Effects Of Magnetic Field Intensity Research Articles

Magneto-Thermoelastic Principal Parameter Resonance of a Functionally Graded Cylindrical Shell with Axial Tension

The principal parameter resonance of a ferromagnetic functionally graded (FG) cylindrical shell under the action of axial time-varying tension in magnetic and temperature fields is investigated. The temperature dependence of physical parameters for functionally graded materials (FGMs) is considered. Meanwhile, the tension bending coupling effect is eliminated by introducing the physical neutral surface. The kinetic and strain energies are gained with the Kirchhoff–Love shell theory. Based on the nonlinear magnetization characteristics of ferromagnetic materials, the electromagnetic force acting on the shell is calculated. The nonlinear vibration equations are obtained through Hamilton’s principle. Afterward, the vibration equations are discretized and solved by Galerkin and multiscale methods, respectively. The stability criterion for steady-state motion is established utilizing Lyapunov stability theory. After example analysis, the effects of magnetic field intensity, temperature and power law index on the static deflection are elucidated. Subsequently, the impacts of these parameters, as well as axial tension, on the amplitude-frequency characteristics, resonance amplitude, and multiple solution regions are discussed explicitly. Results indicate that the stiffness can be enhanced due to the generation of static deflection. The amplitude decreases with increasing magnetic field intensity, temperature, and power law index. When the magnetic field intensity surpasses a threshold, the resonance phenomenon disappears.

Effects of the applied fields' strength on the plasma behavior and processes in E × B plasma discharges of various propellants. II. Magnetic field

The effects of magnetic field intensity on the properties of the plasma discharge and on the underlying phenomena are studied for different propellants' ion mass. The plasma setup represents a 2D radial–azimuthal configuration with perpendicular electric and magnetic fields. The electric field is along the axial direction, and the magnetic field is along the radial direction. The magnetic field intensity is changed from 5 to 30 mT, with 5 mT increments. The studied propellant gases are xenon, krypton, and argon. The simulations are carried out using a reduced-order particle-in-cell code. It is shown that, for all the propellants, the change in the magnetic field intensity yields two distinct plasma regimes, where either the modified two-stream instability (MTSI) or the electron cyclotron drift instability (ECDI) are dominant. A third plasma regime is also observed for cases with moderate values of the magnetic field (15 and 20 mT), where the ECDI and the MTSI co-exist with comparable amplitudes. This described variation of plasma regime becomes clearly reflected in the radial distribution of the axial electron current density and the electron temperature anisotropy. At the relatively low-magnetic-field intensities (5 and 10 mT), the MTSI is mitigated. At relatively high magnitudes of the magnetic field (25 and 30 mT), the MTSI becomes strongly present, a long-wavelength wave mode develops, and the ECDI becomes suppressed. An exception to this latter observation was noticed for xenon, for which the ECDI was observed to be detectable with a notable strength up to the magnetic field value of 25 mT.

Effect of applied electric and magnetic fields on surface roughness in minimum quantity lubrication turning using Fe3O4 nano-ferrofluid

PurposeFirst, the effect of magnetic field intensity and nano-ferrofluid concentrations on surface roughness was evaluated in magnetic minimum quantity lubrication (MMQL). Then, the effect of lubricant flow rate and nozzle position on surface roughness was investigated in MQL, MMQL, electrostatic MQL (EMQL) and electromagnetic MQL (EMMQL).Design/methodology/approachThis study examined the performance of MQL under magnetic and electric fields in turning AISI 304 stainless steel in terms of surface roughness and compared the results with those obtained from wet cutting and MQL turning operations. To prepare the nano-ferrofluid used in different states of MQL, Fe3O4 nanoparticles were added to the base fluid.FindingsThe results showed that the surface roughness under the EMMQL technique decreased by 36% and 49.4% on average compared with wet and MQL techniques, respectively. The lubrication technique affected the surface roughness by 90.2%, whereas it was 8.3% for the lubricant flow rate. EMQL and EMMQL techniques had no significant difference in their effects on surface roughness. In the innovative MMQL technique, the nano-ferrofluid concentration of 6% and magnetic field intensity of 93 G resulted in lower surface roughness of the workpiece relative to other counterparts.Originality/valueExamining previously published studies showed that using nano-ferrofluids under a magnetic field for cooling purposes in machining processes have less considered by researchers. This study applies an innovative method of lubrication under the concurrent effect of magnetic and electric fields, called EMMQL, to improve the efficiency of MQL in machining hard-to-cut materials. For comprehensively inspecting the newly presented method, the effects of several parameters, including the nano-ferrofluid concentration, magnetic field intensity, lubricant flow rate and position of lubricant spray nozzle, on the surface roughness of workpiece in turning of AISI 304 stainless steel are investigated.

