Shape Of Magnetic Field Research Articles

Effect of the magnetic field strength on the argon plasma characteristics of a helicon plasma source with a two-turn flat-loop antenna

New plasma applications in advanced fields, such as fundamental nuclear fusion research, require high-density, large-diameter plasma with a strong and non-uniform magnetic field. A helicon plasma (HP) source using a flat-type antenna is expected to be one of the promising methods for such applications. In this study, we developed an HP source with a two-turn flat-loop antenna connected to a 30 kW radio frequency power supply in the Compact Test Plasma device. In the argon plasma generation experiment with various magnetic fields, HP generation was observed for the first time in this device. The electron density was calculated from the dispersion relation with the magnetic field strength at 45 cm from the antenna surface, assuming a fundamental radial mode and an azimuthal mode of $m=0$ . The electron density expected from the experimental result was approximately in the same range as the calculation result by a factor of 2.3 to 3.5. In addition, the magnetic field strength and shape around the antenna are important factors in the plasma properties. This plasma source has been installed in the pilot GAMMA PDX-SC, which is under development for nuclear plasma research, and it contributes to the study of the HP generation process.

Bjet_MCMC: A New Tool to Automatically Fit the Broadband Spectral Energy Distributions of Blazars

Multiwavelength observations are now the norm for studying blazars’ various states of activity, classifying them, and determining the possible underlying physical processes driving their emission. Broadband emission models became unavoidable tools for testing emission scenarios and setting the values of physical quantities such as the magnetic field strength, Doppler factor, or shape of the particle distribution of the emission zone(s). We announce here the first public release of a new tool, Bjet_MCMC, that can automatically fit the broadband spectral energy distributions (SEDs) of blazars. The complete code is available on GitHub and allows for testing leptonic synchrotron self-Compton models with or without external inverse-Compton processes from the thermal environment of supermassive black holes (accretion disk and broad-line region). The code is designed to be user-friendly and computationally efficient. It contains a core written in C++ and a fully parallelized SED fitting method. The original multi-SSC zone model of Bjet is also available on GitHub but is not included in the Markov Chain Monte Carlo fitting process at the moment. We present the features, performance, and results of Bjet_MCMC, as well as user advice.

Spontaneous Vortex-Antivortex Pairs and Their Topological Transitions in a Chiral-Lattice Magnet.

The spontaneous formation and topological transitions of vortex-antivortex pairs have implications for a broad range of emergent phenomena, for example, from superconductivity to quantum computing. Unlike magnets exhibiting collinear spin textures, helimagnets with noncollinear spin textures provide unique opportunities to manipulate topological forms such as (anti)merons and (anti)skyrmions. However, it is challenging to achieve multiple topological states and their interconversion in a single helimagnet due to the topological protection for each state. Here, the on-demand creation of multiple topological states in a helimagnet Fe0.5 Co0.5 Ge, including a spontaneous vortex pair of meron with topological charge N=-1/2 and antimeron with N=1/2, and a vortex-antivortex bundle, that is, a bimeron (meron pair) with N=-1 is reported. The mutual transformation between skyrmions and bimerons with respect to the competitive effects of magnetic field and magnetic shape anisotropy is demonstrated. It is shown that electric currents drive the individual bimerons to form their connecting assembly and then into a skyrmion lattice. These findings signify the feasibility of designing topological states and offer new insights into the manipulation of noncollinear spin textures for potential applications in various fields.

Study on the Influence of Synthesized Nano Ferrite Powder and Micron Ferrite Powder on Damping of a Single Degree of Freedom System

Magneto Rheological Fluid (MRF) damper has been opted as a promising semi active element of advanced suspension system. This work focuses on the damping nature of magnetorheological fluid under the influence of a magnetic field strength, size and shape of the of the iron oxide particles. A reduced scale single degree of freedom quarter car model with two stage magnetorheological damper, viscosity measurement setup, synthesized and commercially available Fe2O3 powders are used for the experimental study. An air cooled electro-dynamic shaker, Data acquisition system, accelerometers and the Lab view software acquires and analyzes the response of the quarter car model. X-ray Diffraction and Scanning electron microscopy characterize the morphology of iron oxide particles. The vertical acceleration, the displacement, the transmissibility ratio and the damping characteristics are analyzed based on the response of the top plate at different frequencies of base excitation. The results show that the magnetorheological fluid made with nano iron oxide powder has better damping characteristics than that of micron sized iron oxide powder

