Uniform Static Magnetic Field Research Articles

On the electromagnetic interaction and the anomalous term in the Duffin-Kemmer-Petiau theory

The problem of vectorial mesons embedded in an electromagnetic field via Duffin-Kemmer-Petiau (DKP) formalism is reinvestigated. Considering the electromagnetic interaction as a minimal coupling, an incorrect value is identified for the gyromagnetic factor (g-factor). Furthermore, it is shown that it is cumbersome to find analytical solutions due to the presence of the so-called anomalous term for the spin-1 sector of the DKP theory. Suspecting that the anomalous term results from an incomplete version of the DKP equation to describe the electromagnetic interaction, we consider the addition of a non-minimal coupling. This leads to the correct g-factor and, as a consequence, the anomalous term becomes proportional to an external four current. As an application, the DKP equation with a static uniform magnetic field is considered, yielding the corresponding Landau levels.

Surface wave propagation along a narrow transition layer in a slab Voigt geometry

The dispersion properties of electromagnetic surface waves, which propagate along a slab narrow transition layer separating two magnetoactive plasma uniform half spaces, are studied. Voigt geometry is considered, in which the waves propagate perpendicularly to an external uniform static magnetic field, which in turn is parallel to the interfaces between the plasmas and the transition layer. Electromagnetic power absorption within local resonances inside the transition layer is out of scope of the study. The influence of the plasma particle density profile smoothness on the surface wave dispersion properties is emphasized.

Electromagnetohydrodynamic (EMHD) convective transport of a reactive dissipative carreau fluid with thermal ignition in a non-Darcian vertical duct

A mathematical model is developed to simulate the steady, laminar exothermic reactive electromagneto-hydrodynamic combustible non-Newtonian natural convective transport in a vertical duct. Static uniform axial electrical field and transverse magnetic field are imposed. The Frank-Kamenetskii thermal explosion theory is utilized and also the Carreau fluid model, the latter due to its ability to simulate shear-thinning, Newtonian and shear-thickening behaviour. The duct contains a homogenous, isotropic porous medium and to accomodate Forchheimer inertial drag effects, a non-Darcian model is deployed. The duct walls are permeable enabling suction and injection effects to be studied. Viscous and Joule heating (Ohmic dissipation) are also featured in the model. Following a scaling transformation, the dimensionless emerging non-linear ordinary differential boundary value problem is solved with a robust numerical method (Mathematica shooting algorithm). Validation with an Adomian decomposition method (ADM) is included.

Excitation of an upper hybrid wave by Laguerre–Gaussian pulse in plasma with a density ramp and electron acceleration

In this paper, the excitation of an upper hybrid wave (UHW) by propagation of a Laguerre–Gaussian (LG) laser pulse in an exponential density ramp plasma has been investigated in relativistic regime. A uniform static magnetic field was externally applied perpendicular to the propagation of the laser. The spatiotemporal dynamics of laser pulse have been studied by two coupled differential equations obtained via the moment theory approach. The propagating laser pulse excites an electron plasma wave, which further interacts with the laser pulse in the presence of applied transverse magnetic field and generates an UHW. The excited UHW further traps the plasma electrons and accelerates them. It has been observed that the presence of density ramp affects the laser dynamics, excited UHW, and electron acceleration. The applied magnetic field and modes of LG laser have also shown significant effect on electron acceleration. Energy gain of the order of 400 MeV/mm has been obtained for electrons.

Mean flow and Convective instability analysis of the BEK and related rotating boundary layer flows subject to a uniform static magnetic field

This study examines the convective instability of the hydromagnetic Bödewadt, Ekman, and von Kármán (BEK) rotating system under the low magnetic Reynolds number approximation. The computations for the mean flow are carried out for different magnetic parameters using MATLAB for several flows of the BEK family. The equations for the linear instability are derived and then solved through the Chebyshev-spectral method for both Type-I (Inviscid) and Type-II (viscous) modes. It is observed that the Rossby number, the Reynolds number, and the magnetic parameter characterize the stability of the hydromagnetic BEK flows. The Reynolds number is based on the dimensionless radial location at the disk while the Rossby number is the ratio of the difference between the angular speeds of fluid and disk and the angular speed of the disk. The magnetic number is the ratio of magnetic field strength and the system rotation rate. The analysis reveals a stabilizing effect of the magnetic parameter on the Type-I modes for Rossby numbers in the range [−1,1]. Further, the Type-II modes disappear upon elevating the magnetic parameter in the aforementioned range of the Rossby number. The growth rates, |αi|, also diminish upon increasing the magnetic parameter. The computations for mean flow reveal that the radial wall shear stress diminishes upon elevating the strength of the applied magnetic field. However, a reverse trend is noted for the azimuthal wall shear stress which indicates an increase in the torque on the disk with enhancing the intensity of the magnetic field.

