Pulsed Magnetic Field Research Articles

Electromechanical behavior of a rectangular bulk superconductor with an inhomogeneous critical current density under pulsed-field magnetization

Bulk high-temperature superconductors are widely used in various superconducting devices for their high critical current density and the ability to trap large magnetic field. In some applications, bulk superconductors can be arranged in an array structure to increase the magnetic field strength. However, rectangular bulk superconductors can be arranged more compactly than commonly used cylindrical bulk superconductors. The unique shape of rectangular bulk superconductors results in different distributions of electromagnetic fields, temperature, and stress under a pulsed-field magnetization (PFM) than for cylindrical bulk superconductors. In bulk superconductors, growth sector boundaries and growth sector regions have different critical current density, resulting in an uneven critical current density. Therefore, in this study, the electromagnetic and mechanical behavior of non-uniform rectangular bulk superconductors during the PFM process is investigated. The corresponding distribution and variation in the magnetic field, current, temperature, and stress in the bulk are calculated and analyzed. The influence of rectangle aspect ratio on the electromagnetic and mechanical behavior is discussed. The calculation results show that the magnetic flux jumps occur accompanied by sudden changes in the temperature and pressure. The effect of the aspect ratio of rectangular bulk superconductors on their electromagnetic and mechanical properties is analyzed. The influence of preexisting cracks in a non-uniform rectangular bulk superconductor on the simulation results is discussed. The numerical results indicate that the presence of an edge crack exacerbates the magnetic flux jump as well as the jumps in the temperature and stress. However, a central crack has a relatively small effect on the stability of a bulk superconductor.

Investigation of the influence mechanism of shield on the strong magnetic field during electromagnetic launch

The electromagnetic launch process generates low-frequency pulsed magnetic fields with peak values reaching Tesla-levels, imposing greater demands on the interference immunity of electronics within projectiles. However, during the propagation of low-frequency pulsed strong magnetic fields, their characteristics are affected by the shielding properties of the surrounding medium materials, resulting in modifications to the actual internal magnetic fields of the devices. This paper presents a theoretical analysis, numerical simulation, and experimental investigation based on the shielding mechanisms of conductive and magnetic materials to elucidate their impact on the pulsed magnetic fields. Additionally, leveraging previous work on electromagnetic railgun projectile magnetic field calculations, the shielding model is established to determine the shielding effects of different material combinations on the magnetic field during electromagnetic launch. The results reveal that both conductive and magnetic materials influence the amplitude, pulse width, and initiation time of the pulsed magnetic field, a finding validated through dynamic projectile-borne magnetic field testing.

Tailoring microstructure, mechanical and wear properties of Mn5Si3 reinforced Cu−35Zn−3Al alloy via melt superheat combined with pulsed magnetic field

The effects of melt superheat and pulsed magnetic field on the microstructure, mechanical and wear properties of the Mn5Si3 reinforced Cu−35Zn−3Al alloy were investigated. The results indicate that after the combined treatments, the hollow formation on the prism-shaped Mn5Si3 particles is inhibited, due to the enhanced solute migration in melt and promoted adsorption kinetics for crystal growth. The tensile strength and elongation of the forged alloy increase by 9.0% and 66.5%, respectively. The failure type of Mn5Si3 particles during tension transfers from brittle cleavage fracture to pulling out of the matrix due to the higher fracture strength with diminished stress concentration, which leads to enhanced reinforcement of matrix/particle load transfer. The wear resistance of alloy is significantly improved because of reduced delamination wear, since the severe shear fracture on the Mn5Si3 particles with hollows under friction induced plastic deformation is restrained, alleviating the subsurface originated crack propagation and spalling.

Mutagenic Effect during Combined Exposure to Ionizing and Non-Ionizing Electromagnetic Radiation.

Using the method of dominant lethal mutations, we assessed the frequency of the death of Drosophila melanogaster embryos under combined exposure to ionizing γ-radiation and non-ionizing pulsed magnetic field at various doses and modes of exposure. Mutagenic effect of combined exposure is antagonistic in nature. The antagonism is more pronounced when the following mode of exposure was used: exposure to non-ionizing pulsed magnetic field for 5 h followed by exposure to γ-radiation at doses of 3, 10, and 60 Gy. In case of reverse sequence of exposures, the antagonistic effect was statistically significant after exposure to γ-radiation at doses of 3 and 10 Gy, whereas at a dose of 20 Gy, a synergistic interaction was noted.

