Pulsed Magnetic Field Research Articles

Nuclear Magnetic Resonance Measurements in High Flat-Top Pulsed Magnetic Field Up to 40 T at WHMFC

Nuclear magnetic resonance (NMR) technique benefits from the high magnetic field not only due to the field-enhanced measurement sensitivity and resolution, but also because it is a powerful tool to investigate field-induced physics in modern material science. In this study, we successfully performed NMR measurements in the high flat-top pulsed magnetic field (FTPMF) up to 40 T. A two-stage corrected FTPMF with fluctuation of less than 10 mT and duration of longer than 9 ms was established. Besides, a Giga-Hz NMR spectrometer and a sample probe suitable for the pulsed-field condition were developed. Both free-induction-decay and spin-echo sequences were exploited for the measurements. The derived <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">93</sup> Nb NMR results show that the stability and homogeneity of the FTPMF reach an order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ppm / 10 ms and 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ppm / 10 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> respectively, which is approaching a degree of maturity for some researches on condensed matter physics.

Analysis of the effect magnet-pulse processing on the storage of tomato fruits

The conducted studies were aimed at assessing the impact of tomato storage methods, taking into account the extension of their shelf life and preservation of nutritional value, using the example of two varieties. The shelf life of all varieties has been increased by magnetic pulse processing (MPP) of the fruits when stored in the unpackaged variant. As a result of the studies carried out, it was found that the processing of tomatoes with MPP and storage conditions had a significant impact on the physiological weight loss of tomatoes. The parameters of magnetic pulse processing in the course of experimental studies were magnetic induction - 5 mT, frequency 32 Hz. An increase in shelf life and significant changes in quality were observed in all tomato samples stored in the MPP container, while deterioration in quality was increased in vacuum-packed tomatoes. The best storage combination was MPP in a polystyrene container, which kept the tomato fruits up to 30 days. The performed studies confirmed the possibility of effective use of a low-frequency pulsed magnetic field with the selected parameters to increase the shelf life and preserve the biochemical composition of tomatoes.

Снижение механических напряжений в тонкостенной квазибессиловой магнитной системе, внесенной во внешние скрещенные магнитные поля

The mechanical stresses in the thin-walled quasi-force-free winding of the solenoid, which arise when a strong pulsed magnetic field is produced, can be significantly reduced if the winding is inserted into the area between two magnets creating crossed fields. It is shown that with a rational choice of the amplitude and shape of the external fields pulses the stresses can be reduced to values less than one tenth of the magnetic pressure of the generated field.

The mechanical stresses reduction in a thin-walled quasi-force-free magnetic system inserted into external crossed magnetic fields

The mechanical stresses in the thin-walled quasi-force-free winding of the solenoid, which arise when a strong pulsed magnetic field is produced, can be significantly reduced if the winding is inserted into the space between two magnets creating crossed fields. It is shown that, with a rational choice of the amplitude and shape of the external field pulses, the stresses can be reduced to values less than one tenth of the magnetic pressure of the generated field. Keywords: strong magnetic fields, quasi-force-free field, force-balanced coil.

SELECTION OF A RATIONAL METHOD FOR HARDENING CARBIDE CUTTING TOOLS FOR HEAVY ENGINEERING

An important task is to improve cutting tools for high-precision productive machining of difficult-to-machine materials by applying the latest tool hardening methods. This is especially true for carbide-cutting tools. The paper analyzes the current state of the problem of improving the tooling of new machine tools for high-precision productive machining of hard-tomachine materials. The main known methods of increasing the wear resistance and strength of carbide tools can be divided into the following groups: structural methods; mechanical hardening; wearresistant coatings; chemical and thermal treatment; laser hardening; plasma-arc hardening; radiation hardening; ionic alloying; magnetic abrasive treatment; and pulsed magnetic field treatment. The choice of a particular hardening method depends on many factors that determine its effectiveness and costs in certain production conditions. The conditions for machining large-sized parts at heavy engineering enterprises are analyzed. It was found that, along with wear, the destruction of the cutting part in the form of pitting and fracture is significant. Statistical studies have proven that when machining on heavy machine tools, the cutting force allowed by the machine tool mechanisms does not limit the cutting modes. The maximumvalues of forces are up to 10 times higher than their average value, which is usually used to calculate the design parameters of cutting tools An analysis of various methods for improving the physical and mechanical properties of carbide tool materials has shown that the best combination of cost and production efficiency is observed in pulsed magnetic field treatment. The use of magnetic fields in cutting processes and tool hardening is a promising area of high-technology development in machining. Increasing tool life can be achieved by the influence of a magnetic field either on the conditions of the cutting process or on the structure and physical and mechanical properties of tool materials with ferromagnetic components.