Charged pseudoscalar and vector meson masses in strong magnetic fields in an extended NJL model

The mass spectrum of ${\ensuremath{\pi}}^{+}$ and ${\ensuremath{\rho}}^{+}$ mesons in the presence of a static uniform magnetic field $\stackrel{\ensuremath{\rightarrow}}{B}$ is studied within a two-flavor Nambu-Jona-Lasinio-like model. We improve previous calculations, taking into account the effect of Schwinger phases carried by quark propagators and using an expansion of meson fields in terms of the solutions of the corresponding equations of motion for nonzero $B$. It is shown that the meson polarization functions are diagonal in this basis. Our numerical results for the ${\ensuremath{\rho}}^{+}$ meson spectrum are found to disfavor the existence of a meson condensate induced by the magnetic field. In the case of the ${\ensuremath{\pi}}^{+}$ meson, $\ensuremath{\pi}$---$\ensuremath{\rho}$ mixing effects are analyzed for the meson lowest-energy state. The predictions of the model are compared with available lattice QCD results.

Dust–ion acoustic solitary waves in a collisionless magnetized five components plasma

Abstract We have derived a Korteweg–de Vries–Zakharov–Kuznetsov (KdV-ZK) equation to study the nonlinear behavior of dust–ion acoustic waves in a collisionless magnetized five components dusty plasma consisting of warm adiabatic ions, nonthermal hot electrons, isothermal cold electrons, nonthermal positrons and static negatively charged dust particulates. It is found that the coefficient of the nonlinear term of the KdV-ZK equation vanishes along different family of curves in different compositional parameter planes. In this situation, to describe the nonlinear behavior of dust–ion acoustic waves, we have derived a modified KdV-ZK (MKdV-ZK) equation. When the coefficients of the nonlinear terms of both KdV-ZK and MKdV-ZK equations are simultaneously equal to zero, then we have derived a further modified KdV-ZK (FMKdV-ZK) equation which effectively describes the nonlinear behavior of dust–ion acoustic waves. Analytically and numerically, we have investigated the solitary wave solutions of different evolution equations propagating obliquely to the direction of the external static uniform magnetic field. We have seen that the amplitude of the KdV soliton strictly increases with increasing β e, whereas the amplitude of the MKdV soliton strictly decreases with increasing β e, where β e is the nonthermal parameter associated with the hot electron species. Also, there exists a critical value β r ( c ) ${\beta }_{\text{r}}^{(\text{c})}$ of β e such that the FMKdV soliton exists within the interval β r ( c ) < β e ≤ 4 7 ${\beta }_{\text{r}}^{(\text{c})}< {\beta }_{\text{e}}\le \frac{4}{7}$ , whereas the FMKdV soliton does not exist within the interval 0 < β e < β r ( c ) $0< {\beta }_{\text{e}}< {\beta }_{\text{r}}^{(\text{c})}$ . We have also discussed the effect of different parameters of the system on solitary waves obtained from the different evolution equations.

A Monte Carlo study on the effects of a static uniform magnetic field on micro-scale dosimetry of Auger-emitters using Geant4-DNA

In this work, an effort has been made to improve cellular dosimetry of Auger radionuclides through investigating any possible effect of an applied static uniform magnetic field (up to 10 T) on the absorbed doses of ionizing radiation in the micron-sized spherical volumes of liquid water per unit cumulated activity (S-values). The Geant4-DNA extension of the Geant4 Monte Carlo toolkit was employed to simulate the radioactive decay of several theranostic Auger-emitters, including 99mTc, 111In, 123I, 125I, and 201Tl which, distributed within various compartments of a typical spherical cell model. The S-values were calculated in the target regions belonging to both the cell containing the electron source (self-dose) and the second similar cell adjacent to it (cross-dose), with and without the presence of the magnetic field. The results related to the self- and cross-dose cases in the zero magnetic fields were compared to the corresponding MIRD ones. Based on the obtained results for the examined radionuclides and cell dimensions, it can be concluded that the self-dose values are not affected by a static uniform magnetic field, but the cross-dose ones increase slightly (up to 19%) depending on the orientation and strength of the magnetic field.

