銅の電気めっきにおける磁場効果－スルーホールめっきへの応用－

Under a parallel magnetic field, after long-term copper deposition from an acidic copper sulfate solution, numerous spherical secondary nodules of 10 to 100 μm diameters were formed one upon another in dendritic mode. This is a new type of micro-magnetohydrodynamic (MHD) effect arising from the unstable growth of three-dimensional (3D) and two-dimensional (2D) nuclei by specific adsorption of hydrogen ions (second micro-MHD effect). From the viewpoint of instability in electrodeposition, though 3D nucleation in the diffusion layer is always unstable, with ionic specific adsorption such as hydrogen ions, stable 2D nucleation turns unstable after long-term deposition. The resultant competitive growth of 3D and 2D nuclei produces spherical nodules as their composite, leading to their dendritic growth. Furthermore, though negligibly small, nonequilibrium fluctuations occurring in 2D nucleation migrate with the laminar solution flow caused by Lorentz force (MHD flow). Depending on whether the ionic adsorption is specific or nonspecific, the traveling asymmetrical fluctuation changes the direction to the upstream or downstream side, respectively.

The flow of hybrid nanoparticles with significant physical parameters with different base fluids in the presence of Biot number, velocity slip, and MHD effects has not been explored so far, particularly for a circular cylinder. Therefore, the current report is presented to offer a numerical solution for hybrid nanoparticles with base fluids (water and ethylene glycerol) via a circular cylinder. The physical situation is interpreted in terms of partial differential equations and is converted into ordinary differential equations after applying the similarity transformation. The results are presented in both tabular and graphical forms. The impact of physical parameters on velocity distribution is examined through graphs. The comparative results of hybrid nanoparticles for distinct base fluids as ethylene glycol and water are proposed and the hybrid nanoparticles with base fluid water seems to be greater than that of the hybrid nanoparticles with base fluid EG. The temperature profile of hybrid nanoparticles is found to be a decreasing function with growth in velocity slip parameter but an opposite trend is noted in case of nanoparticles . The skin friction and Nusselt number augmented for the increase in magnetic field, velocity slip, and nanoparticle while it shows a decreasing trend toward thermal slip parameter. For the both cases, improvement in Biot number helps enhance the heat transfer constantly.

An analysis of the effects of MHD on a two-dimensional free-convective flow of a viscous incompressible fluid past a semi-infinite isothermal inclined plate is carried out. The effects of viscous dissipation and the induced magnetic field are assumed to be negligible. A more accurate, unconditionally stable, and fast converging implicit finite difference scheme is used to solve the dimensionless governing equations. The effects of MHD on velocity, temperature, local and average skin friction, and local and average Nusselt number are studied. It is observed that the magnetic field parameter has a retarding effect on the velocity.

Edge electrodeposition effect of cobalt under an external magnetic field

The generation of Lorentz force is limited by the local magnetic field and the relative velocity of the spacecraft. As a result of this constraint, the Lorentz force cannot completely take place of the traditional propulsion technologies. In recent years, studying the Lorentz force provided by modulating spacecraft electrostatic charge (magnetic and electric fields) has become a possible good means to control the spacecraft without fuel consumption or reduce the fuel cost. Most of the previous studies concerned the Lorentz force of the magnetic field only. In this paper, we developed a combination of Lorentz forces provided by modulating spacecraft's electrostatic charge (magnetic and electric fields) that can be used to keep the desired relative distances and orientations. We are derived nonlinear dynamic models of satellite relative motion considering J2 perturbation, and Lorentz forces to develop a mathematical model for a new technique establishing increase the level of charging in the spacecraft surface. These solutions indicate that the principal effects of the Lorentz force on a spacecraft can be used to correct the drift in the relative position of formation flying due to the effect of Second zonal harmonics, where the magnitude of charge to mass ratio is the key player for the correction of this drift. Numerical results for different examples of formation flying confirmed the capability of Lorentz force to correct the drift in relative position. These corrections depend on the value of charge to mass ratio and magnitude of the relative position.