High strain rate deformation of conductive materials with use of pulse magnetic fields

The study of metal deformation processes under extreme impacts is relevant due to the need to predict the behavior of materials in operational and critical modes using various deformation models. In this case, the key factor is to expand the range of experimentally determined/achievable parameters for their verification. The high energy density of the magnetic field and a reliable and simple technique for monitoring its parameters make it possible to use the magnetic pulse method of generating controlled pressure pulses of microsecond duration with an amplitude of ∼1 GPa. A classification of methods for high strain rate deformation of conductive materials by magnetic-pulse loading is carried out and features of magnetic-mechanical. An analysis of the experimental results showed the applicability of the magnetic-pulse method for studying plastic deformation processes with strain rates up to 104 1/s and more and the possibility to formulate requirements for the magnetic system and pulse current sources.

High Intensity Pulsed Magnetic Field Application in Patients with Chronic Prostatitis Complicated by Erectile Dysfunction: а Randomized Prospective Study

INTRODUCTION. Chronic prostatitis is one of the most common urological nosologies, the third most common diagnosis in men under 50 years old. Existing scientific sources testify to the effectiveness of various physiotherapeutic interventions in patients with infectious-inflammatory diseases of the male reproductive system, complicated by erectile dysfunction. AIM. The aim of the study was the scientific substantiation of high-intensity pulsed magnetic field application in patients with chronic prostatitis complicated by erectile dysfunction. MATERIAL AND METHODS. The study included 60 patients randomized into two groups. The first group (30 people) received high-intensity pulsed magnetic field; the second group (30 people) received drug therapy. RESULTS AND DISCUSSION. It was shown that the high clinical results of high-intensity pulsed magnetic field application were based on the compensation of local blood circulation conditioned by the improvement of the prostate blood flow according to the ultrasound of the prostatic vessels as well as by the elimination of the penile blood supply deficiency due to the improvement of the arterial vessels tone and elimination of venous stasis according to laser doppler flowmetry. CONCLUSION. An innovative method has been developed to treat patients with chronic prostatitis complicated by erectile dysfunction using high-intensity pulsed magnetic field.

Unconventional Spin State Driven Spontaneous Magnetization in a Praseodymium Iron Antimonide.

Consolidating a microscopic understanding of magnetic properties is crucial for a rational design of magnetic materials with tailored characteristics. The interplay of 3d and 4f magnetism in rare-earth transition metal antimonides is an ideal platform to search for such complex behavior. Here the synthesis, crystal growth, structure, and complex magnetic properties are reported of the new compound Pr3 Fe3 Sb7 as studied by magnetization and electrical transport measurements in static and pulsed magnetic fields up to 56T, powder neutron diffraction, and Mößbauer spectroscopy. On cooling without external magnetic field, Pr3 Fe3 Sb7 shows spontaneous magnetization, indicating a symmetry breaking without a compensating domain structure. The Fe substructure exhibits noncollinear ferromagnetic order below the Curie temperature TC ≈380 K. Two spin orientations exist, which approximately align along the Fe-Fe bond directions, one parallel to the ab plane and a second one with the moments canting away from the c axis. The Pr substructure orders below 40K, leading to a spin-reorientation transition (SRT) of the iron substructure. In low fields, the Fe and Pr magnetic moments order antiparallel to each other, which gives rise to a magnetization antiparallel to the external field. At 1.4K, the magnetization approaches saturation above 40T. The compound exhibits metallic resistivity along the c axis, with a small anomaly at the SRT.

Modification effects of the pulsed magnetic field on the coated cemented carbides tool for enhanced mechanical and cutting performances

In this study a pulsed magnetic treatment (PMT) was attempted to improve the cutting performance of the TiCN–Al2O3–TiN/cemented carbides inserts and the effects of the strength of the pulsed magnetic field on the cutting forces, tool wear, the machined surface roughness and mechanical properties were investigated. It is found that the cutting performances of the coated tools are successfully enhanced after the treatment and both the resultant force and the component force for the treated tools are considerably lower than that for the untreated one. In particular, a maximum reduction of approximately 6% in the resultant cutting force is achieved, along with a maximum reduction of 23.8% in the wear area of the flank surface after the treatment. However, the roughness of the machine surface generally shows an increasing trend with the increasing strength of the pulsed field and an increase of approximately 17.6% in the surface roughness is obtained. The hardness from the nanoindentation test indicates an approximately 23% increase after the PMT. The improvements in the cutting and mechanical performances of the coated tool are attributed to the residual stress change caused by the comprehensive effects of the reduction in the defects density within the coating and the phase transformation and magnetostriction of the cobalt within the substrate induced by the field treatment.

