Magnetic Dipole Research Articles

Research on the defect depth detection for pipeline steel with double defects using metal magnetic memory method

Metal magnetic memory testing is an effective method to detect the stress state of ferromagnetic materials, and shows great application potential in the field of defect detection of oil and gas pipelines recently. In this paper, the correlation between the normal component of residual magnetic field (RMF) and the defect depth, as well as the applied loading were investigated by tensile tests. The X70 pipeline steels were processed into specimens with double defects of six types of depths and three types of spacings. Some magnetic parameters are defined to characterize the distortion of the RMF in the defect area. The effect of defect depth and applied loading on the magnetic parameters is discussed. The RMF signals measured on the smooth side of the specimens were compared with those on the defective side. Results show that the normal parameters, obtained from the front and back of the specimens, are capable of detecting the defect depth. The slope of the linear relationship between the two increases with the increase of defect spacing. The expressions of normal magnetic parameters were derived based on the Jiles model and magnetic dipole model. The simulation results of defective side and smooth side were compared, as well as the simulation results of different defect spacing. The experimental and numerical simulation results show that the defect depth of pipeline steel can be evaluated by the characteristic parameters of the normal RMF signal under a certain stress level.

Design of a 3 T REBCO Dipole Magnet Considering Screening Current Induced Magnetic Field and its First Test Result at 77 K

Design of a 3 T REBCO Dipole Magnet Considering Screening Current Induced Magnetic Field and its First Test Result at 77 K

Optimization stability and performance of the TPS storage ring dipole magnet power supply

This article focuses on the current status of the dipole magnet power supply (DMPS) and improvement in the Taiwan Photon Source (TPS) storage ring. The DMPS provides a stable and precise magnetic field for the storage ring operation. Appropriate wiring methods are employed to minimize magnetic field interference across the entire TPS area to meet the demands of high-energy output and overcome the challenges of operating at high currents. The target energy is set at 850 V and 750 A, utilizing a single-pole switching voltage regulator as a high-precision constant current source output structure. The system incorporates a closed control loop that uses the Direct Current Current Transducer (DCCT) to provide current signal feedback to the system. FPGA (Field-Programmable Gate Array) calculates PID (Proportional-Integral-Derivative) compensation values, generating a 2.1 kHz pulse width modulation (PWM) signal to regulate the output current. At the same time, insulated gate bipolar transistor (IGBT) modules are switching components. However, even after several years of practical operation, the stability and performance of the DMPS in the storage ring still require improvements. To enhance long-term output current stability and address peripheral issues, the current TPS utilizes the Beam Orbit Feedback (FOFB) system to suppress and fine-tune the magnetic field and compensate for the impact of temperature drift on the DMPS's output current. This improvement ensures a more stable circulation of the photon beam within the storage ring. By optimizing the temperature control circuit of the main control card, the long-term output current stability has been successfully enhanced to within ± 10 ppm. Simultaneously, the FOFB system reduces uncertainties in adjusting the X-axis beam position, improving beam stability and quality. Furthermore, relevant protective measures have been implemented to ensure robust system operation. Ultimately, these improvement measures have successfully met TPS's stringent requirements for the DMPS, enabling the synchrotron accelerator light source to operate at higher performance levels and fostering advanced scientific research. The results of these upgrades underscore the success of the power supply enhancements, making significant contributions to the overall improvement of the Taiwan Photon Source facility.