Experimental Investigation on Viscosity Change of Waxy Crude Oil Emulsion with Magnetic Field

The rheological properties of emulsions are complex, leading to serious flow assurance issues that affect the economical and safe operation of pipelines. It has been reported that applying magnetic treatment technology can effectively improve the flowability of waxy crude oil. The study aims to investigate the influence of magnetic treatment on the viscosity of waxy crude oil emulsions. A dynamic electromagnetic treatment device was designed. The dynamic magnetic treatment experiments of waxy crude oil emulsion were carried out to explore the effects of magnetic field intensity and magnetic field frequency on the viscosity change of waxy crude oil emulsion. Research results show that with four different magnetic field frequencies, the viscosity of the emulsion decreases initially and then increases with the increase in magnetic field intensity. The variation law of emulsion viscosity with magnetic field intensity is related to the magnetic field frequency. When the magnetic field frequency is 100 Hz, the highest and lowest viscosity variation rates are 7.91% and -7.36%, respectively, which occur at the magnetic field strength of 110 mT and 30 mT, respectively. It is believed that applying a higher field strength electromagnetic field to the emulsion is beneficial for viscosity reduction. The research findings can provide guidance for the further study of the viscosity reduction of waxy crude oil emulsion magnetic treatment technology.

Effect of magnetic field intensity on friction and wear of TiN- and TiCN-coated neodymium magnets

Numerous machinery components are constantly influenced by magnetic fields, mainly because of the environments in which they operate. In addition, these components show different friction and wear characteristics throughout their lifetime because of their operating conditions. Here, the tribological characteristics of magnetized materials were investigated. The magnet specimens consisted of a neodymium magnet, which is one of the strongest magnets, coated with TiN or TiCN. Sliding tests were conducted with a ball-on-disk-type tester. The tribological properties of magnetized samples were compared considering their different coating conditions. The wear amount was measured under constant load and cycle conditions. The measured wear amount was used to evaluate the specimens’ tribological characteristics. One of the important factors affecting the wear and friction properties is the magnetic flux density and the formation of an oxidative transfer layer under a magnetic field. Samples subjected to a magnetic field showed better wear resistance as a result of a magnetic effect that resulted in debris being oxidized at the rubbing interface, which reduced debris production. These results can be used to evaluate the reliability of mechanical components exposed to a magnetic field.

Effect of magnetic field intensity on the microstructure and abrasion resistance of magnetic electrodeposited Ni–Co–SiC thin films

The purpose of this work is intended to fabricate Ni–Co–SiC thin films on the surface of carbon steel bearing by magnetic electrodeposition (MED) technique. The surface morphology and composition of Ni–Co–SiC thin films were investigated by scanning electron microscope (SEM), energy disperse spectroscopy (EDS), and X-ray diffraction (XRD). The microhardness and frictional coefficient were detected by utilizing microhardness tester and ball-on-desk wear tester. The surface protrusion of Ni–Co–SiC thin films presented first descent and then ascent with the increasing magnetic field intensity. The surface morphology of Ni–Co–SiC thin films obtained at magnetic field intensity of 0.8 T presented more flat and dense than those deposited at magnetic field intensity of 0.4 and 1.2 T. Meanwhile, the highest microhardness of 987.5 Hv and lowest frictional coefficient of 0.75 were also emerged in the Ni–Co–SiC thin films fabricated at magnetic field intensity of 0.8 T. In addition, XRD results indicated the Ni–Co–SiC thin films manufactured at magnetic field intensity of 0.8 T possessed smallest Ni–Co grain size of 15.6 nm. The abrasion loss of M2 thin film was 17.3 mg, while the M1 film processed the largest abrasion loss of 31.5 mg. In addition, the average frictional coefficients of M1, M2 and M3 thin films were 1.04, 0.75 and 0.85, respectively.