Bifunctional Magnetite–Gold Nanoparticles for Magneto-Mechanical Actuation and Cancer Cell Destruction

Magnetite–gold dumbbell nanoparticles are essential for biomedical applications due to the presence of two surfaces with different chemical natures and the potential combination of magnetic and plasmonic properties. Here, the remote actuation of Fe3O4-Au hybrid particles in a rotating (1 Hz, 7 mT), static (7 mT) or pulsed low-frequency (31 Hz, 175 mT, 30 s pulse/30 s pause) magnetic field was studied. The particles were synthesized by a high-temperature wet chemistry protocol and exhibited superparamagnetic properties with the saturation magnetization of 67.9 ± 3.0 Am2 kg−1. We showcased the nanoparticles’ controlled aggregation in chains (rotating/static magnetic field) in an aqueous solution and their disaggregation when the field was removed. The investigation of nanoparticle uptake by LNCaP and PC-3 cancer cells demonstrated that Fe3O4-Au hybrids mainly escaped endosomes and accumulated in the cytoplasm. A significant fraction of them still responded to a rotating magnetic field, forming short chains. The particles were not toxic to cells at concentrations up to 210 μg (Fe3O4) mL−1. However, cell viability decrease after incubation with the nanoparticles (≥70 μg mL−1) and exposure to a pulsed low-frequency magnetic field was found. We ascribe this effect to mechanically induced cell destruction. Overall, this makes Fe3O4-Au nanostructures promising candidates for intracellular actuation for future magneto-mechanical cancer therapies.

Crack nucleation and propagation of electromagneto-thermo-mechanical fracture in bulk superconductors during magnetization

Bulk high-temperature superconductors (HTS) like REBCO (RE: rare earth element or Y) have been widely adopted in a variety of engineering applications. With high magnetic flux applied in a short time of milliseconds, significant tensile stresses are induced during pulsed field magnetization by the Lorentz electromagnetic forces and Joule heating thermal expansions. Consequently, potential damage and fracture may occur in bulk HTS, leading to degradation of the capacity in trapping the magnetic field. In this multi-physical problem, due to the complex stress distribution even in the elastic stage and the intensive redistribution once crack nucleation occurs, the resulting fracture pattern is very complicated. Accordingly, it is a challenging issue to model crack nucleation and propagation of such electromagneto-thermo-mechanical fracture involving both the Lorentz electromagnetic forces and the Joule heating. In this work, the mechanical stresses and multi-physical fracture in bulk HTS during magnetization are studied systematically by the phase-field cohesive zone model (PF-CZM). The governing equations and the involved constitutive relations for the electromagnetic, thermal and cracking-mechanical sub-problems are given together with the numerical implementation. The elastic semi-analytical solutions for the Lorentz forces and thermal expansions induced stresses in an infinitely long cylindrical bulk HTS during magnetization are derived for the determination of crack nucleation. Numerical results are then discussed in details regarding the whole fracture process in bulk HTS under isothermal and non-isothermal cases. It is found that the first crack nucleation occurs at a certain interior position along the circumferential direction after which a couple of cracks nucleate and propagate outwards along the radial direction. The effects of Joule heating and cracking on the electromagnetic performances are quantified, and those of the inhomogeneity in the critical current density are also briefly discussed. Moreover, extension of the proposed PF-CZM to more complex cases is straightforward, making it a promising tool in optimizing the fabrication and practical application of bulk HTS.

Magnetic and Electric Field Dependent Charge Transfer in Perovskite/Graphene Field Effect Transistors

AbstractStable all‐inorganic CsPbX3 perovskite nanocrystals (PNCs) with high optical yield can be used in combination with graphene as photon sensors with high responsivity (up to 106 A W−1) in the VIS‐UV range. The performance of these perovskite/graphene field effect transistors (FET) is mediated by charge transfer processes at the perovskite – graphene interface. Here, the effects of high electric (up to 3000 kV cm−1) and magnetic (up to 60 T) fields applied perpendicular to the graphene plane on the charge transfer are reported. The authors demonstrate electric‐ and magnetic‐field dependent charge transfer and a slow (&gt;100 s) charge dynamics. Magneto‐transport experiments in constant (≈0.005 T s−1) and pulsed (≈1000 T s−1) magnetic fields reveal pronounced hysteresis effects in the transfer characteristics of the FET. A magnetic time is used to explain and model differences in device behavior under fast (pulsed) and slowly (continuous) changing magnetic fields. The understanding of the dynamics of the charge transfer in perovskite/graphene heterostructures developed here is relevant for exploitation of these hybrid systems in electronics and optoelectronics, including ultrasensitive photon detectors and FETs for metrology.