Numerical Study of Plasma Characteristics Under Magnetohydrodynamic Flow Control in Mars Entry

Magnetohydrodynamic flow control is an active thermal protection method for atmospheric entry vehicles. This study examined the plasma characteristics under magnetohydrodynamic flow control and its thermal protection ability at multiple altitudes (20–60 km) on a typical direct Mars entry path using numerical simulation considering the Hall effect. The simulation considered a spherical-conical capsule with an entry velocity of 8 km/s at an altitude of 60 km, equipped with a dipole magnet generating a magnetic field of approximately 0.3 T at the stagnation point of the capsule. The results showed that magnetohydrodynamic flow control can mitigate convective aerodynamic heating at high altitudes (45 km or more), where the high electrical conductivity of the plasma creates strong magnetohydrodynamic interaction. In contrast, at low altitudes (35 km or less), magnetohydrodynamic flow control is ineffective owing to low electrical conductivity. The high electrical conductivity at high altitudes is attributed not only to large flight velocities under low atmospheric pressures but also to the enlargement of the shock layer owing to the strong magnetohydrodynamic interaction, which expands the ionization progression area. Furthermore, the results indicated that considering the Hall effect in the numerical modeling of magnetohydrodynamic flow control in Mars direct entry is essential.

Energy and dynamics analysis of a single plucking energy harvester for transient-motion-powered IoT applications

This study focuses on a piezo-magneto-elastic structure comprising an economical piezoelectric cantilever and a magnet pair. It is designed for efficient mechanical energy harvesting to power a battery-free motion-sensing IoT system through plucking motions. We conduct a thorough analysis and parametric study to elucidate the energy and dynamic intricacies during operation, specifically under a single plucking excitation. Beginning with a magnetic dipole–dipole model, we present a potential energy profile to intuitively elucidate and quantitatively assess the energy progression throughout a single plucking transient. By meticulously adjusting the setup parameters, the input potential energy can be precisely tuned, ensuring that the energy harvested from a single plucking motion meets the demand of each round of wireless communication. Diverging from previous power-centric investigations of plucking energy harvesters, in which continuous plucking motions are investigated, our approach provides a new perspective on the energy-centric design and transient dynamics of a single plucking motion. The importance of the energy-matching concept considering the subsequent energy-driven electronic modules is emphasized. This insight offers valuable design principles for the effective energy-centric co-design of cyber-electromechanically coupled self-powered IoT systems.

Photons in Physics with real Magnetic Charges and the Falsity Existing Notion of Expansion Universe (How Physicists; "Yawn" Real Magnetic Charges, Curved Space and Sentenced the Universe to Expansion)

The experiments of F. Ehrenhaft as well as the experimental and theoretical studies of the author showed that it is magnetic charges are the direct sources of the magnetic field. Eddy currents of magnetic charges (rotating magnetic dipoles g- - g+) which actually exist in atoms and substance, are untwisted by electric current in conductors, are direct sources of the well-known vortex magnetic field rotH. Together with electric charges, magnetic charges make up the shells of atoms, which are actually electromagnetic, not electronic. It is the electromagnetic shells of atoms that are the sources of the vortex electromagnetic (gravitational) field, which is described by the vortex vector rot[E – H]. The vector character of GF is in many respects similar to the vortex magnetic field, which has been known for hundreds of years, but no one has come up with the version of spatial magnetic waves. Therefore, the notion of gravitational waves, according to the author, is another fake, inspired by crooked physics, in which there is absolutely no representation of the real physics of the gravitational field. The introduction of real magnetic charges into the basic physical representations, as well as the discovery by the author of the World Physical Triad, made it possible to clarify the essence of spinor fields which are flows of elementary particles of the world Energo-medium, which are formed by spinor (charged) particles. In addition, the article proves that the concept of the expansion of the Universe was the result of E. Hubble's erroneous (extremely superficial) perception, back in 1929, of the manifestation of the cosmological redshift of the photon frequency, which he interpreted as a Doppler shift in the frequency of the so-called light waves. The inclusion of real magnetic charges in the physical representations showed that the frequency processes in photons are determined exclusively by the intra-photon physics embedded in into at the moment of formation and cannot be the result of any spatial wave formations in the environment, i.e. the shifts of photonic frequency ∆ω have nothing to do with the Doppler effect and depend only on changes in the translational velocity of their source. In other words, the redshift of the photon frequency under the conditions of the translational motion of their sources is exactly the same, both in the case of the source moving to the observer, and in the case of its movement at the same speed away from the observer. As for the violet shift of the photon frequency, this is an unambiguous sign of the rotational dynamics of photon source, and in the case of combined motion of source (translational and rotational), the mechanism of photon frequency pulsations is possible.