Spin dynamics of exchange-coupled nitrogen donors in heavily dopedn-type15RSiC monocrystals: Multifrequency EPR and EDMR study

Semiconductor devices based on $15R$ silicon carbide (SiC) show improved properties compared to other polytypes. Here, we report the investigation of nitrogen-doped $15R$ SiC monocrystals with $({N}_{\mathrm{D}}--{N}_{\mathrm{A}})\ensuremath{\sim}5\ifmmode\times\else\texttimes\fi{}{10}^{18}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}3}$ using multifrequency electron paramagnetic resonance (EPR) and electrically detected magnetic resonance (EDMR) spectroscopic methods in the microwave (MW) frequency range from 9.4 to 328.84 GHz and in the temperature range from 4.2 to 300 K. A single intensive $S$ line with $S=1/2$, at ${g}_{\ensuremath{\perp}}=2.0026(2)$, and ${g}_{\ensuremath{\parallel}}=2.0043(2)$ dominates the EPR spectrum in $15R$ SiC at $T<160$ K and was attributed to the exchange-coupled nitrogen (N) donors substituting quasicubic ``$k1$'' site having the deeper energy level in $15R$ SiC lattice. From the analysis of the temperature behavior of the integral intensity, magnetic field position, intensity, shape, and width of the $S$ line, it was concluded that at $T<90$ K, the exchange coupling occurs between localized donor electrons, while at $T=90\ensuremath{-}150$ K the interaction between exchange-coupled N donors and conduction electrons takes place. In the temperature interval from 20 to 160 K, the $S$-line EPR width was characterized by a two-phonon Orbach relaxation process with the activation energy of $\ensuremath{\sim}6.5$ meV corresponding to the valley-orbit splitting values for N donors in $15R$ SiC. The variable-range hopping regime obeying the ${T}^{1/4}$ law was found to take place at $T<20$ K leading to the appearance of the $S$ line in the EDMR spectrum at low temperatures. The appearance of the EDMR signal from exchange-coupled N donors is caused by the EPR-induced temperature-increase mechanism and the spin-flip hops process. The results obtained from MW conductivity measurements agree with EPR and EDMR data. The temperature variation of MW conductivity was described by several processes, including the electron-hopping process between N donor impurity atoms at $T<50$ K with activation energy ${\ensuremath{\varepsilon}}_{3}=1.5$ meV, electron transitions between Hubbard bands at $T=50--100$ K; the transition of the electrons from the donor energy levels to conduction band with ionization energy ${\ensuremath{\varepsilon}}_{1}=32$ meV at $T=100--200$ K and scattering of the conduction electrons by ionized donors occurred at the temperature higher than 200 K.

Exciton regulation mechanism of Alq<sub>3</sub>/HAT-CN tandem electroluminescent devices

Tandem organic electroluminescent devices (OLEDs) have attracted widespread attention due to their long lifetime and high current efficiency. In this study, a double-emitting unit tandem OLED is fabricated by using Alq<sub>3</sub>/HAT-CN as an interconnect layer. Its photovoltaic properties and exciton regulation mechanism are investigated. The results show that the luminance (11189.86 cd/m<sup>2</sup>) and efficiency (13.85 cd/A) of the tandem OLED reaches 2.7 times that of the single electroluminescent (EL) unit OLED (luminance and efficiency of 4007.14 cd/m<sup>2</sup> and 5.00 cd/A, respectively) at a current density of 80 mA/cm<sup>2</sup>. This proves that the Alq<sub>3</sub>/HAT-CN is an efficient interconnect layer. At room temperature, the polaron pair undergoes intersystem crossing (ISC) due to hyperfine interaction (HFI) when a magnetic field is applied to the device. This increases the concentration of the triplet excitons (T<sub>1</sub>), thus promoting the charge scattering. The result is a rapid increase in the low magnetic field and a slow increase in the high magnetic field of the MEL. When the injection current strength is constant, there is less uncompounded charge in the Alq<sub>3</sub>/HAT-CN device than in other connected layer devices. Triplet-charge annihilation (TQA) is weak, resulting in a relative increase in the value of T<sub>1</sub>, which is not involved in the TQA. This suppresses the ISC and leads to a minimal increase in the MEL. As the current strength increases, the T<sub>1</sub> value increases, causing TQA to increase and ISC to decrease. Since the TQA is related to charge and T<sub>1</sub> value, lowering the temperature reduces the carrier mobility in the device, resulting in the relative decreasing of charge concentration and the weakening of TQA. Lowering the temperature reduces the quenching of thermal phonons and increases the T<sub>1</sub> value while extending its lifetime, resulting in the enhancement of triplet-triplet annihilation (TTA). At low temperatures, the high magnetic field shape of the MEL changes from slowly increasing to rapidly decreasing. Therefore, the T<sub>1</sub> value can be regulated by varying the current strength and temperature, which further affects the strength of ISC, TQA and TTA, and the luminescence and efficiency of the device can be effectively improved by reducing TQA and ISC. This work is of great significance in understanding the luminescence mechanism of small molecule tandem devices and studying the mechanism for improving their photovoltaic properties.