Effectiveness of Sanatorium Treatment Programs for Women with Chronic Endometritis: a Prospective Randomized Study

INTRODUCTION. The problem of recurrent antibiotic-resistant urogenital infections is increasing, and standard therapy is becoming ineffective. Sanatorium-resort treatment of chronic inflammatory diseases of the pelvic organs in women allows us to solve these problems with the help of natural and preformed physical factors.
 AIM. To study the clinical effectiveness of comprehensive sanatorium treatment programs in patients with chronic endometritis.
 MATERIALS AND METHODS. A prospective randomized trial included 73 patients, aged 35 ± 10 years, diagnosed with chronic endometritis. The control group (n = 25) received «basic» therapy with amplipulstherapy, sodium chloride baths. The comparison group (n = 24) received «basic» therapy and manual therapy. The main group (n = 24) received «basic» therapy, high-intensity pulsed magnetic field and manual therapy. Diagnostic criteria: immunohistochemical examination of the endometrium, echographic examination, dopplerometry of pelvic vessels, laser Doppler flowmetry.
 RESULTS AND DISCUSSION. After treatment, an increase in the uterine arterial perfusion index was noted in all groups compared with baseline values. The median indicator increased in the study groups by 2.36 times, 2.4 times, and 2.6 times, respectively (p 0.05). The decrease in the maximum peak speed in the comparison group and the main group exceeded the indicators of the control group (p 0.001). The systolic-diastolic ratio decreased in the comparison group and the main group (p 0.05). A decrease in stagnation in the venular microcirculation, a normotonic type of microcirculation, improvement in endothelial function (p 0.01) were revealed in the main group.
 CONCLUSION. An algorithm has been developed. In case of endometrial hypoplasia, decreased uterine perfusion, increased uterine artery resistance index, «basic» therapy is recommended, including sodium chloride baths and amplipulstherapy. With an increase in the maximum peak blood flow rate, an increase in the systolic-diastolic ratio, it is necessary to add a course of manual therapy to the «basic» therapy. When detecting violations of venous outflow, it is recommended to include high-intensity pulsed magnetic therapy.

Wide-field Fourier magnetic imaging with electron spins in diamond

Wide-field magnetic imaging based on nitrogen-vacancy (NV) centers in diamond has been shown the applicability in material and biological science. However, the spatial resolution is limited by the optical diffraction limit (>200 nm) due to the optical real-space localization and readout of NV centers. Here, we report the wide-field Fourier magnetic imaging technique to improve spatial resolution beyond the optical diffraction limit while maintaining the large field of view. Our method relies on wide-field pulsed magnetic field gradient encoding of NV spins and Fourier transform under pixel-dependent spatial filters. We have improved spatial resolution by a factor of 20 compared to the optical resolution and demonstrated the wide-field super-resolution magnetic imaging of a gradient magnetic field. This technique paves a way for efficient magnetic imaging of large-scale fine structures at the nanoscale.

Improved corrosion and cavitation erosion resistance of laser-based powder bed fusion produced Ti-6Al-4V alloy by pulsed magnetic field treatment

The application of pulsed magnetic field (PMF) treatment demonstrated enhanced corrosion resistance in saline solution and prolonged resistance to cavitation erosion in deionised water for Ti-6AI-4V alloy manufactured by laser-based powder bed fusion (LPBF) and conventional wrought processing methods. The observed outcomes were attributed to the formation of a denser protective surface oxide layer and microstructural changes, resulting in a reduction of the α' phase by 0.13% and an increase in the presence of dislocations at the surface. Consequently, this led to an increase in the compressive residual stresses. Additionally, the application of this treatment resulted in the formation of highly refined and uniform precipitates, leading to a notable enhancement in microhardness by 5.73% and 5.85% for the conventionally manufactured (CM) and LPBF samples, respectively.

Observation of pinning and pinning evasion dynamics of a magnetic vortex core

An understanding of the dynamics of magnetic textures as they interact with defects in the host material is critical for proposed applications that depend on controlled translation of these magnetic textures. We report on the experimental observation of magnetic vortex core (VC) trajectories as they are affected by a potential energy landscape arising from defects in thin, permalloy disks. We first map the VC pinning landscape using equilibrium Kerr microscopy, and then use multiplexed time-resolved Kerr microscopy to track in-plane dynamics of a magnetic VC in response to a magnetic field pulse with ns time resolution, and several-nm spatial resolution. The initial position of the VC is set by applying a static magnetic field to shift the dynamics relative to the pinning landscape. We observe the expected spiral trajectory as the VC relaxes to equilibrium over several tens of nanoseconds. However, in the presence of strong pinning, we also observe pinning evasion as the VC trajectory is deflected due to the pinning potential, and enhanced damping as the vortex becomes pinned. We compare to a simple model based on the Thiele equation of motion to understand these results.