Direct imaging of stress-induced magnetic behavior transitions

Stress induction plays a special role in performance control for material science. So far, it has remained challenging to systematically investigate magnetoelectric effect under stress-mediated interaction. Here we constructed a magnetoelectric device with piezoelectric stress induction, in which the stress plays a crucial intermediate role during the controllable modification of the magnetic behavior transitions under the magnetic field or current pulse driven process. The compressive stress was found to make the above process easier and reduce energy consumption via changing the magnetic domain energy state. Meanwhile, both the domain distribution and domain-wall driven process are sensitive to stress intensity. Our magnetoelectric device integrated the advantages of voltage-stress and spin-current for the control of magnetic behavior transition with the help of micro-nano processing. For the stress-induced magnetic behavior in magnetic materials was directly imaged and quantificationally investigated, the complex interactions between stress, magnetic domain motion, magnetic field, and spin current have been clarified.

Technology of magnetophoresis of topical nonsteroidal anti-inflammatory drugs in osteoarthritis (clinical and experimental study)

BACKGROUND: The high degree of evidence for the use of pharmacotherapy currently does not cause doctors to doubt, however, the use of non-pharmacological approaches in general and physical factors in particular is the subject of many years of discussion for them. One of the main places in the pharmacotherapy of osteoarthritis is occupied by nonsteroidal anti-inflammatory drugs, while our interest is associated with a group of so-called topical drugs.&#x0D; AIM: In order to methodically substantiate the application of the magnetophoresis technology of the topical form of nimesulide in an experimental study, the influence of the magnetic field on the spectroscopic and thixotropic characteristics of the drug was determined, and the clinical efficacy of the combined use of magnetotherapy and the transdermal form of nimesulide in comparison with the application of the drug and magnetic therapy with a pulsed low-frequency magnetic field was determined.&#x0D; MATERIAL AND METHODS: A randomized study involving 60 patients with osteoarthritis of the knee joints was performed. The experimental part of the study on the effect of the magnetic field on the structure and properties of the gel form of the preparation containing 1% nimesulide (chemical formula: 4'-nitro-2'-phenoxy-methane sulfonanilide) was carried out in laboratory conditions. The clinical part of the study included the use of local therapy (application of nimesulide gel in an amount of 24 g) to the skin in the knee joint area, followed by the placement of inductors of the ALMAG+ magnetic therapy apparatus on the medial and lateral surfaces of the knee joint. The impact was carried out according to the recommended "3+1" program.&#x0D; RESULTS: An analysis of the effectiveness of therapy conducted in a group of 60 patients with osteoarthritis of the knee joints showed high efficiency, expediency and safety of the use of the technology under study in the treatment of patients with joint diseases.&#x0D; CONCLUSION: Due to the synergistic effect on the pathogenesis of articular syndrome, the gel form of nimesulide and the magnetic field have a unidirectional effect: anti-inflammatory, decongestant, analgesic, microcirculatory. In addition, the magnetic field enhances the absorption and flow of the drug into the tissues, being a physical enhancer (amplifier), which significantly affects the result of treatment.

A method for increasing the yield of the suitable product of humic acids from raw materials using pulse-magnetic processing

The paper studied the effect of high-intensity pulsed magnetic fields (PMF) on extraction of humic acids in order to increase the yield of the suitable product. It is proposed to add to the technological chain of reactions for the precipitation of humic acids the operation of PMF processing of raw materials at the stage of the brawn coal suspension in alkali (the first experiment) or the alkaline extraction suspension (the second experiment).Pulse-magnetic processing the brawn coal suspension in alkali and the alkaline extraction suspension was carried out at magnetic field intensities H=0.09 106 A/m and H=0.82 106 A/m with the frequency of the discharge circuit f=40 kHz and the number of pulses n=1. The experiments have shown that when humic acids are obtained by water-alkaline extraction followed by their precipitation in an acid medium, for the highest yield of the product it is necessary to add the operation of pulse-magnetic processing a raw material at the magnetic field intensity of 0.82 106 A/m at the stage of the brawn coal suspension in alkali. It can be assumed that a high-intensity PMF contributes to the transfer of humic acids to a state conducive to their more efficient precipitation and extraction.

