Ampere Force Research Articles

Simulation of Distributed Current Sensor Based on Optical Fiber Deformation

Due to the development of automation and control systems, methods and devices for measuring of electric current large values are of great interest. The aim of the work was to develop a schematic diagram of a distributed current strength sensor based on the Brillouin optical frequency domain analysis; to create a mathematical model of the sensor to demonstrate its work and to calculate the basic parameters of the sensor. To provide the measurement optical fiber with conductive coating is used. Between the current bus, where current is measured, and conductive coating the Ampere force arises. Strain occurs in optical fiber due to this force. Stimulated Brillouin scattering has the strain dependent characteristic frequency. Shift of the characteristic frequency allows to measure current in the bus. To measure the characteristic frequency and the location of its shift Brillouin optical frequency domain analysis is used.The mathematical model of sensor operation based on tree-wave model of stimulated Brillouin scattering is demonstrated. This model allows calculating intensity of optical signal in the fiber in dependence of characteristic frequency shift. Brillouin optical frequency domain analysis uses inverse Fourier transform to obtain pulse response.A schematic diagram of a distributed current sensor based on the method of Brillouin optical frequency domain analysis is presented. An a priori estimate of parameters of the measuring system was carried out on the basis of the mathematical model of stimulated Brillouing scattering in an optical fiber. The spatial resolution of the sensor when determining the length and location of fiber sections was 0.06 m. The resolution of the sensor was 0.22 kA, the maximum value of the current strength was 25 kA. Dependence of the sensor operation at different powers of the laser used was investigated. The refractive index change influence on the result of measurements was estimated.

Characteristic Analysis of the Peak Braking Force and the Critical Speed of Eddy Current Braking in a High-Speed Maglev

In the eddy current braking system of high-speed maglev, the peak braking force and the critical speed are key factors determining the performance of eddy current braking force. In this paper, the analytical formula of eddy current braking force is derived by a subdomain method considering the skin effect of the induction plate, and, subsequently, the characteristics of peak braking force and critical speed are analyzed. The analytical model is set up in a 2D Cartesian coordinate system. The Poisson equations in each subdomain are listed by treating the vector magnetic potential as a variable. By combining the boundary conditions between two adjacent subdomains, the expressions of eddy current density and magnetic density in the induction plate are obtained. Then, the analytical formula of the eddy current braking force is obtained by the Ampere force formula. The results of finite-element analysis confirm the validity of the analytical calculation. The methods of improving the performance of eddy current braking force under high speed are proposed by parametric analysis of peak braking force and critical speed, which provides guidance for the design of the eddy current braking system in high-speed maglev.

Contextualização e tradução do artigo “Demonstração dos teoremas relativos às ações Eletrodinâmicas”, escrito por J. Bertrand.

J. Bertrand costuma ser conhecido por suas contribuições para a mecânica e para a matemática, mas pouco se sabe sobre sua predileção para a eletrodinâmica. Assim, de maneira inédita, apresentamos a contextualização e a tradução comentada, do francês para o português, do artigo “Demonstração dos teoremas relativos às ações eletrodinâmicas”. Nesse artigo, Bertrand deduz catorze teoremas fundamentais da eletrodinâmica. Entre outros pontos, tece considerações a respeito da validade da 3a lei de Newton na eletrodinâmica, deduz a Força de Ampère de apenas dois fatos experimentais – diminuindo o número dos casos de equilíbrio necessários de quatro para dois – obtém o teorema equivalente ao divergente do campo magnético (uma das equações de Maxwell), faz considerações sobre o potencial eletrodinâmico, e deduz a relação entre um dipolo magnético e um circuito fechado plano.

Magnetohydrodynamic Principle of 3D Printing for Non-Ferrous Metal Melts

In this paper, we propose a new principle of high-performance 3D printing for non-ferrous metal melts. The crystallization temperature may increase in the lower part of the tapering jet of liquid metal due to the pressure produced by the Ampere forces caused by a specially applied current. The fundamental possibility of this crystallization with regard to additional heating produced by this current was studied. The introduction of ferromagnetic additives was found to allow creating a range of parameters in which such crystallization is possible.