Muon-induced nuclear magnetic moments in spinless muonic atoms: a simple estimate

In an attempt to address the long-standing fine-structure puzzle in heavy muonic atoms we investigate the magnetic interaction between a nucleus and its bound muon. A simple estimate shows that the effect is only noticeable for unrealistic nuclear parameters. A further investigation as to the relation of this effect to nuclear polarisation (NP) identifies the interaction as the magnetic dipole part of NP. Motivated by the relative closeness of this simple estimate to rigorous evaluations of NP, we extract effective values for the nuclear magnetic polarisability, a quantity otherwise unknown for all but the lightest nuclei.

Enhanced second harmonic generation from supercavity mode and magnetic resonance in dumbbell-shaped silicon nanoblock

Abstract Electromagnetic multipole resonance can be excited by dielectric nanostructures of appropriate size to effectively promote light-matter interaction. The interactions between light and nanostructures have the capability to enhance the electromagnetic field in the near field, thereby improving the nonlinear effect of nanostructures. We illustrate that the supercavity mode and magnetic dipole resonance are activated by a single dumbbell-shaped silicon nanoblock (DS-SiNB), to trap the near-field electromagnetic field energy. Enhanced second harmonic generation is achieved by exploiting the localized electromagnetic field at the surface of the nanostructure. Numerical simulations reveal that magnetic quadrupole (MQ) and total electric dipole (TED) can be coupled to the same radiation channel by adjusting continuously the aspect ratio Lout/Ly (the outer edge length to the length of DS-SiNB) of the nanoblock. When the aspect ratio Lout/Ly = 1, the supercavity mode formed by the interference of MQ and TED is excited at λ1 = 1124 nm. And, the strong magnetic resonance mode formed by the coupling of two magnetic dipoles (MD) in the same direction is also excited at λ2 = 1124 nm. Supercavity mode and strong magnetic dipole resonance can effectively capture electromagnetic fields on the surface of nanostructures to attain enhanced second harmonic generation (SHG). Our study presents a novel approach to enhance the nonlinear optical effect of a single silicon nanostructure, which can lead to the development of more efficient nonlinear optical devices.

Chiral Spectroscopy of Bulk Systems with Propagated Localized Orbitals.

We present approaches for the simulation of electronic circular dichroism, Raman, and Raman optical activity (ROA) spectra for isolated and periodic systems as well as subsystem analysis thereof. The method is based on the use of time-dependent maximally localized Wannier functions in the CP2K package and accounts for origin dependencies inherent to the Gaussian and plane wave with pseudopotentials approach as well as the origin dependence of the magnetic dipole and electric quadrupole operators. Tests on the H-bonded enantiomers of alanine by harmonic normal-mode analysis and on an aqueous solution of l-alanine by ab initio molecular dynamics obeying periodic boundary conditions (PBCs) are presented as total and subsystem-resolved spectra. To our knowledge, this is the first instance of an ROA spectrum derived from real-time propagation obeying PBCs and the first ROA simulation considering off-, pre-, and on-resonance effects within PBCs.

Study on the static normal force of MRF in non-uniform magnetic field

Nowadays, many scholars have been studied the normal force of MRF in the uniform magnetic field. However, the research on the normal force of MRF in the non-uniform magnetic field is relatively limited. The non-uniform magnetic field can cause the MRF to generate normal force of different sizes and directions to cope with different working conditions, thus the normal force generated in the non-uniform magnetic field require more attention. In this paper, a theoretical model of the normal force of MRF in the non-uniform magnetic field was developed based on the enhanced magnetic dipole model. The normal force of MRF within a unit area can be calculated based on this theoretical model. However, the magnetic induction intensity is different at different locations of the non-uniform magnetic field, which leads to the normal force generated by the MRF are not accurately calculated. Therefore, it is necessary to use COMSOL to establish the material model of the MCR-302 plate rheometer and MRF to verify the accuracy of the proposed model. Then a flat-plate rheometer was used to test the static normal force of the MRF in the non-uniform magnetic field. Finally, the simulation and experimental data were compared. The results show that the simulation result with the experimental data is a good agreement, which verifies the reliability of the theoretical model. The static normal force of the MRF increases with the increase of volume fraction and magnetic field intensity.