Three-dimensional investigation of capture efficiency of carrier particles in a Y-shaped vessel considering non-Newtonian models

In the present study, the capture efficiency (CE) and trajectories of carrier particles in a Y-shaped vessel under the effect of a non-uniform magnetic field are investigated in three dimensions. The magnetic field is produced by a cylindrical Neodymium Iron Boron (NdFeB) magnet located outside the lower branch. Two cases are considered for the magnet: (1) magnet with zero rotation and (2) 90° rotated with double height. Two non-Newtonian models, i.e., Power-law and Carreau, are considered to model blood behavior. The effect of magnetic field intensity, blood velocity, particle diameter, and magnet positioning for all three cases, one Newtonian and two non-Newtonian models, is investigated. Besides, the effect of magnetic field and non-Newtonian models on the wall shear stress (WSS) was investigated. The results showed that increasing the blood velocity and particle diameter resulted in enhanced CE. Also, by increasing the particle diameter from 500 nm to 1500 nm, the CE for Newtonian, Power-law, and Carreau models enhanced by 74 %, 90 %, and 81 %, respectively. It was found that non-Newtonian behavior and magnetic field would increase the WSS; however, its effect on the WSS can be neglected for low magnetic field intensity. The 90° rotated with double height is the most desirable case for capturing the carrier particles.

Double-diffusive convection in a magnetic nanofluid-filled porous medium: Development and application of a nonorthogonal lattice Boltzmann model

In this work, to fill the rare reports on double-diffusive convection (DDC) considering the effects of porous medium, nanofluid, and magnetic field at the same time, we first developed a full nonorthogonal multiple-relaxation-time lattice Boltzmann (LB) model for DDC in a nanofluid-filled porous medium subjected to a magnetic field. The capability of the newly proposed model is then verified. By solving specific problems via the full model with specific control parameters, we show that the nonorthogonal LB model is accurate for handling the effects of the porous medium, nanofluid, and magnetic field. Finally, we apply the model to DDC in an Fe3O4–water nanofluid-filled porous cavity with a hot left boundary and examine the effects of magnetic field intensity and inclination angle on the flow, heat, and mass transfer inside the porous medium. Results show that heat and mass transfer can both be adjusted by varying the intensity and inclination angle of the magnetic field. When the external magnetic field is applied, the heat and mass transfer along the hot wall declines monotonously with increasing the strength of the magnetic field. In contrast, the average Nu and Sh increase at first and then decrease with the inclination angle of the magnetic field, reaching the maximum at around γ = 45°. Results in this work pave a tunable way for heat and mass transfer regulation inside a magnetic nanofluid-fill porous medium. In addition, this work provides essential reference solutions for further study on DDC in a nanofluid-filled porous medium subjected to a magnetic field.

Effect of magnetic field intensity on aerobic granulation and partial nitrification-denitrification performance

Magnetic field, acknowledged as a sustainable approach, is a promising method to improve the formation, stability and treatment performance of aerobic granular sludge (AGS). In this study, partial nitrification-denitrification was achieved in three AGS sequencing batch reactors (SBRs), and the effect of magnetic field intensity on AGS formation and partial nitrification-denitrification performance were investigated. 50 mT magnetic field could accelerate complete granulation time from 45 d (0 mT) to 30 d (50 mT) by promoting the settling ability of AGS and stimulating the secretion of extracellular polymeric substances (EPS). With 50 mT magnetic field, partial nitrification-denitrification in AGS was enhanced, and the removal efficiency of chemical oxygen demand (COD), NH4+-N and TN increased by 7.6%, 26.2% and 41.5% comparing with the control (0 mT). Magnetic field balanced the dominant genera Thauera, Flavobacterium, Chryseobacterium and Meganema, which further enhanced the aerobic granulation and partial nitrification-denitrification in AGS. Thus, the application of magnetic field is reliable for accelerating aerobic granulation and enhancing partial nitrification-denitrification process.