Control of the memory cell magnetization by a combined pulse of local magnetic fields

We study the process of controlling the states of a magnetic memory cell by a pulsed magnetic field. The magnetization dynamics of such a system is described by the Landau-Lifshitz equation. We find the optimal parameters of time dependence, amplitude and duration of magnetic field pulses created by currents in the control system, which provide a fast inertialess process of switching the magnetization of the functional element of the cell.

Birthplace of ball lightning

Examples of ball lightning formation at high altitude near a linear lightning channel are considered. A photograph of ball lightning emerging from a linear lightning channel is shown. It is shown that the process of ball lightning formation lasts no more than 30 ms. A model of ball lightning formation due to the action of a magnetic field pulse of a linear lightning current on the ionized volume of space is described. A scheme has been proposed to explain a rare event - the gathering of ball lightning from sparks. Cases of the formation of ball lightning at a large distance from the site of a linear lightning strike, when energy was transferred through wires, are considered. It is noted that the process of formation of such ball lightning and their properties differ markedly from ball lightning appearing near the channel of linear lightning. This made it possible to distinguish these objects into a special type of ball lightning. A model of the process of formation of such ball lightning is described, according to which their core consists of ions flowing from the electrode of an air electrical capacitor (antenna, power line), and the shell material is dust particles. Cases of observation of objects with a size of 50 microns - 1 mm appearing during electrical discharges in water are considered. The analogy of these objects with miniature ball lightning is shown.

Tesla-class single-cycle terahertz magnetic field pulses generated with a spiral-shaped metal microstructure

Abstract We study the terahertz (THz) magnetic field pulse enhanced by a spiral-shaped antenna resonator (SAR). We deposit the SAR on the surface of a terbium-gallium-garnet crystal, which has a large Verdet constant, and measure the Faraday rotation angle for strong THz pulse excitation by magneto-optical sampling (MOS) with near-infrared light. The determined magnetic field strength and field-enhancement spectrum are consistent with the theoretical predictions. This first report of the detection of the magnetic field of a Tesla-class picosecond pulse by magneto-optical sampling is expected to be useful in research on the control of magnetization in spintronic devices.

Shubnikov–de Haas oscillations of biaxial-strain-tuned superconductors in pulsed magnetic field up to 60 T

Two-dimensional (2D) materials have gained increasing prominence not only in fundamental research but also in daily applications. However, to fully harness their potential, it is crucial to optimize their properties with an external parameter and track the electronic structure simultaneously. Magnetotransport over a wide magnetic field range is a powerful method to probe the electronic structure and, for metallic 2D materials, quantum oscillations superimposed on the transport signals encode Fermi surface parameters. In this manuscript, we utilize biaxial strain as an external tuning parameter and investigate the effects of strain on the electronic properties of two quasi-2D superconductors, MoTe2 and RbV3Sb5, by measuring their magnetoresistance in pulsed magnetic fields up to 60 T. With a careful selection of insulating substrates, we demonstrate the possibility of both the compressive and tensile biaxial strains imposed on MoTe2 and RbV3Sb5, respectively. For both systems, the applied strain has led to superconducting critical temperature enhancement compared to their free-standing counterparts, proving the effectiveness of this biaxial strain method at cryogenic temperatures. Clear quantum oscillations in the magnetoresistance—the Shubnikov–de Haas (SdH) effect—are obtained in both samples. In strained MoTe2, the magnetoresistance exhibits a nearly quadratic dependence on the magnetic field and remains non-saturating even at the highest field, whereas in strained RbV3Sb5, two SdH frequencies showed a substantial enhancement in effective mass values, hinting at a possible enhancement of charge fluctuations. Our results demonstrate that combining biaxial strain and pulsed magnetic field paves the way for studying 2D materials under unprecedented conditions.

CHANGES IN THE STRUCTURE AND PHASE STATE OF ALUMINUM ALLOY 2014, WHICH OCCURRED AS A RESULT OF IRRADIATION WITH AN ELECTRON BEAM

The use of aluminum alloys in nuclear power is limited by the properties of these alloys in the irradiation zone. The use of electron accelerators is an effective technique for simulating real operating conditions. As a result of irradiation, a whole complex of factors begins to work in the targets, which change the properties of these targets. Pulsed electric and magnetic fields appear, shock waves are generated, and gradient heating occurs. All this together changes the structure and properties of the targets. To irradiate the samples, electron beams with an energy of 8.2...8.3 MeV and a beam current of 0.8 mA were used. The work studied changes in the structural-phase state of an aluminum alloy of type 2014. For samples, before and after irradiation, an analysis of changes in mechanical characteristics (hardness, ultimate strength, proof strength) was carried out. Diffractometric studies were performed. These studies made it possible to determine changes in the phase composition. The intensity values of the diffraction lines were obtained.

