation equation, momentum conservation equations, energy conservation equations, generalized ohm‘s law and Maxwell equation were considered. MHD equations were calculated by numerical method, and the distribution of vacuum arc plasma parameters and current density were obtained. Simulation results showed that the magnetic constriction effect of vacuum arc is primarily caused by the Hall effect. In addition, the inhibition of axial magnetic field (AMF) on constriction of vacuum arc was calculated and analyzed.     

Dynamics of Dust in a Plasma Sheath with Magnetic Field

Dynamics of dust in a plasma sheath with a magnetic field was investigated using a single particle model. The result shows that the radius, initial position, initial velocity of the dust particles and the magnetic field do effect their movement and equilibrium position in the plasma sheath. Generally, the dust particles with the same size, whatever original velocity and position they have, will locate at the same position in the end under the net actions of electrostatic, gravitational, neutral collisional, and Lorentz forces. But the dust particles will not locate in the plasma sheath if their radius is beyond a certain value.     

The Drift of Dust Grains Induced by Transient Magnetic Field

Our experiment shows that the dust grains ,suspended on the edge of the sheath of a radio-frequency discharge,undergo a contraction when switching a vertical magnetic field on ,and an expansion when switching the magnetic field off .We call this kind of magnetic field“transient magnetic field”.A primary analysis is proposed for the phenomenon.     

Detailed Magnetic Field Measurement on a Hybrid Undulator for the JAERI FEL

A planar hybrid undulator was constructed for the JAERI PEL. In order to evaluate the performance of the undulator, magnetic field of the undulator was mapped by a detailed field measurement system. The field map obtained experimentally was compared with the map calculated by computer. The undulator field was found to be sinusoidal in the longitudinal direction and almost flat In the transverse direction. The performance of the undulator was found out to be sufficient to lase the JAERI FEL, because the irregularity of the field pattern of the undulator is sufficiently small.     

Research on Nanosecond Pulse Corona Discharge with Cross Magnetic Field Applied

An application of magnetic field to the nanosecond pulse corona discharge is investigated. A cylinder reactor with different corona electrodes is set up for experimental study. A magnetic field with its direction perpendicular to the corona discharge is applied. Different discharge images are taken under single nanosecond pulse with a high sensitive UV-visible light imagine recorder. Experimental results show that with a cross magnetic field the nanosecond corona discharge both generates paths and develops homogeneously in space more than that without the magnetic field. The results may lead to a possibility to apply a cross magnetic field on nanosecond pulse corona discharge for getting higher desulfurization efficiency.     

Redistribution of Gaseous Phase of Liquid Metal Two-Phase Flow in a Strong Magnetic Field

In the previous paper, the authors pointed out the motion of bubble or gaseous phase in the direction to the both side walls due to the pinch effect caused by the induced magnetic field in the liquid metal two-phase flow under the strong magnetic field. In the present paper, to clarify the existence of the pinch effect experimentally, an experimental study was performed.

Firstly the distributions of the void fraction in the cross section perpendicular to the flow were measured at three locations in the flow direction for the various strength of the applied magnetic field. Secondly a magnetic field was superposed on the induced magnetic field by the outer coil to disturb the pinch effect by the cancel of the induced magnetic field with the superposed one, resulting in the evident redistribution of the void-fraction profile obtained above.

From these experiments it is concluded that the pinch effect will play an important role to redistribute the bubble or gaseous phase in the liquid metal two-phase flow under the strong magnetic field and that the effect is more promoted with increasing magnetic interaction number defined as a ratio of the electromagnetic force to the inertia of the fluid.     

加速器中磁场矢函的3种展开形式

用正则变换、复平面展开、泰勒展开3种不同的方法对磁场矢函的表达式进行推导，得出3种磁场矢函表达式。对3种磁场矢函表达式进行了比较分析。在一定的条件下，3种表达式可以写成统一的表达式。在实际的研究中，可根据具体情况选择适当的表达式。     

Influence of Magnetic Field on Boiling of Stagnant Potassium

Abstract

The influence of a magnetic field on the boiling of stagnant potassium was experimentally studied in the range of field intensity from 0 to 0.7 Tesla under low pressure cover gas. The results indicated that incipient boiling superheat and the location of boiling inception were not influenced by the magnetic field. On the other hand, the magnetic field very appreciably impeded the motion of the liquid column supported above the vapor bubble after boiling was initiated. Another effect of the magnetic field proved to be inhibition of vapor condensation in the void space during the period of descend of the liquid column. As a result the vapor in the void space remained uncondensed, to serve as permanent cushion for the liquid column, which maintained an oscillatory motion, to which corresponding oscillations were registered in the pressure and temperature of the vapor bubble, which changed along the vapor saturation line.     

Incipient Boiling of Sodium in Presence of Magnetic Field

A three-dimensional nuclear and thermo-hydrodynamic kinetics calculation code IBIS has been developed, envisaging the treatment of asymmetrical reactivity changes in a large fast breeder reactor. An example of calculation with this code is described, which reveals a difference of void propagation behavior, following a local disturbance, between homogeneous and heterogeneous cores, ascribable to the presence, in the latter case, of inner blanket layers, which act as barrier against void propagation. Of the two parameters of power-to-flow ratio and space-time variation in thermal power, the latter is the more influential on void propagation, and this makes it essential to perform three-dimensional space-dependent kinetic analysis for adequately simulating local perturbations in a heterogeneous core.     

过滤管道磁场在改进真空弧沉积系统中的作用

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.     

Efficiency of Removing Sulfur Dioxide in the Air by Non-Thermal Plasma Along with the Application of the Magnetic Field

1 IntroductionSO2 is one of the main hazards to human health, andit is the main component of the acidic oxides in the at-mosphere. The menace of the acidic pollution by SO2can be curtailed if it is removed from the air. In recenttime, researchers across the world have been concernedabout efficient removal of SO2.Several techniques have been applied to decompos-ing SO2 in the air in recent years. At present, themain technologies for removing sulfur dioxide include:the gas-phase reaction [1]…     

Absolute Measurements of the Magnetic Field Generated by Different Coils in the Center of EGYPTOR Tokamak

The present work is devoted to measure the absolute magnetic field produced by different coils in the EGYPTOR tokamak using a calibrated pickup coil. Scaling these measurements in different equations connected with the discharge currents from each supply system are performed. The pickup coil used in the present study is well calibrated with Helmholz coils at the IPP in Prague, Czech Republic. A 0.2% deviation has been found between an evaluation done in the present study and the calibration using Helmholz coils. Experimental measurements of the toroidal magnetic field are in good agreement with calculations to within 2%. Very low values of stray magnetic field components arising from TF and OH coils are recorded which proves that the compensation coils for these components are sufficient.     

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.