Oscillation behavior of bubble pair in magnetic fluid tube under magneto-acoustic complex field

Based on the dynamic model of a single bubble in a magnetic fluid tube, the dynamic equation of a bubble pair system in a magneto-acoustic field is established by introducing the secondary sound radiation between bubbles and considering the magnetic field effect of the viscosity of the magnetic fluid. The effects of magnetic field intensity, bubble pair’s size, bubble interaction (including secondary Bjerknes force <i>F</i><sub>B</sub> and magnetic attraction <i>F</i><sub>m</sub>) and fluid characteristics on the vibration characteristics of double bubbles are analyzed. The results show that magnetic field increases the amplitude of bubbles, and the influence of magnetic field on the large bubble is greater than on the small bubble. When the center distance between the two bubbles is constant and the relative size of two bubbles is larger, or when the size of the two bubbles is constant and the surface distance between two bubbles is small, the interaction between two bubbles is stronger. In the magneto-acoustic composite field, magnetic field can affect <i>F</i><sub>B</sub>, <i>F</i><sub>m</sub>, magnetic pressure <i>P</i><sub>m</sub> and viscosity resistance, and the influence degrees are different. There is competition between <i>F</i><sub>B</sub> and <i>F</i><sub>m</sub> and between <i>P</i><sub>m</sub> and viscosity resistance, and the forces acting on the microbubble jointly affect the movement of the bubbles. By studying the dynamic behavior of paired bubbles, it can provide a theoretical basis for improving the therapeutic effect of targeted regulation of microbubbles on biological tissues by adjusting the magneto-acoustic field in practical application.

Numerical investigation on turbulent flow and heat transfer characteristics of ferro-nanofluid flowing in dimpled tube under magnetic field effect

• This is the first study on dimpled tube under magnetic field effect. • Effects of dimple geometry and magnetic field on the thermal and hydrodynamic behaviour have been investigated. • The Nu enhances with increasing volume fraction of magnetic nanoparticle. • The highest PEC is obtained for Ha = 75, magnetic nanoparticle fraction of 2.5 vol% and dimpled tube with P 2 /d = 7.5. For the aim of increasing the heat transfer enhancement, a hybrid method in which active and passive heat recovery techniques have been used together. The usage of nanofluid, MHD and dimpled fins tube have not been utilized together so far. Regarding this issue, this study is the first numerical study to determine effect of usage of three effects together comprehensively. In this study, thermo-hydraulic performance of Fe 3 O 4 /H 2 O nanofluid (ferro-nanofluid) flow inside dimpled tube under magnetic field effect has been examined numerically. The main purpose of the study is to obtain numerical data for turbulent flow in the spherical dimpled tubes providing some aid to design a highly efficient thermal energy storage devices. Dimple geometry with nondimensional pitch ratio ( P/d = 3.75, 7.50 and 11.25 ), Hartmann number ( Ha = 75, 150, 225) and nanoparticle volume fraction ( φ = 0.5, 1.0 and 2.5 vol % ) are the parameters investigated in this study. The numerical analyses have been carried out Reynolds number ranging from 10,000 to 50,000 at a constant heat flux at 20 kW/m 2 . The simulations have been built up by Realizable k- ε turbulence model and single-phase approach. Also, “MagnetoHydroDynamic” ( MHD ) module has also been activated for defining magnetic field effect. The results showed that Nusselt number increases with increasing Reynolds number and decreasing pitch ratio. The dimple geometry type of P/d = 7.50 has been determined as the most efficient dimple geometry type. In the case of highest magnetic field intensity, the highest Nusselt number increment (72.48%) has been obtained for φ = 2.5 vol% compared to the base fluid of distilled water using as the working fluid for smooth tube. The highest PEC value was also obtained as 1.126 for the case of P/d = 7.5, φ = 2.5 vol% and Ha = 75. In addition, the effect of magnetic field intensity on velocity and temperature distributions has been presented with contour graphs.