Mechanisms of the Formation of an Electric Arc of a Helical Shape in an External Axial Magnetic Field

A numerical simulation of an open direct-current arc in an external uniform axial magnetic field is performed. A circuit analog of fluctuations of the temperature of electrons is used for the numerical implementation of the open electric arc column of a helical shape. It randomly generates asymmetry in the temperature distribution of electrons and, consequently, other plasma characteristics. It is shown that the formation of the arc column of a helical shape is due to the asymmetric influence of the Ampere force, which shifts the cross sections of the arc relative to the central discharge axis. Furthermore, the cross sections of the arc rotate around the central axis at different speeds. The rotational speed at the initial part from the side of the cathode decreases downstream and increases upon approaching the anode. Such a character of the convective heat transfer causes the formation of a helical arc. If the direction of the external axial magnetic field coincides with the direction of the electric current, then the spatial orientation of the helical arc as a whole is right-handed. Otherwise, there is a left-handed structure of the arc column. The directions of rotation of the arc sections at the cathode and anode sides are opposite each other. A helical shape of the open arc is not constant in time and is periodically destroyed. Two modes of destruction were revealed: first, as a result of bridging the spiral of the helix and, second, as a result of the transformation of several spirals into one. Apparently, an open arc cannot maintain a stable and constant helical shape in an external axial magnetic field.

Stabilizing the Motion of a Low-Orbit Electrodynamic Tether System

This paper considers the motion of a low-orbit electrodynamic tether system designed to raise the orbit of a small spacecraft or nanosatellites. The system operates in the thrust generation mode. The orbit is raised by the Ampere force resulting from the interaction of the conducting tether with the Earth’s magnetic field. The mathematical model of motion is constructed using the Lagrange method taking into account the effect of the distributed loads from the Ampere force and the aerodynamic forces on the tether. It is shown that the motion of the system relative to the center of mass is unstable if the current is constant. It is proposed to use a linear regulator to stabilize the motion of the system with respect to the local vertical. Bellman’s dynamic programming principle is used to synthesize the regulator.

Application and Design of a Resistive-Type Superconducting Fault Current Limiter for Efficient Protection of a DC Microgrid

Regarding a dc microgrid integrated with wind, photovoltaic generators, and energy storage, this paper suggests a resistive-type superconducting fault current limiter (SFCL) to protect it from short-circuit fault. The modeling and control of the dc microgrid are first stated, and then, the resistive SFCL's impacts on the dc microgrid's fault current and bus voltage sag are analyzed in brief. Using MATLAB, simulations on different SFCL parameters are done, and the results confirm the SFCL's contributions for the dc microgrid include the following. First, the dc fault current is limited quickly and effectively. Second, the bus voltage drop is compensated enough to ensure that the renewable sources achieve the fault ride-through operation. Third, the power transfer efficiency of the dc microgrid under the fault is appropriately enhanced. Finally, the resistive SFCL's conceptual design is done. Not only is the magnetic field/current density distribution of the HTS tape given, but the Ampere Force and ac loss are also estimated. In summary, the feasibility of the resistive SFCL for the dc microgrid is verified.

Electromagnetic Analysis of the Updated Fast Control Coil for EAST

Fast control coil is one of the most important components for EAST device to control the vertical stability of plasma. However, once the heating power of EAST is updated to 36 MW, fast control coil doesn't adapt to the new operation state and couldn't provide effective control for plasma vertical instability. Thus, insulation material with ITER-like magnesium oxide is developed to withstand high radiation and the coil position is also relocated to obtain more effective instability control. Given the relocation of fast control coil, electromagnetic load acting on coil-self and feeders are calculated based on elliptical integral and Ampere force law. The electromagnetic load as volumetric force is interpolated into the finite element analysis model to analyze the stress state on fast control coil. Finally, the design-by-analysis method is adopted to evaluate whether the stress could satisfy the specified acceptance criteria. The study will provide theoretical reference for the update of fast control coil from the perspective of electromagnetic load.

Electromagnetic Modeling and Structure Optimization of a Spherical Force Sensing System.

