Orthogonal Magnetic Field Research Articles

Electron–positron planar orbits in a constant magnetic field

The different types of orbits in the classical problem of two particles with equal masses and opposite charges on a plane under the influence of a constant orthogonal magnetic field are classified. The equations of the system are reduced to the problem of a Coulomb center plus a harmonic oscillator. The associated bifurcation diagram is fully explained. Using this information the dynamics of the two particles is described.

Research on Axial Magnetic Field Sensitivity in the Polarization-Maintaining Optical Fiber Coil of Fiber Optic Gyroscope

The magnetic field sensitivity is the main source of errors in a fiber optic gyroscope (FOG) and the polarization-maintaining (PM) optical fiber coil is a major sensitive source. In this paper, a theory that an orthogonal magnetic field vertical to the light propagating direction in a PM optical fiber coil can induce a non-Faraday nonreciprocal phase difference in a FOG is presented. The theoretical simulation and experimental results show that the orthogonal magnetic drift proportional to the orthogonal magnetic field is the main cause of the axial magnetic field sensitivity in a FOG, which is closely related to the skeleton radius of the optical fiber coil and depends neither on the fiber coil's size nor the shape. Furthermore, the orthogonal magnetic field sensitivity will increase with decreasing skeleton radius. Aiming at the application demand of miniaturized gyroscope, the research results of this paper have certain guiding significance and engineering application value.

Экспериментальное исследование поверхностного натяжения ферроколлоида в магнитном поле

Direct measurements of surface tension, viscosity and surface elasticity under the action of external forces are often impossible. In many tasks, the magnetic fluid surface tension is considered to be independent of the magnitude of the applied magnetic field and is determined by the properties of the base fluid. The anisotropy of the magnetic properties at the interface due to the jump in the fluid’s magnetization suggests the dependence of the surface tension tensor on the magnetic field. In this paper, we propose a new experimental method for studying the surface tension of a magnetic fluid in an external uniform magnetic field, depending on the orientation of the magnetic field intensity towards the liquid-gas interface. The study was carried out with the help of modified capillary wave method in a magnetic field orthogonal to the liquid surface and with the ring detachment method in the case of a longitudinal field. It was shown experimentally that the surface tension of a ferrocolloid fluid base (kerosene) does not depend either on the frequency of capillary waves excitation or on intensity of an applied external magnetic field, and corresponds to the value determined with the help of a commercial tensiometer by the standard method of ring detachment. The surface tension of the ferrofluid decreases with increasing intensity of the orthogonal magnetic field interface and with increasing frequency of acoustic vibrations. However, an increase in the field strength longitudinally directed to the interface, provokes an increase in the surface tension of the magnetic fluid. The experimental results are in qualitative agreement with theoretical predictions by A. V. Zhukov: the eigenvalues of the surface tension tensor monotonically increase with the tangential magnetic field component and monotonically decrease with an increase in its normal component.

Development of 1.2-GHz ECR ion source and Wien filter for inexpensive ion beam processing system.

A desktop-sized ion beam processing system with an inexpensive electron cyclotron resonance (ECR) ion source has been developed for industrial applications at the National Institute of Technology, Toyama College. A commercially available 1.2- to 1.3-GHz transceiver is adopted as a microwave source to generate the ECR plasma. The minimum-B magnetic field is formed by arranging small rectangular permanent magnets. A Wien filter with orthogonal electric and magnetic fields is employed as a beam separator. At the end of the beam line, a processing chamber with a substrate stage for ion beam applications, such as ion implantation and microfabrication, is installed. Here, we report the results of the first experiment. Ar ion beams with a current of approximately 62 µA were obtained at an extraction voltage of 4 kV. In addition, we demonstrate that Ar and Xe ions can be separated by the Wien filter.

