Strong Magnetic Field Environment Research Articles

3D spatially-confined magnetic anodes towards advanced lithium ion batteries

Magnetic transition-metal oxides show great prospect as alternatives to prevail anodic carbonaceous substances for lithium ion battery in virtue of their splendid theoretical capacity. However, in addition to their intrinsic poor electronic conductivity, the severe agglomeration of the forming magnetic metal nanoparticles during discharging will deteriorate their actual electrochemical performance in a strong magnetic field environment. Here, we demonstrate a 3D spatially-confining magnetic anode to settle all these dilemmas, in which conversion-type magnetic Fe3O4 nanoparticles with a thin carbon encapsulation layer are anchoring onto 3D nickel nanotube arrays skeleton (Ni/Fe3O4@C NTAs). The carbon shell spatially confines the agglomeration of Fe nanoparticles and maintains the exceptional integrity of structure. The Ni/Fe3O4@C NTAs anode exhibits high-capacity lithium storage (∼1286 mAh g−1 at 0.1 C) and superior rate/cycle capability (retaining ∼97 % of initial reversible value at 1 C after long-term 1000 cycles).

GRB 211211A: a Prolonged Central Engine under a Strong Magnetic Field Environment

Recently, a kilonova-associated gamma-ray burst (GRB 211211A), whose light curve consists of a precursor (∼0.2 s), a hard spiky emission (∼10 s), and a soft long extended emission (∼40 s), has attracted great attention. Kilonova association could prove its merger origin, while the detection of the precursor can be used to infer at least one highly magnetized neutron star (NS) being involved in the merger. In this case, a strong magnetic flux Φ is expected to surround the central engine of GRB 211211A. Here we suggest that when Φ is large enough, the accretion flow could be halted far from the innermost stable radius, which will significantly prolong the lifetime of the accretion process, and so the GRB duration. For example, we show that as long as the central black hole (BH) is surrounded by a strong magnetic flux Φ ∼ 1029cm2 G, an accretion flow with could be halted at 40 times the gravitational radius and be slowly transferred into the black hole on the order of ∼10 s, which naturally explains the duration of hard spiky emission. After most of the disk mass has been accreted onto the BH, the inflow rate will be reduced, so a long and soft extended emission is expected when a new balance between the magnetic field and the accretion current is reconstructed at a larger radius. Our results further support that the special behavior of GRB 211211A is mainly due to the strong magnetic field of its progenitor stars.

Magnetic field influence analysis on the large-caliber steady-state magnetic field testing system.

The large-caliber steady-state magnetic field testing system is an important device for the International Thermonuclear Experimental Reactor, which is mainly used for electromagnetic compatibility tests in a strong magnetic field environment. Magnetic field performance is the most important parameter of equipment. In the design process, it is necessary to analyze the magnetic field performance and study the influencing factors. This paper mainly studies the axial and radial magnetic fields in the uniform region and the magnetic field characteristics in several typical cases and then analyzes the influence of external ferromagnetic materials and the environmental magnetic field in detail. Finally, an experimental platform is built for a three-dimensional hall test. The results verify the correctness of the analysis.

Magnetoelectric Design of Simulation System for Strong Magnetic Field Environment

How to design an impact platform that can provide a strong electromagnetic environment for all kinds of precision electronic equipment and experimental reference for strong electromagnetic protection is of great significance. In this article, an electromagnetic coil system that generated a strong magnetic field environment was designed and studied. First, the coil parameters and coil structure were designed. Then, the Comsol finite element software was used to simulate and design the three-component coil. The coil distance and turns were adjusted to make the coil center produce a uniform magnetic field area and meet the strong magnetic field index. Finally, the coil system was built to verify the magnetic field generated by the coil through experiments. This system will be used to simulate the strong magnetic field environment that produces different high precision and may occur in the operating environment of the equipment. It will also be used to provide strong magnetic field impact test support conditions for aerospace, naval vessels, and various types of equipment, so as to find and solve the problem of antistrong magnetic reliability of equipment in the design stage.

Structural design and seismic calculation of the magnetic field immunity testing system

The magnetic field immunity testing system is an important equipment for ITER (the International Thermonuclear Experimental Reactor), which is mainly used for electromagnetic compatibility test in strong magnetic field environment. Due to the large size of the system, the stability of the structure should be considered under the action of electromagnetic force and gravity. In this paper, the electromagnetic load distribution of the system under steady-state condition is analyzed by using the finite element method, and the force of each component in different directions is calculated. Then the reasonable fixed structure is designed to ensure the stable operation of the equipment, and the electromagnetic structure coupling analysis is used for the final fixed structure to study the electromagnetic force, gravity and bolt preload. Finally, the stress analysis of the equipment under the influence of seismic load is calculated. The results show that the system has enough seismic capacity.

