Effect Of Magnetic Field Configuration Research Articles

A novel industrial magnetically enhanced hydrogen production electrolyzer and effect of magnetic field configuration

Hydrogen energy is a clean, zero‑carbon, flexible and abundant secondary energy. The large-scale deployment of industrial hydrogen production equipment is an effective way to improve renewable energy consumption, the efficiency of hydrogen production from water electrolysis is crucial for equipment deployment. In this paper, a novel industrial magnetically enhanced AWE electrolyzer is designed to improve the efficiency of hydrogen production. The structure and assembly method of the magnetic bipolar plate are introduced, the BOP component is designed and an industrial system-level test platform is built. The results show that the magnetic enhanced electrolyzer can effectively improve the hydrogen production efficiency, however, the effects of different magnetic field configurations (Magnetic field horizontal configuration, MFHC; Magnetic field vertical configuration, MFVC; No magnetic field configuration, NMFC) are significantly different. The magnetic field of MFVC are concentrated inside the bipolar plate and perpendicular to the direction of the electric field, and there is almost no magnetic flux leakage inside the cathode and anode cells. The magnetic field and the electric field of the MFHC configuration are not completely perpendicular, the magnetic field distribution is irregular, there are more magnetic flux leakage in the cells, and the magnetic field intensity is obviously greater than that of the MFVC configuration. Compared with NMFC, MFHC and MFVC significantly improved the hydrogen production efficiency, MFHC performance is better, the current density increased by 28.48% (@50 °C-100 L/h-2 V cell voltage-30%wt KOH), DC power consumption was reduced by 6.2% (CC100A-100 L/h-30%wt KOH). The design method and configuration scheme of magnetically enhanced electrolyzer provide a new idea for the industrial application of magnetic fields in AWE hydrogen production equipment.

Effect of Magnetic Field Configuration on Stray-Crystal Formation with Different Platform Sizes during Directional Solidification of Single-Crystal Superalloy

Effect of Magnetic Field Configuration on Stray-Crystal Formation with Different Platform Sizes during Directional Solidification of Single-Crystal Superalloy

Effects of magnetic field configurations on the minimized ECR ion thrusters for micro-Newton and wide-range operations

Space-based gravitational wave detection missions require precise thrusts over a wide-range of 1–100 μN. In this study, the axial ring-cusp magnetic field configuration is used to design a miniature electron cyclotron resonance ion thruster with a radius of 5 mm. Two typical configurations, i.e., open-type and closed-type, are compared in terms of electron density, electron temperature, and thrust for micro-Newton and wide-range operations. The results show that the open-type achieves high performances owing to the high efficiency of absorption of input microwave power. The lower limit of the mass flow rate in the electron cyclotron resonance (ECR) discharge is expanded to a very low value of 3 × 10−2 sccm to achieve 1 μN in the open-type. The thrust in the open-type could be tuned in a wide-range of 1–119 μN, meeting the requirement.

Particle flux characteristics of a compact high-field cascaded arc plasma device

A new compact cascaded arc device for plasma-wall interaction study is developed at the Institute of Plasma Physics, Chinese Academy of Sciences. A magnetic field up to 0.8 T is achieved to confine plasmas in a 1.2 m long and 0.1 m diameter vacuum chamber. Gas fluid type analysis in this compact vacuum system was done under high particle flux condition. The gas pressure obtained by calculation was consistent with the measurement result. Continuous argon plasma discharge with ion flux of ∼0.5 × 1024 m−2 s−1 is successfully sustained for more than 1 h. The effects of magnetic field configuration, gas flow rate, and discharge arc current on the ion flux to target were studied in detail.

Effects of Magnetic Field Configuration on Ionic Wind Characteristics

Ionic wind has been widely used in the fields of flow control, heat cooling, thruster, and so on. In this work, an investigation of ionic wind under different magnetic field configurations is processed. By changing the position relationship between the electrode and the magnetic field, the magnetic field configuration in the discharge region is modified. With the injection of different magnetic field configurations to the discharge region, the amplitude of Trichel pulse is decreased, and the pulse frequency is increased. Besides, the ionic wind velocities' distribution is deflected and the electrical-to-kinetic energy conversion efficiency is enhanced. The mechanism is analyzed by considering the movement path of particles in the ionization region and drift region under different magnetic field configurations. These results illustrate that the magnetic field configuration would be a method to adjust the direction and improve the electrical-to-kinetic energy conversion efficiency of ionic wind. This method provides a feasible way to regulate the performance of ionic wind without additional energy consumption.

