Magnetic Generation Research Articles

Comparative simulation of switching regimes of magnetic explosion generators by copper and aluminum magnetodynamic current breakers taking into account elastoplastic properties of materials

We report on the results of the computer simulation of the operation of magnetodynamic break switches used as the second stage of current pulse formation in magnetic explosion generators. The simulation was carried out under the conditions when the magnetic field energy density on the surface of the switching conductor as a function of the current through it was close to but still did not exceed the critical value typical of the beginning of electric explosion. In the computational model, we used the parameters of experimentally tested sample of a coil magnetic explosion generator that can store energy of up to 2.7 MJ in the inductive storage circuit and equipped with a primary explosion stage of the current pulse formation. It has been shown that the choice of the switching conductor material, as well as its elastoplastic properties, considerably affects the breaker speed. Comparative results of computer simulation for copper and aluminum have been considered.

Smartphones and Programmable Shunts: Are These Indispensable Phones Safe and Smart?

This study aimed to determine whether smartphones affect programmable shunts. iPhone 5S (Apple Inc., Cupertino, CA, USA) and Samsung Galaxy S5 (Samsung Electronics, Gumi, South Korea) smartphones were chosen for this study. For both phones, magnetic field mapping was performed with 3-dimensional magnetic scanning systems constructed with high-precision motorized stages, and a Hall effect sensor was used to measure the flux density on the smartphone surface. The distance (h) between the distal outlet of the reservoir and the rugby ball of the Strata valve (Medtronic Inc., Minneapolis, MN, USA) was measured using highly sensitive microanalysis optical method. During optical microanalysis, while keeping a 3-cm distance between the valve and the magnetic generator, the h value (μm) was recorded for different magnetic flux densities (MFDs). Then, direct x-ray radiography was performed for radiologic assessment after each process under different magnetic fields. For analysis of the Codman Certas valve (Codman Neuro, Raynham, MA, USA), the magnet orientation and the angle between the magnet with the tantalum ball were measured with the same optical analysis. Maximum MFDs found 62 G for iPhone 5S and 61 G for Samsung Galaxy S5. When the magnetic generator formed a current at 0, 30, 60, and 90 G, the h values of the Strata valve adjusted to 100 mm H2O opening pressure were 320, 280, 190, and 175 μm, respectively. When the magnetic generator was removed from the environment, the h value returned to 320 μm. In direct graphs taken after each optical analysis at different Gauss values, substitution was not observed at the indicator. The angle in the Codman Certas valve was 123.9°, 112.5°, and 103.6° at the magnetic flux densities of 0, 60, and 90 G, respectively. When the magnetic field was removed (0 G), the angle was still 103.6°, suggesting an irreversible effect in the shunt construct. Smartphones exert reversible effects on Strata programmable valves without producing remarkable radiologic findings and irreversible effects on Codman Certas valves.

The Theory of the Development of an Electromagnetic Engine for Automotive Use

The need to reduce the emission emitted from IC engine powered vehicle is paramount, as Malaysia has pledged to reduce 40% of CO2 intensity by 2020 from 2005 level by 25% improvement in average fuel consumption. The introduction of Electromagnetic Engine (EE) is one of the initiatives, however the electromagnetic engine could face several weaknesses amongst which are: limited driving range, thermal control, charging infrastructure, and overall limited efficiency. This study presents an electromagnetic propulsion system for automotive use that has a total different operating sequence compared to IC engines. It works by the principle of magnetic attraction and repulsion between electromagnet and a permanent magnet. The power supply interruption made by means of the reed switch to move down the piston. Thus, the back-and-forth movement of the piston occurs without failure. The experiment has been conducted on the determination of the electromagnetic engine performance by varying the applied loads on the crankshaft. The efficiency has been found of the model EME in the range of 12-20%. However, it could be achieved about 40-45% by proper sealing the magnetic flux of the electromagnet and alignment, exact fitting the piston and cylinder and prevent the magnetic flux leaking and heat generation, and the development

Magnetic flux analysis and performance test of permanent magnet and claw-pole electromagnetic hybrid excitation generator for electric vehicle range extender

Developed hybrid excitation generator (HEG) has a tangential permanent magnet (PM) and claw-pole electromagnetic parallel combined rotor and a fractional-slot winding stator, which makes stator core eddy-loss and armature winding copper-loss less. By establishing the equivalent magnetic circuit model of each part of HEG and analysing permeance influence factors, magnetic isolation measures are taken to reduce flux leakage and improve output efficiency. The designed electromagnetic coupling regulator controller can ensure stable voltage export of HEG in a wide range of speeds and load states by changing quantity and direction of excitation current to adjust the size of air gap magnetic flux density. Performance test is done and results show that the output voltage is relatively stable. So the HEG can provide electric energy to battery and electrical equipment of vehicles.