Magnetic segregation behaviors of a binary mixture in fluidized beds

In industrial processes, external energy fields are used to efficiently regulate the segregation behaviors of fluidized beds containing binary mixtures. We added a magnetic field force model to the discrete element method used to numerically investigate the segregation behaviors of binary component particles in magnetic field-fluidized beds. We explored the effects of magnetic field intensity, gradient, and superficial gas velocity on the extent of segregation. Bi-dispersed particles were separated under moderate magnetic field intensities, and segregation increased as the field intensity rose. However, if the field intensity became excessive, magnetic particles tended to agglomerate, reducing segregation. Thus, control of the magnetic field gradient within a certain range is key for effective particle segregation.

Phase-field modeling of magnetic field-induced grain growth in polycrystalline metals

A constitutive model for diffuse interface description of magnetic field-induced grain boundary migration in polycrystalline metals is developed based on the laws of thermodynamics. Within this phase field modeling framework, simultaneous minimization of the total grain boundary energy and the stored magnetic energy within grains provides the driving force for grain growth in a polycrystal material exposure to a magnetic field. Using the available experimental data, phase field simulations of magnetic field induced grain growth in bicrystalline zinc and polycrystalline titanium with two-dimensional columnar microstructure are performed and the model is validated by demonstrating a qualitative and quantitative match with experimental data. Using the validated constitutive model, the effects of magnetic field intensity and direction on evolution of microstructure and polycrystalline texture in titanium are investigated. Quantitative simulation results show that under certain magnetic field directions and sufficient magnetic field intensity, the magnetic energy minimizing driving force can overcome the curvature driving force and cause texture evolution towards less magnetic energy grain orientations during annealing. However, magnetic fields with insufficient intensity or improper direction have negligible effect on grain coarsening by nearly normal grain growth. The desired magnetic field direction and intensity are quantitatively presented for cold-rolled and annealed sheet titanium samples.

The influence of ultrasonic vibration amplitude and magnetic field intensity on microstructural characteristics in laser drilling of Ti6Al4V

Nowadays, laser drilling has found extensive medical applications such as drilling of titanium implants. However, laser drilling of such implants has encountered several restrictions such as low penetration depth, high thickness of recast layer and heat affected zone (HAZ). Therefore, various approaches such as magnetic field and/or ultrasonic vibration aided laser drilling have been proposed to overcome these limitations; among them, few studies have been conducted considering the simultaneous effect of magnetic field and ultrasonic vibrations on microstructural characteristics. Therefore, in the present paper, the effects of magnetic field intensity and ultrasonic vibration amplitude (with a frequency of 28 kHz) have been investigated on the formed phases, thickness of recast layer and thickness of HAZ in laser drilling of Ti6Al4V. According to the obtained results, adding ultrasonic vibrations to the laser drilling process will lead to an average decrease of 29.40% and 28% respectively for the thickness of HAZ and recast layer. However, with the addition of a magnetic field (0.1 Tesla), the thicknesses of HAZ and recast layer were increased by 7% and 11%, respectively. Furthermore, increasing the ultrasonic vibration amplitude was associated with the increase in the acicular alpha phase (α′) as well as more dense, and fine-grained and uniform structure. This can be attributed to the strengthening of convective heat transfer mechanism and higher cooling rate. Additionally, by increasing the intensity of the magnetic field, the structure of the acicular alpha (α′) became finer and the density of lateral branches decreased.