The effect of magnetic field configuration on structural and mechanical properties of TiN coatings deposited by HiPIMS and dcMS

The quality of coatings deposited by magnetron sputtering is known to depend on, among others, the magnetic field strength (Φ) and the magnetic field configuration. Furthermore, high power impulse magnetron sputtering (HiPIMS) is known to result in low defect - high density coatings, and is therefore used to deposit barrier coatings against wear and corrosion. The influence of varying the Φ, on deposition rate (R), structure and hardness of titanium nitride coatings prepared by HiPIMS and dc magnetron sputtering (dcMS) was investigated. At 22mT, the ratio between HiPIMS deposition rate and dcMS deposition rate (RHiPIMS/RdcMS) was almost equal to 1. As Φ was increased from 22mT to 35mT, R decreased by 28% for HiPIMS and increased by 15.6% for dcMS, and RHiPIMS/RdcMS was reduced from 1 to 0.63. From 35mT to 44mT, the decrease in R slowed to 6% for HiPIMS and to 12.5% for dcMS. The (111) orientation was dominant over (200) orientation for both HiPIMS and dcMS, and become less dominant with the Φ in the case of dcMS. The residual stresses and surface roughness were determined and their evolution with Φ is highlighted. Mechanical characterization of the deposited coatings was performed, where the hardness tests showed that on average the HiPIMS coatings (29-34GPa) were some 5 GPa harder than dcMS coatings (25-27GPa).

Magnetic field design for miniature pulse Penning ion source

Magnetic field configuration for a miniature pulse Penning ion source was designed in this work. The amplitude-time characteristics of discharge and extracted currents were investigated as a function of gas pressure for various magnetic field magnitude and configuration An effect of magnetic field configuration on the Penning’s discharge modes and characteristics of the extraction current impulse were experimentally shown. Stable operation modes of the ion source were found in this work. Also the appropriate ranges of working gas pressure and magnetic field configuration were demonstrated, at which the current pulse of the extracted ions had a quasi-rectangular form. For better understanding real magnetic fields distributions of within the discharge cell magnetic field have been calculated in COMSOL software.

Effect of magnetic field configuration on Faraday MHD accelerator

This works aims at the study of a Faraday electric accelerator with the plasma of argon used as the working gas, which is pre-ionized by nuclear energy. The electron density of plasma is above 1020/m3. Different configurations of magnetic field are numerical studied to obtain the influences on the plasma ionization and flowing characteristics. A relatively higher velocity and electron number density are obtained in monotonically decreasing magnetic field generated by magnet with a shorter length. When the plasma flows through the magnetic field generated by 75-mm magnets, the outflow velocity is 2040 m/s, which is higher than 2016 m/s when the plasma flows through the magnetic field generated by 100-mm magnets.

Effect of magnetic field configuration on discharge characteristic of a Hall effect thruster with a variable channel

HET72-VC is a kW-class Hall effect thruster with a variable channel characterized by high thrust and power densities. In this work, an experimental study of the effect of magnetic field configuration on the discharge characteristics of HET72-VC is carried out. By separately adjusting the current through the front and rear coils to change the magnetic field configuration inside the channel, a change in the plume is observed and the discharge performance parameters are measured. Experimental results show that the effects of reducing the front coil current and increasing the rear coil current on the thruster discharge are consistent. The plume gradually changes from a hollow cone with a clear boundary into a solid cone, the thrust increases by about 3%, and the anode efficiency increases by about 2.5%. Theoretical analysis shows that the degree of inclination of the magnetic lines of force plays an important role on the electron conduction and ion acceleration. When the angle between the magnetic lines of force and the channel centerline becomes larger, the discharge performance improves. This study helps in providing a deeper understanding of the working characteristics of this type of thruster, and can provide important guidelines for its structure design and optimization.

Modified dust ion-acoustic surface waves in a semi-bounded magnetized plasma containing the rotating dust grains

The dispersion relation for modified dust ion-acoustic surface waves in the magnetized dusty plasma containing the rotating dust grains is derived, and the effects of magnetic field configuration on the resonant growth rate are investigated. We present the results that the resonant growth rates of the wave would increase with the ratio of ion plasma frequency to cyclotron frequency as well as with the increase of wave number for the case of perpendicular magnetic field configuration when the ion plasma frequency is greater than the dust rotation frequency. For the parallel magnetic field configuration, we find that the instability occurs only for some limited ranges of the wave number and the ratio of ion plasma frequency to cyclotron frequency. The resonant growth rate is found to decrease with the increase of the wave number. The influence of dust rotational frequency on the instability is also discussed.