Generation of Electromagnetic Energy in a Magnetic Cumulation Generator with the use of Inductively Coupled Circuits with a Variable Coupling Coefficient

Generation of Electromagnetic Energy in a Magnetic Cumulation Generator with the use of Inductively Coupled Circuits with a Variable Coupling Coefficient

A mobile test facility based on a magnetic cumulative generator to study the stability of the power plants under impact of lightning currents

The report presents the results of the development and field testing of a mobile test facility based on a helical magnetic cumulative generator (MCGTF). The system is designed for full-scale modeling of lightning currents to study the safety of power plants of any type, including nuclear power plants. Advanced technologies of high-energy physics for solving both engineering and applied problems underlie this pilot project. The energy from the magnetic cumulative generator (MCG) is transferred to a high-impedance load with high efficiency of more than 50% using pulse transformer coupling. Modeling of the dynamics of the MEG that operates in a circuit with lumped parameters allows one to apply the law of inductance output during operation of the MCG, thus providing the required front of the current pulse in the load without using any switches. The results of field testing of the MCGTF are presented for both the ground loop and the model load. The ground loop generates a load resistance of 2–4 Ω. In the tests, the ohmic resistance of the model load is 10 Ω. It is shown that the current pulse parameters recorded in the resistive-inductive load are close to the calculated values.

Nonlinear-optical study of magnetoelectric interactions in multilayer structures

ABSTRACTTemperature dependences of electric field-induced and magnetic field-induced optical second harmonic generation (SHG) were used to study La0.7Ca0.25MnO3/BaTiO3 (LCMO/BTO) superlattice. Ferroic properties of the superlattice are reveal by magnetic field-induced and electric field-induced SHG hysteresis loops (“magnetic” and “electric” SHG loops). However, direct modifications of the SHG hysteresis loops by the other field (electric field for the “magnetic loop” and vice versa) were not found. Strong modifications of the “electric” SHG hysteresis loops occur at temperatures close to the paramagnetic-ferromagnetic and the insulator-metal phase transitions in LCMO. In this way, the magnetoelectric interaction in an LCMO/BTO superlattice was established indirectly.

Dufour and Soret Effects on MHD Forced Convective Heat and Mass Transfer Flow of Non-Newtonian Power Law Fluid with Thermal Radiation and Viscous Dissipation

This paper investigates the Dufour and Soret effects of forced convection heat and mass transfer of an electrically conducting, non-Newtonian power-law fluid past a stretching sheet under the simultaneous action of suction, radiation, uniform transverse magnetic field, heat generation and viscous dissipation. The stretching sheet is assumed to continuously moving with a power-law velocity and maintaining a uniform surface heat flux. The governing nonlinear partial differential equations are transformed into a system of non linear ordinary differential equations using appropriate similarity transformations. The resulting dimensionless equations are solved numerically using sixth order Runge-Kutta integration scheme with Nachtsheim-Swigert shooting iterative technique. A systematical study of numerical results for the non-dimensional velocity, temperature and concentration profiles are presented graphically. The viscous drag or local Skin-friction coefficient, heat transfer rate or local Nusselt number and mass transfer rate or local Sherwood number are represented in tabular and graphical forms to illustrate the details of flow characteristics and their dependence on all physically important parameters in case of Newtonian and non-Newtonian (pseudo-plastic and dilatants) fluids.

Design of a Bipolar Magnetic Pulse Generator and Experimental Study on Its Anti-scaling Effect

Design of a Bipolar Magnetic Pulse Generator and Experimental Study on Its Anti-scaling Effect

Preferential Magnetic Flux Invasion and Heat Generation Owing to Macrostructure in HTS Bulk Magnets in Pulse Field Magnetization Processes

In order to clarify the behavior of the magnetic flux that invade into the melt-processed Dy123-based high-temperature superconducting bulk magnet, the motions of magnetic fluxes and the phenomena of heat generation were precisely measured during the pulsed field magnetization processes. In the experiments, we estimated the time evolutional profiles that were measured at two portions in the growth sector region and the growth sector boundary. They are characterized as the areas of lower and higher critical current densities than each other, respectively. The serial pulsed magnetic fields of 5 T were applied to the sample at 30 K, and the data were obtained in turn by the Hall sensor and thermometer that were put at several positions along the radial rows on the growth sector boundary and the growth sector region. The profiles of magnetic flux during the pulsed field application actually proved that the magnetic flux invades the sample through the growth sector regions in shorter time and with stronger magnitude than through the growth sector boundaries. Since the low magnetic field application leads to low heat generation, it is expected to achieve the higher trapped field performances than ever.