The effect of magnetic field parameters on fibre orientation in high-performance fibre-reinforced concrete

We aim at determining the value of minimal magnetic induction for magnetic orientation of fibres in cementitious composite in a given mixture and establish the effect of the magnetic field shape on the final mechanical properties. The magnetic orientation is a suitable method to ensure the required direction of steel ferromagnetic fibres in the composite. The strength of the magnetic field (magnetic induction) and rheology of the fresh mixture play a crucial role in the magnetic orientation. A special device generating alternating and direct magnetic fields with different magnetic inductions was built to determine the minimal magnetic induction for the given mixture. Moreover, the effects of using alternating magnetic field are explored. The used magnetic inductions are 60 mT, 80 mT, 100 mT and 120 mT. The nondestructive inductive measuring method is applied to confirm the orientation of fibres in the hardened composite. The effect of the shape of the magnetic field and magnetic induction on flexural strength is presented. Moreover, the effects of using the alternating or direct magnetic field on the microstructure are explored using a scanning electron microscope.

Permanent-Magnet Optimization for Stellarators as Sparse Regression

A common scientific inverse problem is the placement of magnets that produce a desired magnetic field inside a prescribed volume. This is a key component of stellarator design, and recently permanent magnets have been proposed as a potentially useful tool for magnetic field shaping. Here, we take a closer look at possible objective functions for permanent magnet optimization, reformulate the problem as sparse regression, and propose an algorithm that can efficiently solve many convex and nonconvex variants. The algorithm generates sparse solutions that are independent of the initial guess, explicitly enforces maximum strengths for the permanent magnets, and accurately produces the desired magnetic field. The algorithm is flexible, and our implementation is open-source and computationally fast. We conclude with two new permanent magnet configurations for the NCSX and MUSE stellarators. Our methodology can be additionally applied for effectively solving permanent magnet optimizations in other scientific fields, as well as for solving quite general high-dimensional, constrained, sparse regression problems, even if a binary solution is required.

Neutral Beam Coupling with Plasma in a Compact Fusion Neutron Source

FNS-ST is a fusion neutron source project based on a spherical tokamak (R/a = 0.5 m/0.3 m) with a steady-state neutron generation of ~1018 n/s. Neutral beam injection (NBI) is supposed to maintain steady-state operation, non-inductive current drive and neutron production in FNS-ST plasma. In a low aspect ratio device, the toroidal magnetic field shape is not optimal for fast ions confinement in plasma, and the toroidal effects are more pronounced compared to the conventional tokamak design (with R/a > 2.5). The neutral beam production and the tokamak plasma response to NBI were efficiently modeled by a specialized beam-plasma software package BTR-BTOR, which allowed fast optimization of the neutral beam transport and evolution within the injector unit, as well as the parametric study of NBI induced effects in plasma. The “Lite neutral beam model” (LNB) implements a statistical beam description in 6-dimensional phase space (106–1010 particles), and the beam particle conversions are organized as a data flow pipeline. This parametric study of FNS-ST tokamak is focused on the beam-plasma coupling issue. The main result of the study is a method to achieve steady-state current drive and fusion controllability in beam-driven toroidal plasmas. LNB methods can be also applied to NBI design for conventional tokamaks.

Shaping and Focusing Magnetic Field in the Human Body: State-of-the Art and Promising Technologies.