Drift of suspended single-domain nanoparticles in a harmonically oscillating gradient magnetic field

We study the nonlinear dynamics of single-domain ferromagnetic nanoparticles in a viscous liquid induced by a harmonically oscillating gradient magnetic field in the absence and presence of a static uniform magnetic field. Under some physically reasonable assumptions, we derive a coupled set of stiff ordinary differential equations for the magnetization angle and particle coordinate describing the rotational and translational motions of nanoparticles. Analytical solutions of these equations are determined for nanoparticles near and far from the coordinate origin, and their correctness is confirmed numerically. We show that if a uniform magnetic field is absent, the magnetization angle and particle coordinate of each nanoparticle are periodic functions of time. In contrast, the presence of a uniform magnetic field makes these functions aperiodic. In this case, we perform a detailed analysis of the nanoparticle dynamics and predict the appearance of the drift motion (directed transport) of nanoparticles. We calculate both analytically and numerically the drift velocity, study its dependence on time and model parameters, analyze the physical origin of the drift phenomenon and discuss its potential biomedical applications.

Biomimetic Chaotic Sensor for Moderate Static Magnetic Field.

The effects of a static magnetic field on systems with chaotic dynamical behavior have attracted little attention so far. Here, Chua’s electronic circuit with an inductor placed in a static uniform magnetic field operating in a chaotic double-scroll regime is studied experimentally. The effect of the magnetic field on the duty cycle factor and the spike count rate, with spikes defined by crossings between the scrolls of the double-scroll attractor, is described. A slow monotonic variation in the duty cycle factor and constant spike count rate is observed for magnetic field intensities up to the threshold, where both these metrics change severely; the dynamic trajectory remains on one scroll and spikes disappear. The dependence of the static magnetic field intensity on Chua’s circuit resistivity at the threshold is given. Two biomimetic magnetic chaotic sensors are proposed: one based on one Chua’s circuit and another that can have various transfer functions and is composed of several independent Chua’s circuits.

Helicon wave plasma generated by a resonant birdcage antenna: magnetic field measurements and analysis in the RAID linear device

This paper describes a helicon-wave-sustained plasma generated by a novel birdcage antenna with cosine azimuthal current distribution. The resonant birdcage source maintains a stable intense plasma column from low (300 W) to high (10 kW) steady-state RF power in hydrogen or argon, enabling plasma diagnostic measurements over the whole volume. The plasma density, 1018 to 1019 m−3, and uniform static magnetic field, 200–800 G, are typical of high density, low B-field helicon sources where the RF excitation frequency, 13.56 MHz here, is far above the ion cyclotron frequency and much lower than the electron cyclotron and plasma frequencies. Magnetic field measurements of the unbounded plasma column show a helicon wave propagating from the birdcage source to the target 1.5 m away. The axial wavelength, measured for a range of plasma density and magnetic field, is described by the whistler dispersion relation; it is not determined by the antenna length but varies smoothly as a function of electron density irrespective of the gas type, and shows no discontinuous transitions. This wavelength was compared with semi-analytical and purely numerical models, showing a good fit with the m = +1 helicon eigenvalue of shortest axial wavelength. The birdcage resonant antenna is a suitable source for continuous helicon-sustained plasma experiments, from fundamental wave studies up to high power applications in hydrogen or deuterium.

Betaboltz: A Monte-Carlo simulation tool for gas scattering processes

We present an open-source code for the simulation of electron and ion transport for user-defined gas mixtures with static uniform electric and magnetic fields. The program provides microscopic interaction simulation and is interfaced with cross-section tables published by LXCat[1]. The framework was validated against drift velocity tables available in literature obtaining an acceptable match for atomic and non-polar molecular gases with spherical symmetry. The code is written in C++17 and is available as a shared library for easy integration into other simulation applications. Program summaryProgram Title: BetaboltzCPC Library link to program files:https://doi.org/10.17632/hjhx8bj45c.1Licensing provisions: LGPL v3Programming language: C++17Nature of problem: Simulations of electron and ion transport in arbitrary gas mixture under static uniform electric and magnetic fields.Solution method: Particle motion using classical and relativistic equation via interaction sampling using Monte-Carlo techniques.Additional comments including restrictions and unusual features: At the time of writing only static uniform electromagnetic fields are supported. However, the implementation of arbitrary fields can be added given an analytical solution is available. A custom XML format for cross-section was developed, because full compatibility with LXCat [1] XML format was not possible. Cross-section databases in the new format are available in the download section of the LXCat site [2].