Force sensing system (FSS) is widely used to simulate the control force of aircrafts for pilots. Conventional FSS employs multiple single-axis motors and complex transmission mechanisms to achieve multiple degree-of-freedom (DOF) force output of joystick, which may cause mismatched inertia and affect the output performance of FSS significantly. Therefore, one novel FSS with multiple DOF direct-drive spherical actuator is proposed in this paper to reduce the simulator’s extra inertia. To analyze its output performance systematically, a hybrid modeling method is proposed to formulate both Ampere torque and cogging torque mathematically. Equivalent current method along with Ampere force law is used to obtain the Ampere torque due to irregular structure of magnet and coil poles. The cogging torque is then obtained from airgap flux density via Maxwell stress method. From the derived analytical model, an adaptive particle swarm optimization (PSO) algorithm based on expectation (the average value of minimum errors) is proposed for multiple-parameter structure optimization. It can avoid local optimization effectively. The study shows that the optimized value greatly helps to improve the torque generation. Then, one research prototype and one testbed is developed. The comparison between experimental result and analytical model shows that the two sets of data fit with each other well. Therefore, the analytical model could be employed for motion control of the system at the next stage.

An Improved Model for Calculating the Magnetic Field of the Scattering of a Power Transformer Under the Action of Quasi-Constant Currents

A logically simple and quick way of calculating the instantaneous values of the magnetic field in the transformer volume when quasi-constant currents flow in the windings is suggested. To reduce the calculation time, the conductors of windings having a rectangular cross section are replaced by a set of identical circular conductors, which also fill the cross section. It allows you to use analytical expressions. From the values of the components of the magnetic induction vector at the nodes of the uniform grid the matrices are formed for each winding calculated at a single current. In calculating the instantaneous distributions of the magnetic field, the matrices are multiplied by the instantaneous currents in these windings and are summed. The calculations of the distribution of the magnetic field and the Ampere forces in a power transformer of the type TDC - 400000/220 are performed. The calculation results are presented for a quasi-constant current of a 100 A value in high-voltage winding and for its absence. It is shown that under quasi-constant current the pattern of the magnetic field distribution substantially changes and a significant increase in Ampere forces occurs. The calculation model allows you to overcome the difficulties associated with the temporary resources of the computer, and conduct a detailed study of the distribution of the stray magnetic field in the windings.

The influence of hybrid arc coupling mechanism on GMAW arc in VPPA-GMAW hybrid welding of aluminum alloys

In this study, the hybrid arc shape, thermal cycling curve, voltage-current characteristics, and weld formation of 7A52 high-strength armor aluminum alloys welded by a variable polarity plasma arc (VPPA) combined with gas metal arc welding (GMAW) (VPPA-GMAW) were investigated and compared with those of 7A52 aluminum alloys welded by GMAW. The influence of the hybrid arc coupling mechanism on the GMAW arc was studied. The results show that the electromagnetic coupling of the VPPA-GMAW hybrid arc has a dynamic compression effect on the GMAW arc. The GMAW arc is compressed parallel to the axis of the welding direction during the VPPA direct current electrode negative (DCEN) period. In addition to the ampere force of the hybrid arc magnetic field, the GMAW arc is also subjected to the hot extrusion of the hybrid arc’s coupling zone, and the arc shrinkage is greater during the direct current electrode positive (DCEP) period. With increasing VPPA current, the compression effect of the GMAW arc is enhanced. An 11-mm-thick 7A52 aluminum alloy is one-sided welded by cooperative control of the hybrid arc welding parameters.

Optical fiber ocean bottom vector magnetometer array

An optical fiber ocean bottom vector magnetometer (OOBVM) array based on fiber laser sensing technology is proposed. The fiber laser is modulated at the natural frequency of the sensing structure by the Ampere force in the magnetic field. In this way, the sensitivity is enhanced and the effect of power fluctuation of fiber laser is eliminated. The test result shows that its magnetic field resolution is about 0.86 nT / √ Hz@100 mA. The design and assembly process of the OOBVM array are demonstrated. A field test in South China Sea demonstrated that the OOBVM array can detect the movement of ferromagnetic objects in water, which implies the potential for applications in underwater object detection and marine geophysics.