Source shape impact on controlled source EM surveys

Impact of the shape of grounded-line sources on the frequency domain response observed in the controlled source electromagnetic (CSEM) method has not been addressed thoroughly. In this paper, we use the electromagnetic (EM) fields from a half space as examples to discuss the impact of shape. The EM fields from current dipoles along a curved source are summarized. To illustrate the impact, the ratios of the fields from a curved line source to that of a straight line source with the same current are computed. Numerical results show that the impact of source shape on EM fields occurs mainly from a few hertz to higher frequencies. In our examples, shape deformation causes about 7% variation in the real part, and up to a relative error of ~22.5% in the imaginary part at middle frequencies. However, for the derived impedance, the impact can be ignored. Spatially, in the coaxial zone, the impact of source curvature can also be ignored; but in the equatorial zone near the source, the impact needs to be considered. In our examples, the maximal distance between a curved source and the corresponding straight line source is about 1/4 of the spacing between two current poles, more curved than usually seen in field work. Therefore, our results indicate that we do not need to care about source shape when working in a far zone or with source curvature smaller than that of the sources here. There are two possible ways to lessen the shape impact. One is to lay out grounded line source in a Z shape, but a more complete way is by using impedance derived from orthogonal electrical and magnetic fields to present observed data.

Quantification of Sq parameters in 2008 based on geomagnetic observatory data

The paper presents an investigation of the time-dependent parameters of the solar quiet daily (Sq) variation for the minimum of the solar cycle 23/24 in 2008. We apply “Measure of Anomalousness” algorithm to detection of the magnetically quiet days. Global distribution of Sq amplitudes of the three orthogonal magnetic field components is analyzed using one-year data from 75 INTERMAGNET geomagnetic observatories and 46 SuperMAG stations. The study reveals strong latitudinal dependence of the Sq(X) amplitudes, which is approximated by the sixth-order polynomial trend curve. Sq(Y) amplitudes also suggest latitudinal dependence, while no significant difference is found in the Sq(Z) amplitudes across all latitudes. In the equatorial region, Sq(X) amplitudes are strongly affected by the equatorial electrojet (EEJ), having maxima during equinoctial seasons in the region of the South Atlantic magnetic anomaly (SAA). Sq(Y) demonstrates clear dependence on solar activity and amount of solar illumination, as the Sq(Y) amplitudes are typically greater in the summer-hemisphere and smaller in the winter-hemisphere. We analyze equivalent Sq current system using observatory data from the Australian mainland and narrow European-African latitudinal segment. Sq current system also strongly depends on solar activity, as the current vortices in the winter-hemisphere disintegrate showing no trace of Sq current loops’ formation, while the current vortices become evident in the summer-hemisphere.

Dual-field-induced biaxial nematic ordering of two-dimensional nanoparticles and enhancement of interparticle interactions.

The ordering of 2D biaxial graphene oxide (GO) particles is investigated under the application of orthogonal electric (E) and magnetic fields (B); nematic, antinematic, or biaxial nematic ordering of GO particles is selectively obtained depending on the field conditions. Particularly, a perfect biaxial nematic ordering with the highest birefringence is induced by the dual fields. Unexpectedly, the presence of B enhances the effective polarizability anisotropy, which may attribute to the enhanced steric interparticle interaction. The dual fields induce the microscopic biaxial stacking assembly of GO particles, producing grainy flocs which are not observed in a single-field condition.

On the Asymptotics of the Spectrum of the Hydrogen Atom in Orthogonal Electric and Magnetic Fields Near the Upper Boundaries of Spectral Clusters

The problem of the Zeemann-Stark effect for the hydrogen atom in electromagnetic fields is considered using the irreducible representations of the Karasev-Novikova algebra with quadratic commutation relations. An asymptotics of the series of eigenvalues and the asymptotic eigenfunctions are obtained near the upper boundaries of resonance spectral clusters which are formed near the energy levels of an unperturbed hydrogen atom.