In recent years, the usage of radio frequency magnetic fields for biomedical applications has increased exponentially. Several diagnostic and therapeutic methodologies exploit this physical entity such as, for instance, magnetic resonance imaging, hyperthermia with magnetic nanoparticles and transcranial magnetic stimulation. Within this framework, the magnetic field focusing and shaping, at different depths inside the tissue, emerges as one of the most important challenges from a technological point of view, since it is highly desirable for improving the effectiveness of clinical methodologies. In this review paper, we will first report some of the biomedical practices employing radio frequency magnetic fields, that appear most promising in clinical settings, explaining the underneath physical principles and operative procedures. Specifically, we direct the interest toward hyperthermia with magnetic nanoparticles and transcranial magnetic stimulation, together with a brief mention of magnetic resonance imaging. Additionally, we deeply review the technological solutions that have appeared so far in the literature to shape and control the radio frequency magnetic field distribution within biological tissues, highlighting human applications. In particular, volume and surface coils, together with the recent raise of metamaterials and metasurfaces will be reported. The present review manuscript can be useful to fill the actual gap in the literature and to serve as a guide for the physicians and engineers working in these fields.

Experimental Investigation on the Effect of Surface Shape and Orientation in Magnetic Field Assisted Mass Polishing.

Magnetic field assisted finishing (MFAF) technology has been widely used in industries such as aerospace, biomedical, and the optical field for both external and internal surface finishing due to its high conformability to complex surfaces and nanometric surface finishing. However, most of the MFAF methods only allow polishing piece-by-piece, leading to high post-processing costs and long processing times with the increasing demand for high precision products. Hence, a magnetic field-assisted mass polishing (MAMP) method was recently proposed, and an experimental investigation on the effect of surface posture is presented in this paper. Two groups of experiments were conducted with different workpiece shapes, including the square bar and roller bar, to examine the effect of surface orientation and polishing performance on different regions. A simulation of magnetic field distribution and computational fluid dynamics was also performed to support the results. Experimental results show that areas near the chamber wall experience better polishing performance, and the surface parallel or inclined to polishing direction generally allows better shearing and thus higher polishing efficiency. Both types of workpieces show notable polishing performance where an 80% surface roughness improvement was achieved after 20-min of rough polishing and 20-min of fine polishing reaching approximately 20 nm.

Phonon-induced rotation of the electronic nematic director in superconducting Bi2Se3

The doped topological insulator ${A}_{x}{\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$, with $A={\mathrm{Cu},\mathrm{Sr},\mathrm{Nb}}$, becomes a nematic superconductor below ${T}_{c}\ensuremath{\approx}3$--4 K. The associated electronic nematic director is described by an angle $\ensuremath{\alpha}$ and is experimentally manifested in the elliptical shape of the in-plane critical magnetic field ${H}_{c2}$. Because of the threefold rotational symmetry of the lattice, $\ensuremath{\alpha}$ is expected to align with one of three high-symmetry directions corresponding to the in-plane nearest-neighbor bonds, consistent with a ${Z}_{3}$-Potts nematic transition. Here, we show that the nematic coupling to the acoustic phonons, which makes the nematic correlation length tend to diverge along certain directions only, can fundamentally alter this phenomenology in trigonal lattices. Compared to hexagonal lattices, the former possesses a sixth independent elastic constant ${c}_{14}$ due to the fact that the in-plane shear strain doublet $({\ensuremath{\epsilon}}_{xx}\ensuremath{-}{\ensuremath{\epsilon}}_{yy},\ensuremath{-}2{\ensuremath{\epsilon}}_{xy})$ and the out-of-plane shear strain doublet $(2{\ensuremath{\epsilon}}_{yz},\ensuremath{-}2{\ensuremath{\epsilon}}_{zx})$ transform as the same irreducible representation. We find that, when ${c}_{14}$ overcomes a threshold value, which is expected to be the case in doped ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$, the nematic director $\ensuremath{\alpha}$ unlocks from the high-symmetry directions due to the competition between the quadratic phonon-mediated interaction and the cubic nematic anharmonicity. This implies the breaking of the residual in-plane twofold rotational symmetry (${C}_{2x}$), resulting in a triclinic phase. We discuss the implications of these findings for the structure of nematic domains, for the shape of the in-plane ${H}_{c2}$ in ${A}_{x}{\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$, and for the presence of nodes inside the superconducting state.