Toward a mechanistic understanding of the magnetic field effect on N-80 carbon steel corrosion in aqueous HCl solution

PurposeThis study aims to describe the effect of magnetic field (MF) on the corrosion rate of N-80 carbon steel [N-80 carbon steel (CS)] in concentrated (12.5 Wt.%, 3.8 M) hydrochloric acid (HCl) using gravimetric weight loss (WL) measurements and potentiodynamic polarization (PDP) in various conditions at ambient temperature.Design/methodology/approachThe effects of MF intensity, magnetization time and elapsed time on corrosion rate (CR) reduction (η) were studied.FindingsThe experimental results show that pre-magnetization of HCl sharply decreases the corrosion rate of N-80 carbon steel (CS) in acid. The maximumηwas found to be 94%. The surface of CS was analyzed with scanning electron microscope in normal and magnetized acid.Originality/valueTo the best of the authors’ knowledge, no studies have delved into the effects of magnetization on the corrosion rate of CS in concentrated HCl solutions. All of the previous research studies deal with an external MF that is applied on the reaction cell, but the magnetization of fluid before coming in contact with CS is investigated for the first time. In the present work, the influence of MF on the corrosion rate of CS in HCl is illustrated using gravimetric WL and PDP methods. The effects of MF intensity as well as period of magnetization and elapsed time were verified in more than 35 tests.

Oriented magneto-conjugate heat transfer and entropy generation in an inclined domain having wavy partition

Energy transmission in an efficient mode has become a crucial challenge in both industrial and biomedical systems because of the worldwide energy crisis. An initiative has been taken by the present research for designing energy-efficient industrial and biomedical systems using different fluids. This numerical study focuses on investigating magneto-hydrodynamic conjugate natural convection and entropy generation of a hybrid nanofluid (Ag-MgO-water) in a differentially heated square domain including heat-generating sinusoidal solid partition. The partition is mid-positioned with a finite thickness and divides the computational regime into two flow domains. The FEM has been applied for solving the governing PDEs. The effects of magnetic field intensity and orientation, cavity inclination, heat generation from the partition and volume fraction of hybrid nanoparticles on temperature distribution, flow field and local entropy generation have been investigated and displayed by isotherms, streamlines and isentropic lines, respectively. The contours have been plotted at the highest Rayleigh number for better visualization of thermo-fluid interaction. Considering a wide variation of free convection, thermal performance is determined through the computation of the average Nusselt number along the hot wall and system energy loss has been evaluated through the calculation of average total entropy generation as well as average Bejan number in both fluid zones. The obtained numerical results show that thermal performance and entropy generation are significantly influenced by the magnetic field intensity and cavity inclination. Thermo-fluid energy transfer is reduced by 11.62% for the highest magnetic field strength whereas the increase of cavity tilting is responsible for a 56.72% decrease in thermal performance. A new regression equation has been derived from the obtained results. The numerical study carried out in this research has superior results compared to the existing methodology and/or experimental/ numerical research.

Magnetic Field Dynamic Strategies for the Improved Control of the Angiogenic Effect of Mesenchymal Stromal Cells.

This work shows the ability to remotely control the paracrine performance of mesenchymal stromal cells (MSCs) in producing an angiogenesis key molecule, vascular endothelial growth factor (VEGF-A), by modulation of an external magnetic field. This work compares for the first time the application of static and dynamic magnetic fields in angiogenesis in vitro model, exploring the effect of magnetic field intensity and dynamic regimes on the VEGF-A secretion potential of MSCs. Tissue scaffolds of gelatin doped with iron oxide nanoparticles (MNPs) were used as a platform for MSC proliferation. Dynamic magnetic field regimes were imposed by cyclic variation of the magnetic field intensity in different frequencies. The effect of the magnetic field intensity on cell behavior showed that higher intensity of 0.45 T was associated with increased cell death and a poor angiogenic effect. It was observed that static and dynamic magnetic stimulation with higher frequencies led to improved angiogenic performance on endothelial cells in comparison with a lower frequency regime. This work showed the possibility to control VEGF-A secretion by MSCs through modulation of the magnetic field, offering attractive perspectives of a non-invasive therapeutic option for several diseases by revascularizing damaged tissues or inhibiting metastasis formation during cancer progression.