Summary form only given, as follows. Plasma opening switches (POS) are the key components of inductive energy store (IES) pulsed power systems. In the closed phase an IES system stores magnetic energy in the inductance of a vacuum transmission line. As the POS opens the stored magnetic energy flows past the POS and into a load (for example an electron or ion diode). To achieve power multiplication the opening time should be much shorter than the conduction time. There are three proposed mechanisms that control the conduction phase of the POS: 1) sheath effects at the electrodes, 2) rapid penetration of magnetic field into the body of the plasma due to EMH effects, and 3) displacement and distortion of the plasma. due to J/spl times/B (MHD) forces. In this paper, the PIC code, MAGIC, is used to study EMH and MHD effects in a POS. These simulations were performed in negative polarity with a strong radial density gradient. In regimes where EMH is expected to be dominant, the simulations show rapid axial penetration of magnetic field into the plasma in a narrow radial channel along the positive density gradient. No field penetration is observed along the negative portion of the density gradient. In positive polarity, field penetration occurs along the negative gradient and no field penetration is observed along the positive density gradient. This agrees with EMH theory of shock penetration of magnetic field. However, the speed of penetration is somewhat slower than predicted by fluid treatments. The PIC simulations also show the formation of vortices in the electron flow behind the EMH shock front.

In this paper, both electric field and magnetic field were used to assist the hot filament chemical vapor deposition (HFCVD) and we systematically investigated the effects of which on the (1) phase composition, (2) grain size, (3) thickness and (4) preferred orientation of diamond films through SEM, Raman and XRD. The application of magnetic field in electric field, so called ‘the magnetic and electric coupling fields’, enhanced the graphitization and refinement of diamond crystals, slowed down the decrease of film thickness along with the increase of bias current, and suppressed diamond (100) orientation. During the deposition process, the electric field provided additional energy to HFCVD system and generated large number of energetic particles which might annihilate at the substrate and lose kinetic energy, while the Lorentz force, provided by magnetic field, could constrict charged particles (including electrons) to do spiral movement, which prolonged their moving path and life, thus the system energy increased. With the graphitization of diamond films intensified, the preferred orientation of diamond films completely evolved from (110) to (100), until the orientation and diamond phase disappeared, which can be attributed to (I) the distribution and concentration ratio of carbon precursors (C2H2 and CH3) and (II) graphitization sequence of diamond crystal facets. Since the electron field emission property of carbon film is sensitive to the phase composition, thickness and preferred orientation, nano- carbon cones, prepared by the negative bias current of 20 mA and magnetic field strength of 80 Gauss, exhibited the lowest turn-on field of 6.1 V −1 μm−1.

This paper deals with the effects of electromagnetic forces on the orbital motion of a spacecraft. The electrostatic charge which a spacecraft generates on its surface in the Earth's magnetic field will be subject to a perturbative Lorentz force. A model incorporating all Lorentz forces as a function of orbital elements has been developed on the basis of magnetic and electric fields. This Lorentz force can be used to modify or perturb the spacecraft's orbits. Lagrange's planetary equations in the Gauss variational form are derived using the Lorentz force as a perturbation to a Keplerian orbit. Our approach incorporates orbital inclination and the true anomaly. The numerical results of Lagrange's planetary equations for some operational satellites show that the perturbation in the orbital elements of the spacecraft is a second order perturbation for a certain value of charge. The effect of the Lorentz force due to its magnetic component is three times that of the Lorentz force due to its electric component. In addition, the numerical results confirm that the strong effects are due to the Lorentz force in a polar orbit, which is consistent with realistic physical phenomena that occur in polar orbits. The results confirm that the magnitude of the Lorentz force depends on the amount of charge. This means that we can use artificial charging to create a force to control the attitude and orbital motion of a spacecraft.