Theoretical analysis of blood based ternary hybrid nanofluid under the influence of magnetic dipole with variable fluid properties

Theoretical analysis of blood based ternary hybrid nanofluid under the influence of magnetic dipole with variable fluid properties

Application of β-NMR to spectroscopy and imaging

Nuclear magnetic resonance (NMR) using β-decay radioisotopes, known as “β-NMR,” is used for research in nuclear physics. Recently, nuclear magnetic moments of β-decay radioisotopes have been precisely measured by β-NMR. Therefore, β-decay radioisotopes can be used for NMR spectroscopy in material sciences. Nuclei, whose spin is zero, such as 12C and 16O, cannot be used in conventional NMR. However, nonzero-spin radioactive isotopes of carbon and oxygen can be used in β-NMR. This advantage is powerful for investigating organic materials that cannot be investigated using conventional NMR. A technique is being developed to extend β-NMR for imaging use in magnetic resonance imaging (MRI). In this study, the imaging function was realized by installing β-ray tracking detectors in a β-NMR device. Nuclear-spin-polarized radioisotopes were injected into a sample, and β-rays were emitted from their positions. Consequently, one could track back β-ray source positions on the sample. These detectors were installed into a dipole magnet to observe the magnetic resonances. A radio frequency coil was installed surrounding the sample. By combining information about the β-ray tracks and magnetic resonances, it was possible to obtain NMR spectra and images. This method is called “β-MRI.” The system was evaluated, and its performances were estimated.

Dynamics of non-Newtonian methanol conveying aluminium alloy over a rotating disc: consideration of variable nanoparticle radius and inter-particle spacing

The advancement of non-Newtonian nanofluid innovation is a crucial area of research for physicists, mathematicians, manufacturers, and materials scientists. In engineering and industries, the fluid velocity caused by rotating device and nanofluid has a lot of applications such as refrigerators, chips, heat ex-changers, hybrid mechanical motors, food development, and so on. Due to the tremendous usage of the non-Newtonian nanofluid, the originality of the current study is to explore the influence of nanoparticle radii and inter-particle spacing effects on the flow characteristics of Casson methanol-based aluminium alloy (AA7072) nanofluid through a rotating disc with Joule heating and magnetic dipole. The present problem is modeled in the form of partial differential equations (PDEs), and these PDEs are converted into ordinary differential equations with the help of suitable similarity transformations. The analytical solution to the current modeled problem has been obtained by using the homotopy analysis method (HAM) and numerical solutions are obtained by employing Runge–Kutta–Fehlberg method along with shooting technique. The main purpose of the present research work is to analyze the behavior of the velocity and temperature of the nanofluid for small and large radius of the aluminium alloy (AA7072) nanoparticles and inter-particle spacing. The radial and tangential velocities are enhanced due to rising ferro-hydrodynamic interaction parameter and the skin friction force for radial and tangential directions are enhanced 10.51% and 2.16% when h = 0.5. Also, the heat transfer rate is reduced 18.71% and 16.70% when h = 0.5% and R p = 1.5. In fact, the present results are compared with the published results and they met good agreement.

Quantum Size-Driven Spectral Variations in Pillar[n]arene Systems: A Density Functional Theory and Wave Function Assessment.