Il1r2 and Tnfrsf12a in transcranial magnetic stimulation effect of ischemic stroke via bioinformatics analysis.

Ischemic stroke refers to ischemic necrosis or softening of localized brain tissue. Transcranial magnetic stimulation (TMS) is a painless, noninvasive and green treatment method, which acts on the central nervous system through a pulsed magnetic field to assist in the treatment of central nervous system injury diseases. However, the role of Il1r2 and Tnfrsf12a in this is unknown. The ischemic stroke datasets GSE81302 and TMS datasets GSE230148 were downloaded from Gene Expression Omnibus database. Differentially expressed genes (DEGs) were screened and weighted gene co-expression network analysis (WGCNA) was performed. The construction and analysis of protein-protein interaction (PPI) network and functional enrichment analysis were performed. Draw heat map gene expression. Through the Comparative Toxicogenomics Database (CTD) to find the most relevant and core gene diseases. TargetScan was used to screen miRNAs regulating DEGs. A total of 39 DEGs were identified. According to gene ontology (GO) analysis results, in biological process (BP) analysis, they were mainly enriched in the positive regulation of apoptosis process, inflammatory response, positive regulation of p38MAPK cascade, and regulation of cell cycle. In cellular component (CC) analysis, they were mainly enriched in the cell surface, cytoplasm, and extracellular space. In Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, they were mainly enriched in nf-κB signaling pathway, fluid shear stress and atherosclerosis, P53 signaling pathway, TNF signaling pathway, and apoptosis. Among the enrichment items of metascape, negative regulation of T cell activation, hematopoietic cell lineage, positive regulation of apoptotic process, fluid shear stress and atherosclerosis were observed in GO enrichment items. Five core genes (Socs3, Irf1, Il1r2, Ccr1, and Tnfrsf12a) were obtained, which were highly expressed in ischemic stroke samples. Il1r2 and Tnfrsf12a were lowly expressed in TMS samples. CTD analysis found that the core gene (Socs3, Irf1 and Il1r2, Ccr1, Tnfrsf12a) and ischemic stroke, atherosclerosis, hypertension, hyperlipidemia, thrombosis, stroke, myocardial ischemia, myocardial infarction, and inflammation. Il1r2 and Tnfrsf12a are highly expressed in ischemic stroke, but lowly expressed in TMS samples.

Magnetic properties and magnetocaloric effect of DyCo9Si4

Polycrystalline samples of DyCo9Si4 with the tetragonal LaFe9Si4-type structure have been synthesized by arc melting and high-temperature annealing. Results of the magnetization M and specific heat Cp measurements show the existence of two magnetic anomalies at TC = 40 K and Tm = 20 K. The transition at TC = 40 K is attributed to the ferromagnetic transition of the Co sublattice. The magnetic moments of Dy3+ appear to align gradually below TC, and almost fixed below Tm, at which a broad maximum in Cp has been observed. Field-dependent M at T = 2 K up to H = 7 T suggested that the magnetic moment of Dy3+ is coupled antiferromagnetically with those of Co, forming a ferrimagnetic structure. Magnetization measurements up to 50 T at low temperatures using a pulse magnet demonstrated a spin-flip transition around H = 20 T, above which the magnetic moments of Co and Dy are in parallel. The spin-flip transition becomes broad with increasing temperature but still remains at TC = 40 K, indicating a strong antiparallel coupling between Co and Dy moments even in the paramagnetic state. The magnetocaloric effect was evaluated from Cp and M, and also from the sample-temperature variation in the quasi-adiabatic process with the pulsed magnetic field. The maximum entropy change for the field change from 5 to 0 T was observed at around T = Tm with the value ΔS = 5 J/kg K. The maximum temperature of ΔS shifts to higher temperatures in high magnetic fields, resulting in the large value of ΔS = 24 J/kg K at T ∼ TC by the field change from 50 to 0 T. The present results demonstrate that the pulsed-field measurement is a powerful method to evaluate the magnetocaloric effect of materials.