Conservation of currents in reduced full-F electromagnetic kinetic and fluid models

In this paper, we present an analysis of the conservation of currents in a full-F electromagnetic gyro-kinetic model in the long-wavelength limit. This equation corresponds to what is usually called the ‘vorticity equation’, which is not strictly correct as it cannot be formulated as the curl of a velocity equation. In the paper, we will therefore use the term ‘current conservation equation’ instead. Our results are relevant to reduced plasma descriptions like gyro-kinetic, drift-kinetic, gyro-fluid and drift-fluid models for tokamaks and stellarators. The equation describes the change of the polarization charge density (often called ‘vorticity’) in terms of the polarization stress due to the flow, external sources and three currents: the parallel current, the curvature current and a current related to the magnetic field fluctuations. We compare this equation with previous drift- and gyro-fluid equations and find general agreement, except in the vorticity source terms where previous drift-fluid models fail to capture the heating and density sources. We discuss the role of currents in the dynamics of diamagnetic and flow shear. The possible connection between these currents with phenomena observed in experiments that influence the radial electric field in the edge of tokamak plasmas, like resonant magnetic perturbations, and different magnetic field configurations and shapes, is presented.

Terahertz electron paramagnetic resonance generalized spectroscopic ellipsometry: The magnetic response of the nitrogen defect in 4H-SiC

We report on terahertz (THz) electron paramagnetic resonance generalized spectroscopic ellipsometry (THz-EPR-GSE). Measurements of field and frequency dependencies of magnetic response due to spin transitions associated with nitrogen defects in 4H-SiC are shown as an example. THz-EPR-GSE dispenses with the need of a cavity, permits independently scanning field and frequency parameters, and does not require field or frequency modulation. We investigate spin transitions of hexagonal (h) and cubic (k) coordinated nitrogen including coupling with its nuclear spin (I = 1), and we propose a model approach for the magnetic susceptibility to account for the spin transitions. From the THz-EPR-GSE measurements, we can fully determine polarization properties of the spin transitions, and we can obtain the k coordinated nitrogen g and hyperfine splitting parameters using magnetic field and frequency dependent Lorentzian oscillator line shape functions. Magnetic-field line broadening presently obscures access to h parameters. We show that measurements of THz-EPR-GSE at positive and negative fields differ fundamentally and hence provide additional information. We propose frequency-scanning THz-EPR-GSE as a versatile method to study properties of spins in solid state materials.

Magnetic field design in a cylindrical high-permeability shield: The combination of simple building blocks and a genetic algorithm

Magnetically sensitive experiments and newly developed quantum technologies with integrated high-permeability magnetic shields require increasing control of their magnetic field environment and reductions in size, weight, power, and cost. However, magnetic fields generated by active components are distorted by high-permeability magnetic shielding, particularly when they are close to the shield’s surface. Here, we present an efficient design methodology for creating desired static magnetic field profiles by using discrete coils electromagnetically coupled to a cylindrical passive magnetic shield. We utilize a modified Green’s function solution that accounts for the interior boundary conditions on a closed finite-length high-permeability cylindrical magnetic shield and determine simplified expressions when a cylindrical coil approaches the interior surface of the shield. We use an analytic formulation of simple discrete building blocks to provide a complete discrete coil basis to generate any physically attainable magnetic field inside the shield. We then use a genetic algorithm to find optimized discrete coil structures composed of this basis. We use our methodology to generate an improved linear axial gradient field, dBz/dz, and a transverse bias field, Bx. These optimized structures generate the desired fields with less than 1% error in volumes seven and three times greater in spatial extent than equivalent unoptimized standard configurations. This coil design method can be used to optimize active–passive magnetic field shaping systems that are compact and simple to manufacture, enabling accurate control of magnetic field changes in spatially confined experiments at low cost.

Monte Carlo investigation of electron fluence perturbation in MRI-guided radiotherapy beams using six commercial radiation detectors