Modeling and Simulation of the Magnetic Method for High Voltage Direct Current Inspection Robot

In order to solve the slipping problem of a two-arm-wheel combined inspection robot, a maglev system based on the magnetic field of a high voltage direct current (HVDC) is proposed. The magnetic system comprises of two parts: a magnetic levitation system and a magnetic drive system. The levitation component overcomes the gravity of the robot by the Ampere force generated by current-carrying coils in the magnetic field of HVDC. The drive component utilizes the Ampere force generated by current-carrying coils in the magnetic field of HVDC as the driving force. Simulation results of the model are compared with the calculated values. The results show that the magnetic levitation method and the magnetic drive method are theoretically feasible, and the model is accurate and effective, which is of great practical significance to the physical realization of the inspection robot.

Effect of electric-magnetic compound field on the pore distribution in laser cladding process

The porosity defect and the inhomogeneous pore distribution are intractable problems in the conventional laser cladding process and the laser melting porous metal separately. Therefore, it is necessary to develop a common approach to achieve the rational distribution of pores for different manufacturing processes. In this paper, electric-magnetic compound field has been applied to change the stress state of pores in the molten pool which obviously influenced the overflow speed of pores. In experiments, the laser cladding powder containing 92% AISI 316L and 8% TiH2 was adopted to obtain stable pore distribution. Results of experiments indicated that both the porosity and the pore size decreased and the pore distribution converged on the surface of the cladding layer when downward Ampere force was applied. Also an increasing tendency of porosity was observed and the pore distribution was more uniform when upward Ampere force was applied. The porosity decreased by 64.71% when the substrate current was 120 A while it increased by 144% when the substrate current was −90 A. The change of cladding shapes, microstructure and Vickers hardness of cladding layers under different Ampere force was also expounded.

Energy of Plasma Flows Accelerated in a Current Sheet as a Function of the Current Flowing through the Sheet

The energy of directed plasma flows accelerated in a current sheet is studied experimentally as a function of the current flowing through the sheet. It is found that the plasma flow energy rapidly increases with increasing current amplitude, nearly according to a power law with an exponent of 1.8–1.9. Using relations for the neutral current sheet and the concept of plasma acceleration under action of the Ampere forces, the energy of directed plasma flows is estimated as a function of the total current flowing through the sheet. It is shown that, as the current rises, the ion energy grows due to an increase in both the Ampere forces and the width of the current sheet within which plasma is accelerated.

Studies on the features of characteristic resistance of a no-insulation superconducting coil in energizing and de-energizing processes

A coil wound with no-insulation (NI) winding technique can present enhanced electrical/thermal stability and more compact structure but poorer energizing/de-energizing instantaneity as compared to an insulated counterpart. The above features of a NI coil are resulted from its turn-to-turn contact resistance, namely, the characteristic resistance Rc. Rc is a rather important parameter of a NI coil, and it is greatly influenced by winding tension, more intrinsically, the compactness of coil winding pack. Alone with the winding tension, Ampere's force that is induced by coil current and magnetic flux density, may also apply on each turn of a NI coil to influence the compactness of coil winding pack, and further the Rc and electrical behaviors of the coil. This paper explores the aforementioned influences caused by Ampere's force through energizing and de-energizing tests. Experimental results show the Rc decreases as charging current increases. Meanwhile, simulation results indicate the Ampere's force applied on each coil turn has a compressive effect and the force is proportional to the square of charging current. Furthermore, a step-rising energizing method together with a modified circuit model are proposed to calculate instantaneous current-dependent Rc. And precise prediction of coil electrical behavior is acquired. Totally, the Ampere's force do have influence on coil electrical behavior especially when the operation current and flux density are large.