Nanosecond Megavolt Charging of Forming Lines by Explosive MCGs

A new design of powerful high-voltage high-current impulse source for nanosecond megavolt charging of short forming lines (SFLs) is proposed. The first stage of the device is based on inductive energy storage. It accumulates energy supplied by the current of magnetic flux compression generator (MCG), whereas the electro-explosive opening switch is used for the energy output into intermediate SFL. In the second stage, we use a Tesla transformer with oil insulation. The results of the earlier experimental study of submegavolt charging of intermediate forming line as well as the results of calculations of the two-stage facility given in this paper demonstrate the feasibility of the device based on MCGs for nanosecond charging of SFL up to about 3 MV.

Radiation hazards in PF-1000 plasma generator fusion research (part 2)

This paper focuses on radiation exposures to researchers and technicians involved in fusion research. It is the second article in the series on this topic. It discusses immediate exposures to the ionizing radiation that is generated immediately during fusion research performed on the PF-1000, a dense magnetized plasma generator that is the world’s largest.

Radiation hazards in PF-1000 plasma generator fusion research

Fusion research poses significant radiation hazards, including prompt as well as delayed exposures. Prompt radiation consists of deeply penetrating neutrons and gamma rays, whereas delayed exposure derives from nuclear decays that were previously activated by neutrons. The PF-1000 plasma focus device, a dense magnetized plasma generator, is a source of all of these radiation hazards. The aim here is to assess the delayed radiation hazard of the PF-1000 device to the operational crew and research scientists.

Experimental Evaluation of a Variable Shear Modulus Characteristic for Magnetorheological Elastomer Due to Induced Current

Abstract The purpose of this study is to fabricate an anisotropic magnetorheological elastomer (MREs) based on natural rubber (NR) that has a more advanced MR effect than isotropic MREs by using an anisotropic mold. We evaluated variation in the shear modulus of the MREs in the frequency domain under a magnetic field with a continuously-variable induced current. An evaluation system is proposed that includes a magnetic flux generator, which generates a magnetic field via a continuously-variable induced current. One of the anisotropic MREs possessing 30 vol. %, 40 vol. %, and 50 vol. % carbonyl iron powder was expected to have the highest shear modulus variation as a function of the variable induced current. With the evaluation system, we identified the variation and maximum variation rate of the shear modulus of MREs with three different volume fractions of carbonyl iron powder (CIP) and continuously-variable induced current. The magnetic flux density generated by the magnetic flux generator (MFG) is optimized by electromagnetic finite element method (FEM) analysis and response surface method techniques. The values of each design factor determined by the response surface method (RSM) were applied to the redesign of the evaluation system, including the MFG. The proposed system is verified for the range in which MFG can generate magnetic flux density in order to determine the existence of magnetic saturation of the MFG by magnetic circuit analysis. Consequently, the appropriate volume fraction of CIP in MREs without inducing currents can be determined for any desired shear modulus. The desired volume fraction of CIP in the anisotropic MREs can be approximated to achieve an appropriate shear modulus variation rate. This study demonstrates that it is possible to obtain an appropriate volume fraction of CIP and induced current to achieve the desired shear modulus variation rate of an anisotropic MRE.

Conversion of high explosive chemical energy into energy of powerful nanosecond high-current pulses

This study is a contribution into the development of physicotechnical foundations for generation of powerful nanosecond high-current pulses on the basis of explosively driven magnetic flux compression generators. This problem is solved by using inductive storage of energy for matching comparatively low-voltage explosively driven magnetic flux compression generators and high-impedance loads; short forming lines and vacuum diodes. Experimental data of charging of forming lines are given.

Experiments of cylindrical isentropic compression by ultrahigh magnetic field

The high Explosive Magnetic Flux Implosion Compression Generator (EMFICG) is a kind of unique high energy density dynamic technique with characters like ultrahigh pressure and low temperature rising and could be suitable as a tool of cylindrical isentropic compression. The Institute of Fluid Physics, Chinese Academy of Engineering Physics (IFP, CAEP) have developed EMFICG technique and realized cylindrical isentropic compression. In the experiments, a seed magnetic field of 5–6 Tesla were built first and compressed by a stainless steel liner which is driven by high explosive. The inner free surface velocity of sample was measured by PDV. The isentropic compression of a copper sample was verified and the isentropic pressure is over 100 GPa. The cylindrical isentropic compression process has been numerical simulated by 1D MHD code and the simulation results were compared with the experiments. Compared with the transitional X-ray flash radiograph measurement, this method will probably promote the data accuracy.