Monte Carlo simulations of out-of-field surface doses due to the electron streaming effect in orthogonal magnetic fields

The out-of-field surface dose contribution due to backscattered or ejected electrons, focused by the magnetic field, is evaluated in this work. This electron streaming effect (ESE) can contribute to out-of-field skin doses in orthogonal magnetic resonance guided radiation therapy machines.Using the EGSnrc Monte Carlo package, a phantom is set-up along the central axis of an incident 10 10 cm2 7 MV FFF photon beam. The phantom exit or entry surface is inclined with respect to the magnetic field, and an out-of-field water panel is positioned 10 cm away from, and centered on, the isocenter. The doses from streaming backscattered or ejected electrons, for either a 0.35 T or 1.5 T magnetic field, are evaluated in the out-of-field water panel for surface inclines of 10, 30, and 45°.The magnetic field focuses electrons emitted from the inclined phantom. Dose distributions at the surface of the out-of-field water panel are sharper in the 1.5 T magnetic field as compared to 0.35 T. The maximum doses for the 0.35 T simulations are 23.2%, 37.8%, and 39.0% for the respective 10, 30, and 45° simulations. For 1.5 T, for the same angles, the maximum values are 17.1%, 29.8%, and 35.8%. Dose values drop to below 2% within the first 1 cm of the out-of-field water phantom. The phantom thickness is an important variable in the magnitude of the ESE dose.The ESE can produce large out-of-field skin doses and must be a consideration in treatment planning in the MRgRT work-flow. Treatments often include multiple beams which will serve to spread out the effect, and many beams, such as anterior–posterior, will reduce the skin dose due to the ESE. A 1 cm thick shielding of either a bolus placed on the patient or mounted on the present RF coils would greatly reduce the ESE dose contributions. Further exploration of the capabilities of treatment planning systems to screen for this effect is required.

Electric field and curvature effects on relativistic Landau levels on a pseudosphere

In this paper relativistic Landau levels on a carbon pseudosphere, whose curvature is a negative constant K = −R−2, are investigated analytically in the presence of orthogonal electric and magnetic fields. It has been shown that the magnetic field tends to create bound states while the electric field tends to destroy them. Consequently there exists a critical electric field such that beyond this critical field the Landau levels collapse although negative curvature of the pseudosphere acts towards preventing the collapse of Landau levels at the critical value.

Thermal transport driven by charge imbalance in graphene in a magnetic field close to the charge neutrality point at low temperature: Nonlocal resistance

Graphene grown epitaxially on SiC, close to the charge neutrality point (CNP), in an orthogonal magnetic field shows an ambipolar behavior of the transverse resistance accompanied by a puzzling longitudinal magnetoresistance. When injecting a transverse current at one end of the Hall bar, a sizeable non local transverse magnetoresistance is measured at low temperature. While Zeeman spin effect seems not to be able to justify these phenomena, some dissipation involving edge states at the boundaries could explain the order of magnitude of the non local transverse magnetoresistance, but not the asymmetry when the orientation of the orthogonal magnetic field is reversed. As a possible contribution to the explanation of the measured non local magnetoresistance which is odd in the magnetic field, we derive a hydrodynamic approach to transport in this system, which involves particle and hole Dirac carriers, in the form of charge and energy currents. We find that thermal diffusion can take place on a large distance scale, thanks to long recombination times, provided a non insulating bulk of the Hall bar is assumed, as recent models seem to suggest in order to explain the appearance of the longitudinal resistance. In presence of the local source, some leakage of carriers from the edges generates an imbalance of carriers of opposite sign, which are separated in space by the magnetic field and diffuse along the Hall bar generating a non local transverse voltage.