This study explores the quantum size effects on the optical properties of pillar[n]arene (n = 5, 6, 7, 8) utilizing density functional theory (DFT) and wave function analysis. The mechanisms of electron transitions in one-photon absorption (OPA) and two-photon absorption (TPA) spectra are investigated, alongside the calculation of electron circular dichroism (ECD) for these systems. Transition Density Matrix (TDM) and electron-hole pair density maps are employed to study the electron excitation characteristics, unveiling a notable size dependency. Analysis of the transition electric dipole moment (TEDM) and the transition magnetic dipole moment (TMDM) reveals the electromagnetic interaction mechanism within pillar[n]arene. Raman spectra computations further elucidate vibrational modes, while interactions with external environments are studied using electrostatic potential (ESP) analysis, and electron delocalization is assessed under an external magnetic field, providing insights into the magnetically induced current phenomena within these supramolecular structures. The thermal stability of pillar[n]arene was investigated by ab initio molecular dynamics (AIMD).

Systematic study of magnetic and antimagnetic rotational bands

The magnetic and antimagnetic rotational bands are systematically investigated in the present work. Up to now, 253 magnetic rotational bands and 40 antimagnetic rotational bands have been reported in 123 nuclei and 29 nuclei, respectively. The experimental data for these bands are collected and collated, including the level energy, γ-ray energies, spin I, magnetic dipole reduced transition probability B(M1), electric quadrupole reduced transition probability B(E2), B(M1)/B(E2), and J (2)/B(E2), etc. In addition, following the presentation of the kinematic moment-of-inertia J (1), dynamic moment-of-inertia J (2), and I versus rotational frequency ω, as well as energy staggering parameter S(I), B(M1), B(E2), B(M1)/B(E2), and J (2)/B(E2) versus I in A ∼ 60, 80, 110, 140, and 190 mass regions, a discussion is provided in detail. Based on the systematic studies, the main features of magnetic and antimagnetic rotational bands are summarized. Furthermore, some nuclei are also predicted to be candidates for magnetic or antimagnetic rotation.

Achieving Strong Circularly Polarized Luminescence through Cascade Cationic Insertion in Lead-free Hybrid Metal Halides.

Generating circularly polarized luminescence (CPL) with simultaneous high photoluminescence quantum yield (PLQY) and dissymmetry factor (glum) is difficult due to usually unmatched electric transition dipole moment (μ) and magnetic transition dipole moment (m) of materials. Herein we tackle this issue by playing a "cascade cationic insertion" trick to achieve strong CPL (with PLQY of ~100 %) in lead-free metal halides with high glum values reaching -2.3×10-2 without using any chiral inducers. Achiral solvents of hydrochloric acid (HCl) and N, N-dimethylformamide (DMF) infiltrate the crystal lattice via asymmetric hydrogen bonding, distorting the perovskite structure to induce the "intrinsic" chirality. Surprisingly, additional insertion of Cs+ cation to substitute partial (CH3)2NH2 + transforms the chiral space group to achiral but the crystal maintains chiroptical activity. Further doping of Sb3+ stimulates strong photoluminescence as a result of self-trapped excitons (STEs) formation without disturbing the crystal framework. The chiral perovskites of indium-antimony chlorides embedded on LEDs chips demonstrate promising potential as CPL emitters. Our work presents rare cases of chiroptical activity of highly luminescent perovskites from only achiral building blocks via spontaneous resolution as a result of symmetry breaking.

Achieving Strong Circularly Polarized Luminescence through Cascade Cationic Insertion in Lead‐free Hybrid Metal Halides