An improved measurement scheme of the large-caliber steady-state magnetic-field testing system for ITER

The large-caliber steady-state magnetic-field testing system is an important device for the International Thermonuclear Experimental Reactor, which is mainly used for electromagnetic compatibility tests in a strong magnetic field environment. The uniform magnetic field area needs to be measured to ensure the correctness of the design after the completion of the platform. This paper mainly analyzes the relationship between the magnetic field probe and error, studies the detection effect of different arrangement methods of magnetic field probe points, and obtains a more accurate probe arrangement method through comparative analysis. Then, the principle and structure of the acquisition and detection system are studied, and the multipoint synchronous Hall array magnetic field detection system of the magnetic field is built by using the Hall probe to realize the omnidirectional measurement of the magnetic field. Finally, the Hall probe is calibrated and tested by experiments, and a test platform is built to test the magnetic field. The results verify the correctness of the analysis.

Effect of tungsten armor on electromagnetic characteristics of blanket for the fusion device under plasma disruption

Tungsten armors are arranged on the plasma side of the blankets to protect the first wall in a fusion device, such as China Fusion Engineering Test Reactor (CFETR) and European Demonstration Power Plant (EU DEMO). Tungsten armors will produce a huge eddy current and Electromagnetic (EM) load under plasma disruption due to their high conductivity and strong magnetic field environment, which will cause the blankets to be subjected to a substantial eddy current and thus heat load, thermal stress and mechanical stress, that potential could damage blankets. To evaluate the effect of the tungsten armor on the electromagnetic characteristics of blanket, electromagnetic calculation method verification is carried out. And the electromagnetic finite element model of blanket is established by using ANSYS, and the eddy current distribution in the first wall is calculated. Effects of the tungsten armor, split size and gap size of the tungsten armor on the eddy current of blanket first wall and effect of the tungsten armor on the EM force of blanket are researched. And the influence of different tungsten armor design on the thermal stress distribution of blanket first wall is also studied. The study results will provide an important reference for the blanket design of the fusion device.

Analysis and design of the induction coil for a 2.1 m / 120 mT magnetic field qualification test facility

Equipment mounted around tokamak devices are usually exposed to high intensity magnetic field and suffers from severe interference problems. To qualify the operation reliability of sensitive devices under strong magnetic field environment, a magnetic field qualification test facility was designed and built in Chinese Academy of Sciences, Institute of Plasma Physics (ASIPP). This paper presents the analysis and design of the induction coil for this test facility. At first, a field homogeneity analysis is performed and an optimized three-coil configuration with minimum power loss and conductor mass is obtained. Then, the electrical, structural and cooling designs are conducted and verified by finite element analysis. At last, error field analysis is performed to evaluate the influence of installation misalignment. The designed induction coil is capable of generating a homogeneous magnetic field with a field inhomogeneity of 1.2 in a 2.1 m side-length cubic zone. The test facility enables the qualification test for the devices with a maximum dimension within 2.1 m and at a highest nominal test level of 120 m T. Further, the optimization design method can be extended to the design of some other fusion auxiliary devices.

Power supply for on-line monitoring device of power lines based on double-half ring core

In order to solve the problem of insufficient energy supply of the on-line monitoring device of the transmission line, a sensor energy acquisition scheme directly installed on the transmission line is proposed. In the current power supply, induction power supply is a kind of energy extraction method with better practical applicability. Since the monitoring devices and electronic equipment on the transmission line are often in a strong magnetic field and high voltage environment, designing a stable and reliable power supply is the guarantee for the stable operation of the monitoring devices and electronic equipment. This paper presents a structure of energy-absorbing iron core with two semi-circular magnetic cores, and studies the magnetic saturation problem in the inductive power supply and the design of the DC output circuit.

A Method Using Magnetic Eddy Current Testing for Distinguishing ID and OD Defects of Pipelines under Saturation Magnetization

Distinguishing the inside (ID) and outside (OD) defect is an essential problem for the oil and gas pipeline nondestructive testing in engineering. The most widely used solution is to combine a magnetic flux leakage (MFL) section and a second section. For the strong magnetic field environment of the MFL, the second section and the MFL section are usually located at different mechanical positions, which leads to an increase in the length of the pipeline inspection gauge (PIG) and a decrease in the reliability. In this paper, a new impedance measurement method and the concept of the defect impedance angle are proposed to distinguish the ID and OD defects of pipelines under saturation magnetization, which based on the magnetic eddy current testing (MECT). The proposed ID & OD detection method can work with the MFL in the same mechanical position. Meanwhile, the proposed method also has the advantage that the discrimination criteria of the ID and OD defect keeps consistent with the classic eddy current testing (ECT). Furthermore, the robustness and sensitivity of the proposed method are discussed and verified by physical experiments.

