磁通门磁变仪状态函数的测定与记录的校正计算

对磁通门磁变仪状态函数的测定方法进行了研究，提出了磁通门磁变仪标度值——状态函数的测定和磁通门磁变仪记录的校正计算方法。     

三分量磁通门磁变仪和经典磁变仪记录的比较

对磁通门磁变仪和经典光记录磁变仪记录进行比较分析。认为可以用磁通门磁变仪记录和处理日常数据。用经典磁变仪来判断和改正磁通门磁变仪的记录错误。     

磁通门磁变仪状态函数对电磁转换函数测定值的影响

分析了磁通门磁变仪定向状态函数对电磁转换函数测定位的影响，指出在利用转换函数分析预报地震时，定向状态函数的影响不容忽视。     

环境对磁通门磁变仪定向影响的分析

磁通门磁变仪实际工作在弱铁磁环境。本文分析了弱铁磁环境等对磁通门磁定仪定向的影响，得出了弱铁磁影响等环境中磁通门磁变仪准确定向的方法。     

磁通门磁变仪定向状态函数的稳定性分析

在地磁观测中 ,磁变仪的稳定性是基本要求。磁通门磁变仪的稳定性依赖于电子反馈、补偿线路的稳定性和磁通门磁变仪定向状态函数的稳定性。本文对后者进行讨论。1　磁通门磁变仪的定向要求磁通门磁变仪的定向就是使传感器线圈轴方向与被测磁场方向一致。设磁通门 3个探头线圈分别与定向方向 X、Y、Z间有微小差角 ,省略电子放大部分 ,忽略温度影响 ,有(周锦屏等 ,1 999)TX =X0 + SXn X=X + tanε* Y + tanβX* Z ( 1 )TY=Y0 + SYn Y=Y + tanδ* X + tanβY* Z ( 2 )TZ=Z0 + SZn Z-Z + tanθX* X + tanθY* Y ( 3 )其中 X0 ,Y0…     

数字三分量磁通门磁变仪定向的研究

本文对磁通门磁变仪定向标准、定向稳定性、影响定向的因素进行了分析，将定向标准分为定向操作标准和定向期望标准，讨论了实际记录精度等问题。     

H磁变仪的定向讨论

Ｈ磁变仪的定向讨论叶富华（中国四川６１１７３０成都地震台）通常认为，Ｈ磁变仪（以下简称Ｈ仪）的精确定向应是在没有Ｚ磁系等铁磁物质影响的所谓无磁环境中，用“扭头带动镜面法”（简称镜面法）定向，然后再做Ｚ仪的影响改正。在实际工作中，Ｈ仪需要重新定向的情况...     

磁偏角变化对垂直分量磁变仪记录影响的实验

实验证实了磁偏角变化对垂直分量磁变仪记录有影响。对于磁南北向布局中的垂直分量磁变仪，Ｚ磁针偏离定向位置θ０＝０越远，磁偏角变化对垂直分量磁变仪记录的影响越大。认为应重视垂直分量磁变仪遥定向工作并有必要提高垂直分量磁变仪磁针稳定性。     

磁偏角磁变仪的定向

分析了影响磁偏角磁变仪定向质量的原因，指出应重视阻尼器影响，提出磁偏角磁变仪以在实际工作环境中定向最佳，用扭头带动镜面法定向实用性强，无须做任何改正。     

三分量磁通门磁变仪探头正交误差对定向的影响

本文分析了磁通门磁变仪探头三分量正交度误差对定向的影响并提出了减小其影响的措施。     

水介质对水下目标体磁场的影响

根据扬子江航道上一系列磁测及验证结果,指出在不同介质中的相似磁性物体所引起的磁场强度会产生一定的变化,实例说明：这一现象可能对磁法勘查带来的影响.文章没有对不同介质中磁性体磁场的变化机制进行讨论.     

磁偶极子梯度张量的几何不变量及其应用

磁梯度张量系统姿态的变化将影响梯度场测量和数据解释的精度,使得具有坐标变换不变性特点的张量不变量成为磁梯度张量数据解释的研究热点.本文在对磁偶极子产生的磁梯度张量进行特征值分析的基础上得到了:测量点与磁偶极子位置形成的位置矢量、磁偶极子磁矩矢量与绝对值最小的特征值对应的特征向量垂直;位置矢量和磁矩矢量与最大及最小特征值对应的特征向量共面,且两矢量间的夹角可由磁梯度张量矩阵的特征值表示.最后,将本文所得磁偶极子梯度张量的几何不变量用于磁性目标的跟踪中,取得了较好的实时跟踪效果.     

Magnetic diffusion and the motion of field lines

Diffusion of a magnetic field through a plasma is discussed in one-, two- and three-dimensional configurations, together with the possibility of describing such diffusion in terms of a magnetic flux velocity, which, when it exists, is in general non-unique. Physically useful definitions of such a velocity include doing so in terms of the energy flow or in such a way that it vanishes in a steady state. Straight field lines (or plane flux surfaces) diffuse as if flux is disappearing at a neutral sheet, whereas circular field lines (or cylindrical flux surfaces) do so as if flux is disappearing at an 0-type neutral line. In three dimensions it is not always possible to define a flux velocity, for example when the magnetic flux through a closed field line is changing in time. However, in at least some such cases it is possible to describe the behaviour of the magnetic field in terms of a pair of quasi-flux-velocities.     