AbstractGenerating circularly polarized luminescence (CPL) with simultaneous high photoluminescence quantum yield (PLQY) and dissymmetry factor (glum) is difficult due to usually unmatched electric transition dipole moment (μ) and magnetic transition dipole moment (m) of materials. Herein we tackle this issue by playing a “cascade cationic insertion” trick to achieve strong CPL (with PLQY of ~100 %) in lead‐free metal halides with high glum values reaching −2.3×10−2 without using any chiral inducers. Achiral solvents of hydrochloric acid (HCl) and N, N‐dimethylformamide (DMF) infiltrate the crystal lattice via asymmetric hydrogen bonding, distorting the perovskite structure to induce the “intrinsic” chirality. Surprisingly, additional insertion of Cs+ cation to substitute partial (CH3)2NH2+ transforms the chiral space group to achiral but the crystal maintains chiroptical activity. Further doping of Sb3+ stimulates strong photoluminescence as a result of self‐trapped excitons (STEs) formation without disturbing the crystal framework. The chiral perovskites of indium‐antimony chlorides embedded on LEDs chips demonstrate promising potential as CPL emitters. Our work presents rare cases of chiroptical activity of highly luminescent perovskites from only achiral building blocks via spontaneous resolution as a result of symmetry breaking.

Thickness- and Field-Dependent Magnetic Domain Evolution in van der Waals Fe3GaTe2.

The discovery of room-temperature ferromagnetism in van der Waals (vdW) materials opens new avenues for exploring low-dimensional magnetism and its applications in spintronics. Recently, the observation of the room-temperature topological Hall effect in the vdW ferromagnet Fe3GaTe2 suggests the possible existence of room-temperature skyrmions, yet skyrmions have not been directly observed. In this study, real-space imaging was employed to investigate the domain evolution of the labyrinth and skyrmion structure. First, Néel-type skyrmions can be created at room temperature. In addition, the influence of flake thickness and external magnetic field (during field cooling) on both labyrinth domains and the skyrmion lattice is unveiled. Due to the competition between magnetic anisotropy and dipole interactions, the specimen thickness significantly influences the density of skyrmions. These findings demonstrate that Fe3GaTe2 can host room-temperature skyrmions of various sizes, opening up avenues for further study of magnetic topological textures at room temperature.

Study of Electron Energy Distribution Function, Transport Parameters and Instability Analysis of Argon Plasma confined by a Dipole Magnet

This theoretical study is to investigate production and properties of plasma confined by a dipole magnet. A cylindrical permanent magnet (N40 grade) having a surface magnetic field of nearly 1Tesla is simulated to create a dipole magnetic field. Plasma is created by electron cyclotron resonance heating. Heating is accomplished using microwaves operating in continuous mode at 2.45 GHz and electron cyclotron resonance. The investigation is performed in systems of cylindrical geometries at varying pressures (0.5 mTorr – 1.5 mTorr). The electron temperature lies in the range of 1 - 5 eV, is hotter near the magnets and follows a downstream fashion throughout the region.Electron Energy Distribution Function (EEDF) growth investigation throughout the region was done to understand the role of magnetic field confinement. The EEDF was calculated numerically from steady state Boltzmann equation, considering plasma follows druyvesteyn distribution. Followed by analysing transport parameters such as diffusion coefficient, drift velocity, mobility, and recombination rates in plasma. A comparative study for all plots gave been done with respect to pressure. The instability analysis of elastic collisional frequency with inelastic collisions, real frequency and growth factor with wave vector has been also listed in the study.

Calculation of forbidden transitions in doubly ionized neodymium (Nd III) of interest for kilonova nebular phase analysis

In this paper, we present new radiative rate calculations for forbidden transitions, namely magnetic dipole (M1) and electric quadrupole (E2) transitions, involving all the experimentally known energy levels within the 4f4 ground configuration of doubly ionized neodymium (Nd III). To do this, and in order to estimate the accuracy of the results obtained, two independent computational approaches based on the pseudo-relativistic Hartree–Fock and the fully relativistic Dirac-Hartree–Fock methods were used. The transition probabilities calculated with these two approaches showed good overall agreement, in particular for the most intense forbidden lines for which the relative differences did not exceed 25%. From these new atomic data, some astrophysical implications were deduced such as the possibility (or not) of observing some [Nd III] lines on the infrared spectra recorded by the James Webb Space Telescope, more precisely for the analysis of nebular phase kilonova spectra following compact object mergers.