The effects of magnetic field intensity on the magnetic properties of Fe80Si9B11 amorphous alloys during magnetic annealing

Magnetic field annealing is an important method to enhance the magnetic properties of amorphous alloys. In this work, the effects of magnetic field annealing intensity on the magnetic properties, mechanical properties, and microstructure of Fe80Si9B11 amorphous ribbons were investigated. It can be seen from the results that the magnetic induction at 1600 A/m (B1600), maximum permeability (μm), coercivity (Hc), Elastic modulus (Er), and Hardness were improved with an increase of the magnetic field intensity. When the magnetic annealing intensity was 2.5 × 10−4 T, the B1600, μm, Hc, Er and Hardness of the sample were improved by 9%, 298%, 67%, 23% and 3%, respectively, compared with those of the as-spun sample. TEM results showed that there are some spherical symmetric clusters present in the 653 K × 2.5 × 10−4 T sample. This may be an important reason for the improvement of the magnetic properties. Compared with the 653 K × 1 T sample, the magnetic field intensity of the 653 K × 2.5 × 10−4 T sample was only 0.025%. However, the values of B1600, μm, Hc, Er and Hardness of the latter reached 96%, 82%, 115%, 90% and 94% of the former, respectively. It means that during the magnetic field annealing process, applying only a small magnetic field can obviously enhance the magnetic and mechanical properties of Fe80Si9B11 amorphous alloy. This provides a theoretical basis for the further improvement of the magnetic and mechanical properties of Fe80Si9B11 alloys, and in the energy saving. The reasons for the changes of magnetic and mechanical properties caused by different magnetic field intensities are discussed.

Effects of intensity of magnetic field generated by neodymium permanent magnet sheets on electrical characteristics of monocrystalline silicon solar cell

<span>In this research, the effects of magnetic field intensity on electrical characteristics of a monocrystalline silicon solar cell were investigated. The experimental test-rig under Standard Test Condition was set up and tested to observe the respective effects. The electrical characteristics in terms of current-voltage-power curves, critical solar cell parameters and fill factor were then examined and analyzed. The outcome of this study demonstrates that the external magnetic field has a positive impact on electrical parameters, the experimental results showed that applying magnetic intensity of 60-260mT significantly affected the electrical characteristics of the cell; i.e., maximized cell current, voltage and power by 12.20, 7.12 and 23.60%, respectively. In addition, this positive impact consequencely happened on the i-v and p-v electrical characteristics curves of the solar cell; reflected by 3.69% increasing in the fill factor. </span>

Study on machining characteristics of magnetically controlled laser induced plasma micro-machining single-crystal silicon

IntroductionLaser induced plasma micro-machining (LIPMM) has proved its superiority in micro-machining of hard and brittle materials due to less thermal defects, smaller heat affected zone and larger aspect ratio compared to conventional laser ablation. ObjectivesIn order to improve characteristics and stability of induced plasma, this paper proposed magnetically controlled LIPMM (MC-LIPMM) to achieve a good performance of processing single-crystal silicon which is widely used in solid state electronics and infrared optical applications. MethodsA comprehensive study on surface integrity and geometrical shape was conducted based on the experimental method. Firstly, the mechanism of MC-LIPMM including laser-plasma, laser-materials interactions and transport effects was theoretically analyzed. Then a series of experiments was conducted to completely investigate the effect of magnetic field intensity, pulse repetition frequency, and bubble behavior on surface integrity and geometrical shape of micro channels. ResultsIt revealed that magnetic field contributed to maximum reduction of 12.64% for heat affected zone and 62.57% for width while maximum increase of 26.23% for depth and 90.26% for aspect ratio. ConclusionThis research confirms that MC-LIPMM can improve the machining characteristics of silicon materials and cavitation bubbles shows an apparently negative impact on the surface morphology.