NUMERICAL ESTIMATES OF ELECTRODYNAMICS PROCESSES IN THE INDUCTOR SYSTEM WITH AN ATTRACTIVE SCREEN AND A FLAT RECTANGULAR SOLENOID

Purpose. To carry out numerical estimates of currents and forces in the investigated inductor system with an attractive screen (ISAS) and determine the effectiveness of the force attraction. Methodology. The calculated relationships and graphical constructions were obtained using the initial data of the system: induced current in the screen and sheet metal; the distributed force of attraction (Ampere force); the repulsive force acting on the sheet metal (Lorentz force); amplitude values of the force of attraction and repulsion; phase dependence of the force of attraction, the repulsive force and the total resulting force. Results. The results of calculations in the form of graphical dependencies of electrodynamic processes in the region under the conductors of a rectangular solenoid of inductor system with an attracting screen are presented. The graphs of forces and currents in region of dent are obtained. In the paper the analysis of electrodynamics processes for whole area under the winding of inductor system with an attractive screen is shown. The flowing this processes in the region of dent a given geometry is presented. Originality. The considered inductor system with an attractive screen and a rectangular solenoid is improved, in comparison with the previous developed ISAS. It has a working area under the lines of parallel conductors in the cross section of a rectangular solenoid, and this allows to place a predetermined portion of the sheet metal anywhere within the working region. Comparison of the indicators of electrodynamics processes in the considered variants of calculation shows an approximate growth of almost 1.5 times the power indicators in the area of the accepted dent in comparison with similar values for the entire area under the winding of the ISAS. Practical value. The results obtained are important for the practice of real estimates of the excited forces of attraction. With a decrease in the dent, the amplitude of the electrodynamics forces being excited is growing proportionally (for example, when the depth decreases by 3 mm, the forces increase more than 2 times). The highest efficiency of force attraction is for sheet metal regions, the dimensions do not exceed the transverse dimensions of the winding branches of the exciting solenoid.

Repeated Sparks Produce Free Energy: A Rigorous Mathematical Explanation of the Authors, by the Hidden Ampere Force Law

This is the twinned paper of the increased mass paper, “Gravity is acting at superluminous infinite speed, thus collapsing special theory of relativity of Einstein, an explanation for almost everything (according to the authors’ rigorous mathematical proof and overwhelming experimental evidence)" [1]. In the present paper, we describe the repeated spark or repeat current in terms of the hidden, Non-Relativistic Longitudinal Cardinal Ampere Force which is not found yet infallible for every case. The impressive finding is the fact that these repeated sparks as we shall see, have no back-emf, but forward-emf and forward-Ampere-motive-force. The only consumption is the resistive load with the very high currents needed. This means its total energy consumption is less than the released energy-output work plus heat, plus the energy recharging the batteries. All these are in excess of the consumed input energy. This means the Repeated sparking is “over-unity” efficiency and that, using super-conductive materials, we shall have constructed the first “perpetual mobile” plus producing extra electrical energy. Several previous journals that we did not mention here their names did not dare to publish our disliked papers of very important and revolutionary results but were not able to counter argue our arguments. They preferred the silence and have not answered us at all for many years now. Even some of them were involved previously with the repeated sparking which is the same topic of our present paper.

Model of Solar Wind in the Heliosphere at Low and High Latitudes

The spatial distributions of the magnetic field, plasma density, and current at distances of (20–400)RS from the Sun (where RS is the solar radius) are investigated within a stationary axisymmetric MHD model of the solar wind (SW) at all latitudes in the inertial frame of reference with the origin at the center of the Sun. The model takes into account differential (with respect to the heliolatitude) rotation of the Sun and full corotation of plasma inside a boundary sphere of radius 20RS, which breaks down beyond this sphere. Self-consistent distributions of the plasma density, current, and magnetic field in the SW are obtained by numerically solving a set of time-independent MHD equations in spherical coordinates. It is demonstrated that the calculated results do not contradict observational data and describe a gradual transition from the fast SW at high heliolatitudes to the slow SW at low heliolatitudes, as well as the steepening of the profiles of the main SW characteristics with increasing distance from the Sun. The obtained dependences extend understanding of the SW structure at low and high latitudes and agree with the well-known Parker model in the limit of a small Ampere force.

创新型物理实验设计与学生能力培养研究—以安培力实验创新为例

创新型物理实验设计与学生能力培养研究—以安培力实验创新为例