Liquid metal MHD effect and heat transfer research in a rectangular duct with micro-channels under a magnetic field

The liquid metal blanket of a fusion reactor acts the role of tritium multiplication and energy transportation in a strong magnetic field environment. Liquid metal in fusion blanket is different from traditional flow and heat transfer due to magneto hydrodynamics (MHD) effects. A numerical simulation is employed to investigate the convection heat transfer between liquid metal and micro-channels heated surface under an external magnetic field. It can be found that under the influence of magnetic field, liquid metal can produce strong jet near the wall which drives the liquid metal flow together inside the channel. The MHD Hunt flow effect is intensified with the enhancement of the magnetic field and the results indicate that the magnetic field is beneficial to the energy transport and conversion of liquid metal blanket due to the jet flow on the wall that caused by the magnetic field. From the point of view of enhanced heat transfer, 32% of the heat transfer enhancement under the influence of strong magnetic field provides a new way to solve the heat transfer with high heat flux density. The expression is fitted between Nu number with Re number, the magnetic interaction number and flow distance, which can be used to predict the change of heat transfer intensity between the liquid metal and the micro-channels heated plate with the magnetic field intensity.

Geomagnetic and strong static magnetic field effects on growth and chlorophyll a fluorescence in Lemna minor.

The geomagnetic field (GMF) varies over Earth's surface and changes over time, but it is generally not considered as a factor that could influence plant growth. The effects of reduced and enhanced GMFs and a strong static magnetic field on growth and chlorophyll a (Chl a) fluorescence of Lemna minor plants were investigated under controlled conditions. A standard 7 day test was conducted in extreme geomagnetic environments of 4 µT and 100 µT as well as in a strong static magnetic field environment of 150 mT. Specific growth rates as well as slow and fast Chl a fluorescence kinetics were measured after 7 days incubation. The results, compared to those of controls, showed that the reduced GMF significantly stimulated growth rate of the total frond area in the magnetically treated plants. However, the enhanced GMF pointed towards inhibition of growth rate in exposed plants in comparison to control, but the difference was not statistically significant. This trend was not observed in the case of treatments with strong static magnetic fields. Our measurements suggest that the efficiency of photosystem II is not affected by variations in GMF. In contrast, the strong static magnetic field seems to have the potential to increase initial Chl a fluorescence and energy dissipation in Lemna minor plants.

Fast charge-sensitive preamplifier for pure CsI crystals

We have designed, built and tested a fast charge-sensitive preamplifier to be used with pure CsI crystals in a strong magnetic field environment. We measured its properties and verified that the preamplifier meets all the required specifications. With a shaping time of 50ns, we measure an energy resolution of (120±7)keV for 137Cs γ rays and an electronics energy resolution of (40±2)keV. We estimate a relatively low power dissipation of (140±5)mW.

Development of a particle injection system for impurity transport study in KSTAR.

A solid particle injection system is developed for KSTAR. The system has a compact size, compatibility with a strong magnetic field and high vacuum environment, and the capability to inject a small amount of solid particles with a narrow injection angle. The target flight-distance of 10 cm has been achieved with a particle loss rate of less than 10%. Solid impurity particles such as tungsten and carbon will be injected by this system at the midplane in KSTAR. The impurity transport feature will be studied with a soft X-ray array, a vacuum ultra-violet diagnostic, and Stand Alone Non-Corona code.

Study of isolated contact temperature monitoring system based on optical wireless sensing technology

In view of the high voltage, the strong magnetic field environment of the high-voltage switchgear, the system based on the optical wireless sensing technology, realizes the isolated contact temperature monitoring of the high-voltage switchgear. In this scheme, the good thermal conductivity and insulation ceramic materials were selected as the outer jacket material sensing probe, and the program had a good solution to the problem of high and low voltage isolation; The combination of the optical fiber composite insulators for wireless sensing, not only solves the problem of high voltage insulation, but also avoids the “creeping” phenomenon due to dust. The package of the structure and reasonable installation solves the cross sensitivity of strain. The application showed that the precision of temperature measurement of the system could reach ± 0.5 °C and could work in a variety of harsh environments. It could improve the reliability of the operation of the electrical equipment significantly and has considerable practical value for the whole power system.