Three-dimensional scalar controlled-source audio-frequency magnetotelluric inversion using tipper data

The configuration of the common scalar controlled-source audio-frequency magnetotelluric (CSAMT) method is a solo finite grounded wire and its measuring data are only a set of orthogonal electric and magnetic field data. The receiving electric field for scalar CSAMT is parallel with the grounded wire, which makes the resolution of the direction perpendicular to the grounded wire unsatisfactory, especially for a complex zone. With the increasing demand of complex geological target exploration, the drawback of scalar CSAMT has gradually aroused people's attention. A well-known solution is adopting tensor CSAMT, which is multi-source and measures more data. However, tensor CSAMT needs a much larger workload and is less efficient than scalar CSAMT. This paper researches the tipper data generated from a scalar CSAMT finite grounded wire. Measuring the vertical magnetic field is the only extra workload. The numerical simulation method is a three-dimensional (3D) staggered-grid finite difference. Then we use tipper data with apparent resistivity and phase data to invert two theoretical models. The inversion method is the limited-memory Broyden-Fletcher-Goldfarb-Shanno (LBFGS). Through forward modeling and synthetic data inversion tests, we prove that adopting an apparent resistivity and phase with tipper data can enhance the resolution of scalar CSAMT. Our research shows that using tipper data in scalar CSAMT is useful for electromagnetic exploration.

Explicit Matrix Representation for the Hamiltonian of the One Dimensional Spin 1/2 Ising Model in Mutually Orthogonal External Magnetic Fields

We derive an explicit matrix representation for the Hamiltonian of the Ising model in mutually orthogonal external magnetic fields, using as basis the eigenstates of a system of non-interacting spin 1/2 particles in external magnetic fields. We subsequently apply our results to obtain an analytical expression for the ground state energy per spin, to the fourth order in the exchange integral, for the Ising model in perpendicular external fields.

AC conductivities of a holographic Dirac semimetal

We use the AdS/CFT correspondence to compute the AC conductivities for a (2+1)-dimensional system of massless fundamental fermions coupled to (3+1)-dimensional Super Yang-Mills theory at strong coupling. We consider the system at finite charge density, with a constant electric field along the defect and an orthogonal magnetic field. The holographic model we employ is the well studied D3/probe-D5-brane system. There are two competing phases in this model: a phase with broken chiral symmetry favored when the magnetic field dominates over the charge density and the electric field and a chirally symmetric phase in the opposite regime. The presence of the electric field induces Ohm and Hall currents, which can be straightforwardly computed by means of the Karch-O’Bannon technique. Studying the fluctuations around the stable configurations in linear response theory, we are able to derive the full frequency dependence of longitudinal and Hall conductivities in all the regions of the phase space.

The effect of multidirectional bias magnetic fields on the converse magnetoelectric response of multiferroic concentric composite ring

A composite multiferroic ring was characterized under two orthogonal bias magnetic fields while electrically loaded near resonance to measure the circumferential converse magnetoelectric (CME) response. The composite multiferroic structure consisted of an inner magnetostrictive Terfenol-D ring with an axially aligned preferred magnetocrystalline axis bonded to a radially polarized outer piezoelectric poled lead zirconate titanate ring to form a concentric ring structure. A single uniform bias magnetic field was varied from zero to beyond magnetic saturation while the composite ring's axial alignment was changed from perpendicular to parallel with respect to the bias magnetic field direction. The change in the ring orientation thus subjected the ring to two orthogonal bias magnetic fields, whose strengths were calculated based on the orientation angle. The overall CME behavior was found to be largely correlated with the perpendicular magnetic field strength assisted with the shape anisotropy of the ring structure favoring magnetization along the longest axis. Nonetheless, the parallel magnetic field had a notable contribution to the CME response by enhancing the magnetization in the preferred axial direction and activating other unique magnetocrystalline axes. In all, the CME behavior with respect to two orthogonal bias magnetic fields is characterized by an interplay of magnetocrystalline and shape anisotropies bolstered by the parallel and perpendicular magnetic fields.