Influence of the pulsed magnetic field of the amplitude strength on the parameters of the magnetoplastic effect in aged Al–Si–Cu–Fe aluminum alloy

The results of a comprehensive experimental study of the influence of the pulsed magnetic field of the amplitude strength on the properties and characteristics of an Al–Si–Cu–Fe aluminum alloy during aging are presented. Data are presented on the modes of thermomagnetic treatment and the results of measurements of the microhardness, lattice parameter, and fine structure parameters of the alloy aged at a temperature of 175°С for 4 h in a pulsed magnetic field with a strength amplitude of 79.6–557.2 kA/m and in its absence. The main regularities of changes in the structure and properties of the metal alloy during annealing are formulated.

Comparison of the cytogenetic effects of a pulsed magnetic field and gamma radiation on meristem cells of onion seed sprouts (Allium cepa l.)

The effect of a pulsed magnetic field (PMF) on meristem cells of onion seedlings was compared with the effects of acute gamma irradiation using the allium test. It was found that a pulse with a carrier frequency of 1.8 MHz, a pulse repetition rate of 28 kHz, and a magnetic field induction of 75 mT per pulse leads to an increase in the mitotic index, mainly due to an increase in the proportion of cells in the prophase, an increase in the frequency of cells with chromosome aberrations in the ana-telophase and does not affect the frequency of cells with micronuclei. It has been suggested that UTI causes nonspecific oxidative stress in plant cells, accompanied by a delay in the cell cycle at the check point (G2/M) and induction of DNA damage. According to these indicators, the PMF resembles the effect of ionizing radiation in doses of 0.05–0.5 Gy.

RANDOMIZED COHORT CONTROL STUDY COMPARING THE USE OF STANDARD THERAPY VERSUS STANDARD THERAPY PLUS “SUPER INDUCTIVE MAGNETIC SYSTEM” IN THE TREATMENT OF MUSCULOSKELETAL INJURIES

The pulsed electromagnetic field (PEMF) is considered a promising innovative means in physiotherapy and medicine. The method has wide range of therapeutic effects that address mainly musculoskeletal and neurological disorders. The application of electromagnetic fields (EMF) in medicine has a long history. Magnetic fields (MF) were created by passing electric currents through a wire coil placed above the fracture. Through Faraday induction, periodic variations in the MF created the appropriate electrical field in bone [1]. The biological effects of pulsed MF on nerve tissue have received significant study in recent decades [2]. The aim of this study was to evaluate the efficacy of Super Inductive Magnetic system in people with musculoskeletal pain. SIS therapy was compared with standard therapy. Statistical analysis showed that the difference between groups was significant (p < 0.001), which proves that SIS therapy is more effective compared to standard therapy. SIS is safe and effective method for treatment of musculoskeletal pain. Further investigations need to be done to provide more accurate data and to evaluate the effectiveness of this method compared to other treatment methods.

Magnetic field treatment effects on microstructure and properties of A356 aluminium alloy

This study investigates the impact of pulsed magnetic fields (33 mT) under varying ageing temperatures (175, 185 and 195 °C) on α-Al grains, secondary phases and mechanical properties of A356 aluminium alloy. Results show that magnetic field ageing treatment can not only refines α-Al grains and promotes Si particle precipitation, but also improves the size and morphology of eutectic Si. The optimal α-Al grain refinement post-magnetic field treatment is observed at an ageing temperature of 195 °C. Meanwhile, the ultimate tensile strength and yield strength values were recorded at 345 and 283 MPa, respectively. The magnetic field ageing treatment exerts a dual influence: it accelerates atom diffusion, fostering the precipitation of reinforcing phases and simultaneously refines alloy grains, increasing the grain boundaries.

The study of grain transport effects on grain refinement under pulsed magnetic fields

The motion of grains within the molten metal under a pulsed magnetic field influences the influx of grains, thereby impacting the refinement of the solidification structure of metal. Physical simulation experiments, solidification studies, numerical simulations, and theoretical analyses are combined to investigate the motion patterns of grains in molten metal subjected to a pulsed magnetic field in the case of identical power. The findings suggest that grain movement occurs in two primary phases: initially, within the non-flow area at the solid-liquid interface, where grains respond to electromagnetic forces, and subsequently, within the flow area where the molten metal carries the grains. The speed of grain transport in the flow area directly influences the movement of grains in the non-flow area, then affecting the refinement of the metal solidification structure. The study introduces the concept of "transport characteristic time" to quantify the transport capacity of grains within the flow area, which enables a quantitative analysis of refinement effect under identical power conditions.