Arbitrary amplitude ion acoustic solitons, double layers and supersolitons in a collisionless magnetized plasma consisting of non-thermal and isothermal electrons

Abstract Using Sagdeev pseudo-potential technique, we have studied the arbitrary amplitude ion acoustic solitons, double layers and supersolitons in a collisionless plasma consisting of adiabatic warm ions, non-thermal hot electrons and isothermal cold electrons immersed in an external uniform static magnetic field. We have used the phase portraits of the dynamical system describing the non-linear behaviour of ion acoustic waves to confirm the existence of different solitary structures. We have found that the system supports (a) positive potential solitons, (b) negative potential solitons, (c) coexistence of both positive and negative potential solitons, (d) negative potential double layers, (e) negative potential supersolitons and (f) positive potential supersolitons. Again, we have seen that the amplitude of the positive potential solitons decreases or increases with increasing n ch according to whether 0 < n c h < n c h ( c ) $0{< }{n}_{ch}{< }{n}_{ch}^{\left(c\right)}$ or n c h ( c ) < n c h ≤ 1 ${n}_{ch}^{\left(c\right)}{< }{n}_{ch}\le 1$ , where n c h ${n}_{ch}$ is the ratio of isothermal cold and non-thermal hot electron number densities, and n c h ( c ) ${n}_{ch}^{\left(c\right)}$ is a critical value of n ch . Also, we have seen that the amplitude of the positive potential solitons decreases with increasing β e , where β e is the non-thermal parameter. We have also investigated the transition of different negative potential solitary structures: negative potential soliton (before the formation of negative potential double layer) → negative potential double layer → negative potential supersoliton → negative potential soliton (after the formation of negative potential double layer) by considering the variation of θ only, where θ is angle between the direction of the external uniform static magnetic field and the direction of propagation of the ion acoustic wave.

Between no slip and free slip: A new boundary condition for the surface hydrodynamics of a molten metal

As an attempt to take into account the mechanical role of oxide films at the liquid surface of melted or liquid metal flows, a model is proposed based on a Boussinesq-Scriven law corrected by a non-Newtonian behavior. A characterisation device is developed based on an annular open-channel viscometer positioned in a chemical reactor and pervaded by a uniform static magnetic field. The chemical reactor makes it possible to monitor the oxidation process at the liquid-gas interface. The uniform vertical magnetic field allows to monitor the surface shear at the oxide layer thanks to the 2D tendency of low Rm MHD. Both the highly viscous nature and the shear-thinning behavior of the oxide layer are made evident, as confirmed by numerical simulations and scanning electron microscopy. These results are believed to be insightful to calculation of flows in metallurgy industry (casting flows, 3-D printing or additive manufacturing of metals for instance).

Quantitative Analysis of the Specific Absorption Rate Dependence on the Magnetic Field Strength in ZnxFe3-xO4 Nanoparticles.

Superparamagnetic ZnxFe3−xO4 magnetic nanoparticles (0 ≤ x < 0.5) with spherical shapes of 16 nm average diameter and different zinc doping level have been successfully synthesized by co-precipitation method. The homogeneous zinc substitution of iron cations into the magnetite crystalline structure has led to an increase in the saturation magnetization of nanoparticles up to 120 Am2/kg for x ~ 0.3. The specific absorption rate (SAR) values increased considerably when x is varied between 0 and 0.3 and then decreased for x ~ 0.5. The SAR values are reduced upon the immobilization of the nanoparticles in a solid matrix being significantly increased by a pre-alignment step in a uniform static magnetic field before immobilization. The SAR values displayed a quadratic dependence on the alternating magnetic field amplitude (H) up to 35 kA/m. Above this value, a clear saturation effect of SAR was observed that was successfully described qualitatively and quantitatively by considering the non-linear field’s effects and the magnetic field dependence of both Brown and Neel relaxation times. The Neel relaxation time depends more steeply on H as compared with the Brown relaxation time, and the magnetization relaxation might be dominated by the Neel mechanism, even for nanoparticles with large diameter.