Magneto-hydrodynamic calculation of magnetic flux compression with explosion driven solid liners and analysis of quasi-isentropic process

Magnetic cumulative generator (MC-1) is a kind of high energy density dynamic device. A liner is driven by a cylinderical explosive implosion to compress the magnetic flux preset in the cavity. Then the chemical energy is converted into magnetic one, which is cumulated nearby the axis to form ultra-intense magnetic field used to load sample in non-touch manner. This loading technique can bring higher pressure and relatively low elevated temperature in the sample and has a very high-degree isentropy in the course of compression. The configuration magneto-hydrodynamic code SSS/MHD is used to develop one-dimensional magneto-hydrodynamic calculation of magnetic flux compression with explosion driven solid liner. The calculation results of magnetic field in cavity and velocity of inner wall of sample tube are obtained and accord with the magnetic field measured by probe and the velocity measured by laser interference. The buckling and Bell-Plesset instabilization produced by linerly compressing magnetic field are shown through frame photography. The change laws of magnetic diffusion, eddy current and magnetic pressure in liner and sample tube are analyzed, which show that the magnetic field and pressure and eddy near to cavity in the sample tube are all higher than the ones in the liner with the same distance to cavity. The balance between the electromagnetism force and implosion action and the difference between sample tube and liner velocities are the main reasons under imploding movement. The change of isentropic increment with compression degree at the same location, whose distance is 0.05 mm to magnetic cavity in the sample tube, is discussed. The result indicates that the ratio of the maximum increment to specific heat of sample tube material is about 10%, which shows that the process of compression magnetic flux with explosion is quasi-isentropic. In general, SSS/MHD code can reveal in depth the physic images which are difficult to measure or observe in the magneto-hydrodynamics experiment.

Dispersion Modeling and Analysis for Multilayered Open Coaxial Waveguides

This paper presents a detailed modeling and analysis regarding the dispersion characteristics of multilayered open coaxial waveguides or cables. The electromagnetic model is based on a layer recursive computation of axial-symmetric fields in connection with a magnetic frill generator excitation that can be calibrated to the current measured at the input of the cable. The layer recursive formulation enables a stable and efficient numerical computation of the related dispersion functions, as well as a detailed analysis regarding the analytic and asymptotic properties of the associated determinants. Modal contributions as well as the contribution from the associated branch-cut (nondiscrete radiating modes) are defined and analyzed. Measurements and modeling of pulse propagation on an 82-km-long HVDC power cable are presented as a concrete example. In this example, it is concluded that the contribution from the dominating axial-symmetric transverse magnetic mode is sufficient, and that the contribution from the branch-cut is negligible for all practical purposes, and in particular if the exterior domain is lossy. The main contribution of this paper is to provide the necessary modeling and analysis tools for a quantitative study of these phenomena.

Wave Propagation Characteristics and Model Uncertainties for HVDC Power Cables

This paper presents a stable and efficient full-wave cable model and a detailed study of the related model uncertainties regarding the wave propagation characteristics of very long HVDC power cables at low frequencies. The model can be used to predict the dispersion characteristics of the cable with respect to its electromagnetic parameters, or as an inverse problem to estimate some parameters of the cable (armor permeability, metal-layer conductivities, temperature, length, etc.) based on measurements. The electromagnetic model is based on a magnetic frill generator that can be calibrated to the current measured at the input of the cable, and a layer-recursive computation of the axial-symmetric fields. Measurements of pulse propagation on an 82-km-long HVDC power cable over a bandwidth of 100 kHz have been used to validate the model. The main conclusion of the study is that the conductivity (and, thus, the temperature) of the conductor and the lead sheath are of utmost importance to achieve an accurate model. At the same time, some parameters are, in principle, insignificant regarding the dispersion characteristics in the low-frequency regime, such as the permittivity and the conductivity of the semiconducting screens. This paper contains an investigation and a discussion on the electromagnetic properties of all layers of a typical HVDC power cable.

Magnetic disturbance generation during the historic magnetic storm in September 1859

The model calculation of a magnetic disturbance, which was registered at Colaba observatory (India) during the historic giant magnetic storm on September 1–2, 1859, is illustrated. The calculation demonstrates that the observed, unusually fast, 2-h main phase of this storm, when the negative amplitude of the geomagnetic field vector H component was −1600 nT, and an extremely fast (1.5-h) initial field recovery phase from the maximum to the −110 nT amplitude can be generated. The following models of the magnetospheric current systems were used in the calculations: the ring current (DR), the magnetospheric magnetopause current (DCF), the magnetotail current system (DT), and the high-latitude current system (DP). The unusual time variation in the registered geomagnetic disturbance is related to the probable fast and considerable equatorward shift of the high-latitude currents during the main phase of the analyzed giant storm and to the same fast backward motion of these currents during the initial field recovery phase. The unusually large amplitude of the registered geomagnetic disturbance could have been caused by the total contribution of the indicated magnetospheric current systems during the time when the storm was generated as a result of the interaction between the magnetosphere and the solar plasma ejected during the gigantic solar flare before the storm.