In-vacuum Helmholtz coils for pulsed magnetic fields studying ultrafast demagnetization

The availability of sub 100 fs short and highly intense free-electron laser (FEL) pulses allows for new insights in laser-induced ultrafast demagnetization (LID) of ferromagnetic thin films on nanometer length scales. We designed a pair of in-vacuum Helmholtz coils, providing pulsed magnetic fields up to µ 0 Hz = ±45 mT, for time-resolved experiments at FEL sources in transmission geometry. We report on the implementation of the Helmholtz coils in an optical-pump–resonant-magnetic-scattering (tr-XRMS) experiment at the FEL FERMI (Elettra, Trieste) to study LID in different magnetic domain networks. We discuss the limitations for multi-shot measurements, that rely on the full reversibility of the demagnetization process in-between two pump–probe events, and emphasize the importance of reference–pump–probe schemes, especially in tr-XRMS experiments that employ external Hz fields.

Exposure to 10 Hz Pulsed Magnetic Field Induced Slight Apoptosis and Reactive Oxygen Species in Primary Human Gingival Fibroblasts.

Extremely low frequency pulsed magnetic fields (MFs) have been increasingly used as an effective method in oral therapy, but its potential impact on health has not been clarified. In this study, we investigated the impact of 10 Hz pulsed MF exposure on primary human gingival fibroblasts (HGFs) derived from eight healthy persons (four males and four females). Cells were exposed to 10 Hz pulsed MFs at 1.0 mT for 24 h. Cell apoptosis, cell cycle progression, intracellular reactive oxygen species levels, DNA damage, and cell proliferation were determined after exposure. The results showed that 10 Hz pulsed MFs exposure have slight effects on cellular apoptosis, cell cycle progression, and DNA damage in primary HGFs from some but not all samples. In addition, no significant effect was found on cell proliferation. © 2022 Bioelectromagnetics Society.

Precise pulsed magnetic field mapping using a compact pick-up probe for a pulsed sextupole magnet.

A pulsed sextupole magnet was used for beam injection at the KEK-Photon Factory (KEK-PF). During the top-up injection, oscillation of the stored beam was observed. To investigate this issue, a compact pick-up probe has been developed for measuring peak fields around the zero-magnetic-field region where the stored beam passes. The probe has two coils: a main coil and a background coil. The width and length of the main coil are only 3.2 and 5.8mm, respectively. The voltage signal from the background coil is subtracted from that of the main coil to obtain an effective voltage signal. The results show that the peak field of a pulsed magnet can be measured with a sufficient accuracy for magnetic field mapping. A magnetic field signal with an amplitude of 2.2 × 10-4 T was measured clearly. The longitudinal field structure that contains the magnetic field generated by the eddy-current effect was observed, which explains the oscillation of the stored beam at the KEK-PF.

Development of pulsed magnetic field assisted supersonic plasma spraying.

This study designs a pulsed magnetic field assisted supersonic plasma spraying (PM-SPS) device. The instrument is divided into magnetic field generation and spraying modules, and they are connected by a dual control system and professional fixture. The PM-SPS system is simple to operate and has no contact with the spraying process. In addition, it can achieve high field intensity and stable pulse frequency in a short time. It has a strengthening effect on the whole coating forming process. The porosity, roughness, hardness, and tribological properties of the coatings prepared using the PM-SPS system were improved. The reported experiments and results can be generalized to other coating applications, which require high quality surfaces.

Home-made pulse magnet power supply for magnetizing permanent magnets and magnetic measurements

In this article, we propose a home-made pulse magnetic field generation system constructed using a thyristor and large capacitance capacitors to generate high magnetic fields to investigate magnetic properties and magnetize the magnet and high-performance magnetic materials at room temperature. The proposed system produced a magnetic induction (magnetic field) μ 0 H of 15.6 T with the 33.6 mF capacitor and an excitation voltage of 600 V. Further, we designed a new power supply system and a pulse magnet using the commercially available pulse magnet and power supply. We found that the duration time of the magnetic fields (t d) and the generated magnetic fields were three and four times larger than those for a conventional system, respectively. We also performed magnetization of a NEOMAX permanent magnet; the coercivity (Β CJ) was 2.0 T, and the magnetization saturated at ∼4.0 T. These results suggest that we can magnetise a permanent magnet such as NEOMAX with strong magnetic fields using this system. Further, the magnetic measurements of these magnets can be performed as well. The merit of our system is that the capacitance of the capacitor bank is larger than that of other studies or general commercial power supplies. Therefore, relatively high magnetic fields with long duration time can be generated. We also performed experiments on the magnetization process (M-H) of Gd to investigate the magnetocaloric effect in high magnetic fields. The magnetic entropy change was comparable to the result of former investigation. We believe that our research can contribute to the development of permanent magnets and magnetic materials for scientific and industrial use because our system allows the generation of strong magnetic fields at room temperature.