An analytical solution for the 2D distribution of the electric potential in MHD flow in a nonuniform magnetic field produced by rectilinear current is obtained. Analytical equations for the current density and the Lorentz force in the locally ionized MHD flow are obtained. It is shown that the Lorentz force distribution and thus the MHD effect on the flow significantly depend on the electric field imposed. The supersonic locally ionized MHD flow over a flat plate is calculated under different conditions. It is shown that the MHD effect allows one to significantly modify the flow pattern and the surface pressure distribution along the plate.

Overview Having shown in Chapter 5 that the magnetic force must exist, we will now study the various properties of the magnetic field and show how it can be calculated for an arbitrary (steady) current distribution. The Lorentz force gives the total force on a charged particle as F = q E + q v × B . The results from the previous chapter give us the form of the magnetic field due to a long straight wire. This form leads to Ampere’s law , which relates the line integral of the magnetic field to the current enclosed by the integration loop. It turns out that Ampere’s law holds for a wire of any shape. When supplemented with a term involving changing electric fields, this law becomes one of Maxwell’s equations (as we will see in Chapter 9). The sources of magnetic fields are currents, in contrast with the sources of electric fields, which are charges; there are no isolated magnetic charges, or monopoles . This statement is another of Maxwell’s equations. As in the electric case, the magnetic field can be obtained from a potential, but it is now a vector potential ; its curl gives the magnetic field. The Biot–Savart law allows us to calculate (in principle) the magnetic field due to any steady current distribution. One distribution that comes up often is that of a solenoid (a coil of wire), whose field is (essentially) constant inside and zero outside. This field is consistent with an Ampere’s-law calculation of the discontinuity of B across a sheet of current. By considering various special cases, we derive the Lorentz transformations of the electric and magnetic fields. The electric (or magnetic) field in one frame depends on both the electric and magnetic fields in another frame. The Hall effect arises from the q v × B part of the Lorentz force. This effect allows us, for the first time, to determine the sign of the charge carriers in a current.

When we move the Hall component in a uniform gradient magnetic field under the constant current, the Hall electromotive force it outputs depends only on the amount of its displacement in the magnetic field. According to this characteristic, this paper analyses the basic principles, the selection of uniform gradient magnetic field and the output of displacement expression data. This paper makes a research from the four aspects. With improvement and innovation, we try to design a sensor which can measure miniature vibration. Introduction Nowadays, as the deepening of the scientific research, we have become increasingly demanding for the accuracy of measurements. That, how to measure small vibrations conveniently and quickly, is a research aspect that receives much concern. Hall displacement sensor, compared with other displacement sensors, has features such as quick response, simple structure and low cost, and some disadvantages about the measurement as well. To achieve the effect small vibrations to be measured, we will improve and research the sensor, based on its disadvantages. Fundamental principles Hall effect When a magnetic field is present to the semiconductor that is perpendicular to the direction of the current, the electrons and holes inside the semiconductor will experience a force, which is called the Lorentz force, and the electrons and holes will accumulate on one face of the material, establishing an electric field. The force from the electric field opposes the Lorentz force. When the electric field reaches a certain value, the electric force and the Lorentz force experienced by the holes and electrons are balance. The electric field opposes the migration of further charge, so a steady electrical potential is established, making the subsequent electron and holes can pass without deflection. This is called the Hall effect. As is shown in the Fig.1. Suppose the conductor is a cuboid, whose length, width and height are a, b, and c respectively, the electricity flows in from surface cd vertically, and that the magnetic field intensity is B vertical to surface ab, the voltage between the two boards front and back is therefore Hall voltage Fig.1: Hall effec International Power, Electronics and Materials Engineering Conference (IPEMEC 2015) © 2015. The authors Published by Atlantis Press 969 According to the formula of Hall voltage U, with a fixed electric current I, as long as the magnetic field gradient is constant, the value of Hall voltage across the Hall element will show a positive liner relationship with its displacement within the Hall element. Hall element. Produce Hall element using the principle of Hall Effect. The performance curve of Hall element is as follows: The purpose is to find appropriate electric current and magnetic field, so that with a fixed electric current and constant magnetic field gradient, the Hall element will work with in interval AB in the phase diagram. The working status of Hall element is also associated with temperature. For the sake of measuring accuracy, SS495A1 Hall element is chosen, whose working temperature is between -40C and 150C with strong flexibility, matching the requirement of measurement and design. . Fig.2: Characteristic Choosing the magnetic field As is shown in the first step, in order to make the instrument reflect tiny vibration, a liner relationship between Hall voltage and displacement is in need. Thus, we need to select a magnetic field with constant gradient. This essay develops the study according to an experiment – correction verify procedure, fitting Hall voltage and displacement of Hall elements in magnetic field of various shapes, through which we find that magnetic field of bar magnet is pretty close. Consequently, we made further improvement based on this idea, and finally choose to fix two angel-shaped iron on the two sides of the bar. The specific measuring method is as follows: Fig.3 Measuring method Fitting this set of data using MATlAB, we have Fig.4:

Influence mechanism of magnetic field direction on magnetic drag of reentry vehicle and better magnetic field direction

Magnetic reconnection is a fundamental process that can take place in astrophysical or laboratory plasmas. It occurs within regions of large magnetic gradient where the magnetic field is no longer frozen to the plasma but instead diffuses through it, releasing magnetic energy and causing a change in the connectivity of the field lines. In particular, on the Sun, magnetic reconnection is believed to play an important role in coronal heating, X ray bright points, solar flares and canceling magnetic features. Here, an exact time‐dependent solution of the MHD equations for magnetic annihilation in response to a time‐varying stagnation point flow is presented. The main assumptions in this model are that the magnetic field lines are straight (so that there is no magnetic tension acting on the plasma) and the flow that carries the field lines together is of stagnation point type. This is a reasonable model for the resistive MHD behaviour near the X point of a reconnecting field, especially when the central diffusion region is long, as in the flux pile up regime (Priest and Forbes 1986). The general solution is used to conduct a series of numerical experiments, namely, the evolution of different initial magnetic profiles in a steady flow; the effect of a sudden change in magnetic diffusivity on an initially steady state; the effects of a velocity that either increases linearly in time or ramps up from one steady value to another. The results exhibit the effects of subtle imbalances in diffusion and advection but have the following general features: (1) a diffusion layer is created, the thickness of which is determined by the nature of the plasma flow; (2) the magnetic field outside the diffusion region is determined by advection and will either exponentially increase, exponentially decay or remain in a steady state, depending on whether the initial magnetic profile B (y) ∼ y−n has n < 1, n > 1, or n = 1, respectively; and (3) the magnetic field within the diffusion layer tends to respond to the advected magnetic field at its edge.

Heat transfer in closed channel flows of molten salts (MS)s, such as FLiBe or FLiNaBe, has been considered under specific reactor conditions. MHD effects have been accessed for two blanket concepts: self-cooled MS blanket, and dual-coolant MS blanket. The effect of heat transfer degradation due to turbulence reduction by a magnetic field in the First Wall channels of the self-cooled blanket was analyzed with the K-ε model of turbulence. In the dual-coolant blanket, the MS flow is laminar. A 2-D MHD code was used to calculate the laminar velocity profile first. Then, the temperature field was calculated using a 3-D temperature code. Reasonable interface temperatures below the material limit of 550°C, and low heat escape from the breeder zone have been demonstrated. Model limitations and the ways of their improvement are also discussed.

The generation of primordial magnetic fields from cosmological phase transitions is discussed, paying particular attention to the electroweak transition and to the various definitions of the `average' field that have been put forward. It is emphasised that only the volume average has dynamical significance as a seed for galactic dynamos. On rather general grounds of causality and energy conservation, it is shown that, in the absence of MHD effects that transfer power in the magnetic field from small to large scales, processes occurring at the electroweak transition cannot generate fields stronger than $10^{-20}$ Gauss on a scale of 0.5 Mpc. However, it is implausible that this upper bound could ever be reached, as it would require all the energy in the Universe to be turned into a magnetic field coherent at the horizon scale. Non-linear MHD effects seem therefore to be necessary if the electroweak transition is to create a primordial seed field.