Stability of the line preserving flows

We examine the equations that are used to describe flows which preserve field lines. We study what happens if we introduce perturbations to the governing equations. The stability of the line preserving flows in the case of the magneto-fluids permeated by magnetic fields is strictly connected to the non-null magnetic reconnection processes. In most of our study we use the Euler potential representation of the external magnetic field. We provide general expressions for the perturbations of the Euler potentials that describe the magnetic field. Similarly, we provide expressions for the case of steady flow as well as we obtain certain conditions required for the stability of the flow. In addition, for steady flows we formulate conditions under which the perturbations of the external field are negligible and the field may be described by its initial unperturbed form. Then we consider the flow equation that transforms quantities from the laboratory coordinate system to the related external field coordinate system. We introduce perturbations to the equation and obtain its simplified versions for the case of a steady flow. For a given system, use of this method allows us to simplify the considerations provided that some part of the system may be described as a perturbation. Next, to study regions favourable for the magnetic reconnection to occur we introduce a deviation vector to the basic line preserving flows condition equation. We provide expressions of the vector for some simplifying cases. This method allows us to examine if given perturbations either stabilise the system or induce magnetic reconnection. To illustrate some of our results we study two examples, namely a simple laboratory plasma flow and a simple planetary magnetosphere model.     

Kinematic reconnection at a magnetic null point: spine-aligned current

Magnetic reconnection at a three-dimensional null point is the natural extension of the familiar two-dimensional X-point reconnection. A model is set up here for reconnection at a spiral null point, by solving the kinematic, steady, resistive magnetohydrodynamic equations in its vicinity. A steady magnetic field is assumed, as well as the existence of a localised diffusion region surrounding the null point. Outside the diffusion region the plasma and magnetic field move ideally. Particular attention is focussed on the way that the magnetic flux changes its connections as a result of the reconnection. The resultant plasma flows are found to be rotational in nature, as is the change in connections of the magnetic field lines.     

A note on magnetic modelling with remanence

The general problem of magnetic modelling involves accounting for the effect of both remanent magnetization and the application of an external magnetic field. However, as far as the disturbing field of a magnetic body in a magnetic environment is concerned, there is an equivalence between the effects of these two causations that allows the remanence to be represented in terms of an equivalent primary magnetic H field. Moreover, due to the linearity of the magnetic field in terms of its causations, the general modelling problem involving an applied magnetic field in the presence of remanence can be simply and more efficiently dealt with in terms of an equivalent primary field acting in the absence of any remanent magnetization.     

我国磁法勘探的研究与进展

简要概述了我国磁法勘探50年来的研究与进展，主要包括：地面、航空与海洋磁测工作，磁力仪研制与生产，磁异常处理与转换技术，磁异常解释理论与方法，岩石磁性研究，磁法勘探在基础地质研究、固体矿产勘查、油气勘查和其他领域中的应用．     

低轨磁测卫星干扰磁场标定方法研究

为了提高空间磁场探测精度,磁测卫星一般将磁强计安装在长伸杆的顶端,同时通过整星磁洁净控制,来减小磁强计安装位置的磁场干扰量.针对低轨磁测卫星的特点,提出零磁场环境下卫星极弱干扰磁场的高精度测量方法,模拟在轨地磁场环境下卫星感应磁场的标定方法,以及磁力矩器剩磁不确定量的处理方法.通过以上方法对卫星本体产生的干扰磁场实施严格的标定和数据修正,可有效减小其影响,极大提升空间磁场探测精度.该方法已应用于电磁监测卫星,将整星的磁场干扰不确定量降低一个量级,达到优于0.3 nT的水平.     

Small-scale magnetic buoyancy and magnetic pumping effects in a turbulent convection

We determine the nonlinear drift velocities of the mean magnetic field and nonlinear turbulent magnetic diffusion in a turbulent convection. We show that the nonlinear drift velocities are caused by three kinds of the inhomogeneities; i.e., inhomogeneous turbulence, the nonuniform fluid density and the nonuniform turbulent heat flux. The inhomogeneous turbulence results in the well-known turbulent diamagnetic and paramagnetic velocities. The nonlinear drift velocities of the mean magnetic field cause the small-scale magnetic buoyancy and magnetic pumping effects in the turbulent convection. These phenomena are different from the large-scale magnetic buoyancy and magnetic pumping effects which are due to the effect of the mean magnetic field on the large-scale density stratified fluid flow. The small-scale magnetic buoyancy and magnetic pumping can be stronger than these large-scale effects when the mean magnetic field is smaller than the equipartition field. We discuss the small-scale magnetic buoyancy and magnetic pumping effects in the context of the solar and stellar turbulent convection. We demonstrate also that the nonlinear turbulent magnetic diffusion in the turbulent convection is anisotropic even for a weak mean magnetic field. In particular, it is enhanced in the radial direction. The magnetic fluctuations due to the small-scale dynamo increase the turbulent magnetic diffusion of the toroidal component of the mean magnetic field, while they do not affect the turbulent magnetic diffusion of the poloidal field.