Effect of magnetic field configuration on the multiply charged ion and plume characteristics in Hall thruster plasmas

Multiply charged ions and plume characteristics in Hall thruster plasmas are investigated with regard to magnetic field configuration. Differences in the plume shape and the fraction of ions with different charge states are demonstrated by the counter-current and co-current magnetic field configurations, respectively. The significantly larger number of multiply charged and higher charge state ions including Xe4+ are observed in the co-current configuration than in the counter-current configuration. The large fraction of multiply charged ions and high ion currents in this experiment may be related to the strong electron confinement, which is due to the strong magnetic mirror effect in the co-current magnetic field configuration.

Effects of magnetic field configuration on the day‐night asymmetry of chorus occurrence rate: A numerical study

AbstractEffects of magnetic field configuration on the day‐night asymmetry of chorus occurrence rate are investigated using a recently developed hybrid code. Previous observational studies show that dayside chorus occurs in regions where the background magnetic field is nearly homogeneous; these observations suggest that the magnetic field configuration might play a significant role in the dayside chorus excitation. In this work, we use a hybrid code to numerically study the threshold conditions of hot electron distributions required to excite chorus waves for different background magnetic field inhomogeneities. Our numerical experiments demonstrate that in a magnetic field with smaller inhomogeneity, smaller temperature anisotropy and smaller number density of hot electrons are needed to excite chorus waves. This conclusion could help explain the higher occurrence rate of chorus waves on the dayside compared with that on the nightside especially in quiet times.

Effect of Magnetic Field Configuration of Dual Magnetron on Carbon Based Films Properties

The article reports on the influence of magnetic field (B field) configuration of dual magnetron on carbon based films properties. The films deposition was performed by means of magnetron sputtering of carbon targets in argon plasma at total pressure range (0.1-1.6 Pa). The carbon films aren’t composed of chemical impurities as measured by Auger electron spectroscopy (AES). The B field configurations affect to a greater extent on mechanical properties and don’t have weighty impact on deposition rates. For «mirror» B field, the films hardness (H) is a higher. The rise of Ar pressure results in a decrease H from 20 to 9 GPa. It is peculiar to a-C and ta-C films. The effect of B field configurations on elastic module (E) is shown in higher pressures.

Effect of magnetic field configuration on parallel plasma flow during neutral beam injection in Heliotron J

The effect of magnetic field configurations on plasma flow velocity was investigated by measuring the parallel flow velocity (v∥) using a charge-exchange recombination spectroscopy during neutral beam injection in three different toroidal mirror configurations of Heliotron J: high, standard and reversed mirror configurations. The magnetic ripple strengths, γ, for these mirror configurations were γ = 0.073 m−1, 0.031 m−1 and 0.027 m−1, respectively, at the normalized averaged minor radius ρ = 0.07. The magnetic ripple strength is defined as γ = {〈(∂B/∂l)2/B2〉}1/2, where 〈…〉 is the flux surface averaged value and l is the length along the magnetic field line. At ρ = 0.07, the parallel flow velocity in the high mirror configuration (v∥ ∼ 4 km s−1) was 2–3 times smaller than those in the standard and reversed mirror configurations (v∥ ∼ 10–12 km s−1). An anticipated interpretation is that the difference in the neoclassical damping force contributes to the difference in v∥ among the three mirror configurations.

Simulation study on hydrogen penning source discharge at low pressure

In order to better comprehend the dynamic behaviours of ion and electron during the Penning source discharge process under a low pressure and weak ionization condition, numerical simulation is carried out to study the penning source discharge and diffuse process. For constituting 2D axial symmetrical model and combining the particle simulation and Monte Carlo (PIC/MCC) method, elastic collision, excitation, and ionization reactions between electrons and hydrogen molecules, hydrogen atom and ions are taken into account. The effect of magnetic field configuration, secondary electron emission coefficient, derivational voltage, and gas pressure on the discharge characteristics is investigated. It has been found that the simulant discharge parameters, including electron and ion densities, anodic current and ionic current, H+ and H2+ densities, etc, are in good agreement with the experimental results. Based on our numerical simulation, the study of the hydrogen penning discharge is being changed from qualitative analysis to quantitative calculation, which is important for the design and optimization of the penning ion source.

The effect of magnetic field configuration and propellant supply rate on insulator erosion in a hall thruster

Dependence of the rate of insulator erosion on the walls of discharge chamber of a Hall thruster on the propellant supply rate and magnetic field configuration at a constant discharge voltage has been studied. The regime of thruster operation was controlled by varying the propellant mass flow rate. The magnetic field configuration was optimized by monitoring the intensity of the spectral line of sputtered boron atoms. It is established that the rate of insulator erosion in the discharge chamber significantly decreases upon optimization of the magnetic field configuration, while the integral characteristics of the thruster change rather insignificantly. With the optimum magnetic field configuration, the rate of erosion of discharge chamber walls depends rather insignificantly on the propellant supply rate.