Tunneling spectroscopy between one-dimensional helical conductors

We theoretically investigate the tunneling spectroscopy of a system of two parallel one-dimensional helical conductors in the interacting, Luttinger liquid regime. We calculate the nonlinear differential conductance as a function of the voltage bias between the conductors and the orbital momentum shift induced on tunneling electrons by an orthogonal magnetic field. We show that the conductance map exhibits an interference pattern which is characteristic to the interacting helical liquid. This can be contrasted with the different interference pattern from tunneling between regular Luttinger liquids which is governed by the spin-charge separation of the elementary collective excitations.

Nonlinear multimode buckling dynamics examined with semiflexible paramagnetic filaments

We present the contractile buckling dynamics of superparamagnetic filaments using experimental, theoretical, and simulation approaches. Under the influence of an orthogonal magnetic field, flexible magnetic filaments exhibit higher-order buckling dynamics that can be identified as occurring in three stages: initiation, development, and decay. Unlike initiation and decay stages where the balance between magnetic interactions and elastic forces is dominant, in the development stage, the influence of hydrodynamic drag results in transient buckling dynamics that is nonlinear along the filament contour. The inhomogeneous temporal evolution of the buckling wavelength is analyzed and the contractions under various conditions are compared.

Sensitive and stable vector magnetometer for operation in zero and finite fields.

We report on an optically pumped magnetometer that uses multiple laser beams to pump and probe spin-polarized Cs atoms. The selected sensor geometry allows for operation in finite magnetic fields as well as close to zero field. In finite fields the magnetometer employs free spin precession signals to determine the field modulus and direction as described in a separate publication. This publication focuses on the magnetometer operation close to zero field, which is based on a ground state Hanle resonance. The four laser beams permit the simultaneous measurement of two orthogonal magnetic field components in a differential detection scheme that greatly suppresses technical laser power noise. Sensitivities better than 54 fT/Hz1/2 could be demonstrated simultaneously for both measurement channels in a well shielded environment. A minimum Allan deviation, limited by residual field fluctuations, of better than 40 fT was observed for integration times of 2s. The magnetometer achieves high sensitivity and stability in offset fields as well as close to zero field and is, thus, a universal tool for low frequency magnetic field measurements.

Formula omitted] Molecular complex in non-uniform height quantum ribbon under crossed electric and magnetic fields

The D2+ molecular complex fundamental properties in a uniform and multi-hilled semiconductor quantum ribbon under orthogonal electric and magnetic fields are theoretically studied. The energy structure is calculated by using adiabatic approximation combined with diagonalization procedure. The D2+ energy structure is more strongly controlled by the geometrical structural hills than the Coulomb interaction. The formation of vibrational and rotational states is discussed. Aharanov-Bohm oscillation patterns linked to rotational states as well as the D2+ molecular complex stability are highly sensitive to the number of hills while electric field breaks the electron rotational symmetry and removes the energy degeneration between low-lying states.

Analysis of temperature effects in high accuracy ferromagnetic shape memory alloy actuators

The effect of temperature on high accuracy measurements is well known, and temperature controlled environments are a must for metrology of high accuracy mechanical parts. It is therefore not surprising that temperature would play an important role in controlling actuators capable of achieving nanometer resolutions. In most cases the thermal expansion of the components is the main issue with changes with temperature, but in the case of ferromagnetic shape memory alloys (FSMA) based actuators, there are additional complications. First, the material is highly hysteric and when actuated it rapidly self-heats the material. Secondly, the phase transition of the NiMnGa alloy used in the actuator is centered at about 330 K, and at this temperature the performance of the material starts to degrade because it starts to transform into the magnetically inactive cubic phase. In this work we analyze an actuator that uses orthogonal magnetic fields to deform the crystal under no external load. The actuator's control system operates in a “set-and-forget” mode, following an event-based control scheme and is able to achieve a position with a given precision and transient behavior, needing a reduced number of control actions and, then, a reduced energy consumption. In addition, the paper discusses the control implications of the temperature dependency of the actuator's behavior, based on experimental results.