Neutral pressure measured by fast ionization gauge in HL-2A

A fast ionization gauge capable of working in a strong magnetic field and noisy environment is developed for the pressure measurement in the main chamber and the divertor chamber of the HL-2A tokamak. The neutral pressure in the main chamber evidently decreases after in-situ siliconization. Improvement of boundary plasma confinement is observed with SMBI or PI fueling after siliconization. The neutral pressure in the main chamber for divertor configuration is 50% lower than that for limiter one. The pressure in the divertor chamber rises when the strike point moves toward the bottom of the vertical target plates. The maximum pressure compression of is 24. The relative high pressure in the main chamber is contributed primarily by plasma limiter interaction due to the short distance from separatrix to limiter and secondly by neutral flux from the divertor chamber to the main chamber by leaks in HL-2A.

X‐Ray Thread G0.13−0.11: A Pulsar Wind Nebula?

We have examined Chandra observations of the recently discovered X-ray thread G0.13-0.11 in the Galactic center Radio Arc region. Part of the {\sl Chandra} data was studied by Yusef-Zadeh, Law, & Wardle (2002), who reported the detection of 6.4-keV line emission in this region. We find, however, that this line emission is {\sl not} associated with G0.13-0.11. The X-ray spectra of both G0.13-0.11 and the point-like source embedded are well characterized by a power law. The 2 -- 10 keV band luminosities of these two components are $\sim 3.2\times 10^{33}{\rm ergs s^{-1}}$ (G0.13-0.11) and $\sim 7.5 \times10^{32} {\rm ergs s^{-1}}$ (point source) at the Galactic center distance of 8 kpc. The morphological, spectral, and luminosity properties strongly indicate that G0.13-0.11 represents the leading-edge of a pulsar wind nebula, produced by a pulsar (point source) moving in a strong magnetic field environment. The main body of this pulsar wind nebula is likely traced by a bow-shaped radio feature, which is apparently bordered by G0.13-0.11 and is possibly associated with the prominent nonthermal radio filaments of the Radio Arc. We speculate that young pulsars may be responsible for various unique nonthermal filamentary radio and X-ray features observed in the Galactic center region.

CHEMICAL EVOLUTION OF STRONGLY MAGNETIZED QUARK CORE IN A NEWBORN NEUTRON STAR

The chemical evolution of nascent quark matter core in a newborn compact neutron star is studied in presence of a strong magnetic field. The effective rate of strange quark production in degenerate quark matter core in presence of strong magnetic fields is obtained. The investigations show that in presence of strong magnetic field the quark matter core becomes energetically unstable and hence a first/higher order deconfinement transition to quark matter at the centre of a compact neutron star under such circumstances is absolutely impossible. The critical strength of magnetic field at the central core to make the system energetically unstable with respect to dense nuclear matter is found to be ~4.4 × 1013 G. This is the typical strength at which the Landau levels for electrons are populated. The other kind of phase transformations at such high density and ultra strong magnetic field environment are discussed.

Thermal properties and applications of high- Tc (Nd,Eu,Gd)Ba 2Cu 3O y bulk superconductors

In the newly approved Joint Research Project for Regional Intensive in Iwate ; “Development of practical application of magnetic field technology for use in the region and in everyday living”, application of magnetic field environments realized by high TC bulk superconductors is one of the main R&D subjects. Numerical analyses on scattering mechanisms in the thermal conductivity of (Nd,Eu,Gd)Ba 2Cu 3O y [NEG(123)] bulk superconductors with 10, 20, 30 mol% NEG(211) second phase (SP) were performed. We found a strong correlation between amount of added second phase and scatterings by grain boundary and Umklapp process. Performance of power leads made of [NEG(123)+30 mol%SP] bulk superconductor for strong stray magnetic field environment was also estimated.

Sound levels daring operation of magnetic resonance imaging systems

The sound or noise levels at the patient position in the bore of several different magnetic resonance imaging (MRI) systems were measured. The measurements were conducted with the microphone/preamplifier component connected to the sound-level meter (SLM) with an extension cable so that the SLM was remote from the MRI scan room. Preliminary tests and analyses were conducted to ascertain that the microphone/preamp functioned normally in the strong magnetic field and rf environment. Subsequently, A-weighted, flat-weighted, and octave band noise levels were measured in the MRI system bore areas during a variety of image scanning sequences. The noise levels were in the range 75–95 dB A-wt., and 85–105 dB flat-wt. Greater noise levels tended to be correlated with greater magnetic field strengths and with more rapid and detailed image scanning sequences.