Thermodynamically Consistent Analysis of Magnetocaloric Effects

We suggest a thermodynamically and mathematically consistent analysis of magnetocaloric effect for a plate immersed in a uniform static magnetic field. We ignore deformability of the plate, but make no assumption regarding the amplitude of the magnetic field - it can be arbitrarily large. Traditional presentations of magnetocaloric effect are rather simple and straightforward - they are based on the algebraic manipulations with thermodynamic identities, and no analysis of boundary value problems is required. But they suffer one conceptual drawback - they are dealing with the magnetic field inside the specimen. However, the interior field is, a priori, unknown and depends on the geometry of the specimen. In fact, the meaningful analysis should be based on usage of the experimentally controllable exterior field. The relevant analysis therefore, should be based on the consideration of the boundary value problem for the equations of magnetostatics. We establish the relevant relationships of the magnetocaloric effect for the sample in the shape of a plate.

Giant Goos–Hänchen shift of a reflected spin wave from the ultrathin interface separating two antiferromagnetically coupled ferromagnets

The Goos–Hänchen (GH) shift of a spin wave (SW) reflected from the ultrathin nonmagnetic interface between two antiferromagnetically coupled ferromagnetic materials is theoretically investigated. The analytical formulas of the reflection coefficient and the GH shift are derived. The GH shift as a function of the incident angle, the frequency, the external magnetic field, and the uniform exchange parameter is studied. We show that the uniform static external magnetic field and the uniform exchange parameter have a significant impact on the GH shift. Moreover, a giant negative GH shift, which reaches value three orders of magnitude larger than the wavelength of the SW, is observed. Our results will be applied in magnonics, and provide one who studies the GH shift of the SW theoretically or experimentally with some useful help.

Moderate Range Static Magnetic Field Promoted Variation of Blood Parameters: An In vitro Study

This study was undertaken to investigate the influence of a homogenous and uniform static magnetic field (SMF) on the main blood cell counts in vitro experiment. Fresh blood samples were collected from albino rats and exposed to SMF (2.4, 6, 25, 50, 75, and 100 mT) versus 15–60 min. Results showed a significant change of blood counts under the low field effects. A 2.4 mT was a trend of white blood cells (WBCs) count increase non-linearly. However, a 6 mT exposure reduced WBCs with about 39%. Other variations fluctuated within 30%. The 25 mT decreased red blood cells (RBCs), hemoglobin, and hematocrit levels with 13% similarly. The lower exposure field, (2.4 and 6) mT, and effects on RBCs were 6% fluctuation. The 6 mT reduced platelet counts with half in comparison to control blood samples. About 20% increase obtained due to 50 mT exposure during all period. None of 75 and 100 mT exposures dominated blood counts alterations. The quiet magnetic field exposure for a certain time can be interesting to control blood cell count-related diseases.

Energy gain by laser-accelerated electrons in a strong magnetic field.

This paper deals with electron acceleration by a laser pulse in a plasma with a static uniform magnetic field B_{*}. The laser pulse propagates perpendicular to the magnetic field lines with the polarization chosen such that (E_{laser}·B_{*})=0. The focus of the work is on the electrons with an appreciable initial transverse momentum that are unable to gain significant energy from the laser in the absence of the magnetic field due to strong dephasing. It is shown that the magnetic field can initiate an energy increase by rotating such an electron, so that its momentum becomes directed forward. The energy gain continues well beyond this turning point where the dephasing drops to a very small value. In contrast to the case of purely vacuum acceleration, the electron experiences a rapid energy increases with the analytically derived maximum energy gain dependent on the strength of the magnetic field and the phase velocity of the wave. The energy enhancement by the magnetic field can be useful at high laser amplitudes, a_{0}≫1, where the acceleration similar to that in the vacuum is unable to produce energetic electrons over just tens of microns. A strong magnetic field helps leverage an increase in a_{0} without a significant increase in the interaction length.

Effect of Landau damping on ion acoustic solitary waves in a collisionless unmagnetized plasma consisting of nonthermal and isothermal electrons

We have used the Sagdeev pseudo-potential technique to investigate the arbitrary amplitude ion acoustic solitons, double layers and supersolitons in a collisionless magnetized plasma consisting of adiabatic warm ions, isothermal cold electrons and nonthermal hot electrons immersed in an external uniform static magnetic field. We have used the phase portraits of the dynamical system describing the nonlinear behaviour of ion acoustic waves to confirm the existence of different solitary structures. We have also investigated the transition of different solitary structures: soliton (before the formation of double layer) $\rightarrow$ double layer $\rightarrow$ supersoliton $\rightarrow$ soliton (soliton after the formation of double layer) by considering the variation of $\theta$ only, where $\theta$ is the angle between the direction of the external uniform static magnetic field and the direction of propagation of the wave.