With the integration of treatments with MRI-linacs to the clinical workflow, the understanding and characterization of detector response in reference dosimetry in magnetic fields are required. The external magnetic field perturbs the electron fluence. The degree of perturbation depends on the irradiation conditions and on the detector type. The purpose of this study is to evaluate the magnetic field impact on the electron fluence spectra in several detectors to provide a deeper understanding of detector response in these conditions. Monte Carlo calculations of the electron fluence are performed in six detectors (solid-state: PTW60012 and PTW60019, ionization chambers: PTW30013, PTW31010, PTW31021, and PTW31022) in water and irradiated by a 7 MV FFF photon beam with a small and a reference field, at 0 and 1.5 T. Three chamber axis orientations are investigated: parallel or perpendicular (either the Lorentz force pointing towards the stem or the tip) to the magnetic field and always perpendicular to the photon beam. One orientation for the solid-state detector is studied: parallel to the photon beam and perpendicular to the magnetic field. Additionally, electron fluence spectra are calculated in modified detector geometries to identify the underlying physical mechanisms behind the fluence perturbations. The total electron fluence in the Farmer chamber varies up to 1.24% and 5.12% at 1.5 T, in the parallel and perpendicular orientation, respectively. The interplay between the gyration radius and the Farmer chamber cavity length significantly affects the electron fluence in the perpendicular orientation. For the small-cavity chambers, the maximal variation in total electron fluence is 0.19% in the parallel orientation for the reference field. Significant small-field effects occur in these chambers; the magnetic field reduces the total electron fluence (with respect to the no field case) between 9.86% and 14.50%, depending on the orientation. The magnetic field strongly impacted the solid-state detectors in both field sizes, probably due to the high-Z components and cavity density. The maximal reductions of total electron fluence are 15.06 ± 0.09% (silicon) and 16.00 ± 0.07% (microDiamond). This work provides insights into detector response in magnetic fields by illustrating the interplay between several factors causing dosimetric perturbation effects: (1) chamber and magnetic field orientation, (2) cavity size and shape, (3) extracameral components, (4) air gaps and their asymmetry, (5) electron energy. Low-energy electron trajectories are more susceptible to change in magnetic fields, and are associated with detector response perturbation. Detectors with higher density and high-Z extracameral components exhibit more significant perturbations in the presence of a magnetic field, regardless of field size.

Analysis and Implementation of 3D Magnetic Field Shaping via a 2D Planar Transmitting Coil Array

Wireless power transfer (WPT) systems operating at several MHz are known to be advantageous for realizing high spatial freedom of power transfer and compact and lightweight designs. The combined use of multiple transmitting (Tx) coils for magnetic field shaping is expected to further increase the spatial freedom. This article studies an extendable planar Tx-coil array architecture. This architecture provides new conveniences for the MHz WPT systems to efficiently charge devices in 3D space. Time-domain and phasor-domain modelings are carried out in turn to analyze the magnetic field shaping effect under the current phase shift modulation of the Tx coils. An overlap design of the Tx-coil layout is also developed to minimize the cross coupling between the coils, which reduces the interference between Tx coils. Finally, the above concepts are experimentally implemented. The results clearly demonstrate the new advantages of the planar Tx-coil array-based magnetic field shaping, in terms of spatial freedom of the power transfer, efficiency, and output power capability, when charging receivers with six-degrees-of-freedom positions and orientations in 3D space. For instance, a perpendicular receiver in the center of the Tx-coil array can be charged with 82% dc–dc efficiency and 45 W, which is difficult for a conventional single Tx-coil solution.

The Effect of Magnetic Field and Nanoparticle Shape on Heat Transfer in an Inclined Cavity with Uniform Heat Generation/Absorption

The Effect of Magnetic Field and Nanoparticle Shape on Heat Transfer in an Inclined Cavity with Uniform Heat Generation/Absorption

The Effect of The Shape of Magnetic Field on the Viability of Endothelial Cells

Purpose: Magnetic field is one of the effective and non-invasive modalities on biology and angiogenesis. Studies on the effects of magnetic fields on angiogenesis showed that the shape of the magnetic field could potentially affect angiogenesis. Therefore, this study aimed to control the frequency, intensity, and duration of exposure of magnetic field while investigating the effect of the shape of the magnetic field on the viability of Human Umbilical Vein Endothelial Cells (HUVECs). Materials and Methods: The HUVECs were exposed to various shapes of 50 and 60 Hz magnetic fields with intensities of 0.5 and 1 mT in acute and chronic exposure regimes. The viability of HUVECs was assessed via MTT assay. Results: Results showed that the sin type 50 and 60 Hz magnetic fields are more effective in decreasing the viability. The rectified 100 and 120 Hz with 1 and 0.5 mT could increase and decrease the viability compared with 50 and 60 Hz, respectively. Conclusion: It can be concluded that the shape of the magnetic field can be an effective factor in biology and must be controlled to have a reliable response.

What was the shape of the Moon's ancient magnetic field?

What was the shape of the Moon's ancient magnetic field?