Experimental Study on the Effects of Magnetic Field Configuration near the Channel Exit on the Plume Divergence of Hall Thrusters

Experimental investigations into the effects of the magnetic field configuration near the channel exit on the plume of Hall thrusters were conducted. The magnetic field configuration near the channel exit is characterized by the inclination angle between the magnetic field lines and the thruster radial direction. Different inclination angles were obtained by varying the current ratio in the coils. The plume divergence angles were measured by a dual-directed probe. The results showed that the plume divergence angle increased obviously with the increase in the magnitude of the inclination angle near the channel exit. Therefore, in order to optimize the magnetic field for reducing plume divergence, the magnitude of the inclination angle should be reduced as much as possible. It suggests that the magnetic field configuration near the channel exit is another important factor that affects plume divergence.

Comparative study of niobium nitride coatings deposited by unbalanced and balanced magnetron sputtering

Niobium nitride (NbN) coatings have many interesting properties such as chemical inertness, excellent mechanical properties, high electrical conductivity, high melting point, and a superconducting transition temperature between 16 and 17 K. For this reason, these compounds have many potential thin film applications. In this work we compare the properties of NbN x films deposited using well-characterized balanced and unbalanced magnetron sputtering systems. Samples of NbN were deposited in the two systems under almost identical deposition conditions, that is, the same substrate temperature, plasma power, gas pressure, substrate to target distance and Ar/N 2 ratio. Prior to the film preparation both the magnetic field geometry and the characteristics of the plasma were determined. The microstructure and composition of the deposits were analyzed by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. The corrosion resistance and the micro-abrasion wear resistance were measured by anodic polarization potentiodynamic studies and by ball cratering, respectively. The NbN films grown using the highly unbalanced magnetron configuration had a preferential (111) crystal orientation and a composite hardness of up to 2400 HV 0.025. While the films deposited using the balanced magnetron had a mixed crystalline orientation and a hardness of 2000 HV 0.025. The results demonstrate the strong effect of magnetic field configuration on the ion bombardment, and the resultant coating characteristics.

Study of magnetic configuration effects on plasma boundary and measurement of edge electron density in the spherical tokamak compact plasma wall interaction experimental device using Li sheet beam

Two-dimensional lithium beam imaging technique has been applied in the spherical tokamak CPD (compact plasma wall interaction experimental device) to study the effects of magnetic field configurations on rf plasma boundary in the absence of any plasma current, and also for the measurement of a two-dimensional edge electron density profile. With the present working condition of the diagnostics, the minimum measured electron density can be ∼1.0×1016m−3; this is considered to be the definition for the plasma boundary. The performance of the lithium sheet beam is absolutely calibrated using a quartz crystal monitor. Experimental results reveal that magnetic field configuration, either mirror or so-called null, critically affects the rf plasma boundary. A sharp lower boundary is found to exist in magnetic null configuration, which is quite different from that in the weak mirror configuration. Theoretical calculations of particle drift orbit and magnetic connection length (wall-to-wall) suggest that only mirror trapped particles are confined within a region where the magnetic connection length is ∼4.0m or more. A two-dimensional edge electron density profile is obtained from the observed LiI intensity profile. Overdense plasma formation is discussed from the viewpoint of mode conversion of rf wave into electron Bernstein wave and its dependence on the electron density profile.

Effects of magnetic field configuration on thrust performance in a miniature microwave discharge ion thruster

The effects of magnetic field configuration on thrust performance in a miniature microwave discharge ion thruster were investigated in order to improve thrust performance. First, the extracted ion beam current was measured for various levels of strength of the magnetic field. It was found that there is an optimum magnitude of the magnetic field. That this is due to the tradeoff between magnetic mirror confinement and microwave-plasma coupling was confirmed by measurement of the ion saturation current into the antenna of the ion thruster. The ion saturation current was found to decrease with an increase in magnetic field strength, due to the improvement in magnetic mirror confinement. The estimated electron temperature also decreases with an increase in magnetic field strength. This result shows that the increase in magnetic field strength leads to a decrease in microwave-plasma coupling. Next, the ion beam current for three magnetic field shapes was measured by changing the length of the central yoke. The results show that the optimum magnetic field shape depends on the mass flow rate because of the tradeoff between magnetic confinement and ionization probability. For the configurations tested, the 3 mm length central yoke is optimal for low mass flow, whereas 7 mm is the best for high mass flow. Overall, the extracted ion beam current is 21.4 mA, at a xenon mass flow rate of 0.036 mg/s, beam voltage of 1500 V, and incident microwave power of 16 W.