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Holographic interferometric microscopy for measuring Cu2+ concentration profile during Cu electrodeposition in a magnetic field
摘要： We measured the concentration boundary layer during copper electrodeposition in a copper sulfate solution under an applied magnetic field. Using a holographic laser interference microscope, we demonstrated the formation of the diffusion layer near the cathode. In the initial stage of electrodeposition, the diffusion layer was distorted in a magnetic field. An analysis of the electrode surface concentration supported the following assertions: without a magnetic field, dendrites formed when the surface concentration of Cu2+ was depleted; with a magnetic field, the unique convection phenomena of the field gradient force and localized Lorentz force promoted Cu2+ mass transport in the diffusion layer, producing large crystal grains.
关键词： Diffusion layer,Magnetohydrodynamic,Magnetic field,Localized Lorentz force,Field gradient force
更新于2025-09-04 15:30:14
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Modification of GaN thin film on sapphire substrate optical properties under weak magnetic fields
摘要： We present a study of the modifications to the optical transmittance of GaN thin film on sapphire substrate due to weak magnetic field (WMF) treatment. Measurements were performed in the 320-1100 nm wavelength range at 300 K, evidencing a change in transmission spectra for wavelengths above 700-800 nm after the WMF treatment. We use a model with three layers to simulate transmittance spectra. We have found that changes of the optical thickness induced by WMF are not sufficient to explain discrepancies between experimental and simulated spectra. To obtain a complete agreement it is necessary to consider a change in the refractive index of GaN and/or in the reflection coefficients for the interface air-GaN. We interpret such WMF-related effects as due to the diffusion of point defects after dissolution of metastable complexes from inner boundaries to surface of the structure. These defects modify optical properties of the GaN film.
关键词： reflectance,transmittance,weak magnetic field,gallium nitride
更新于2025-09-04 15:30:14
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POLARIZATION TRANSFORMATION BY A HYPERBOLIC METAMATERIAL ON A METAL SUBSTRATE
摘要： In the present paper we focus on the study of polarization properties of biaxial metamaterial, which consist of alternate ferrite and semiconductor layers, located on an ideally conducted metal substrate. The system is placed into an external magnetic field along the boundaries of the layers. The effective medium theory is applied. Effective linear-to-elliptic polarization conversion has been shown, by means of physical and geometrical parameters of the system under consideration.
关键词： biaxial metamaterial,ferrite,linear-to-elliptic polarization conversion,metal substrate,polarization properties,semiconductor layers,external magnetic field,effective medium theory
更新于2025-09-04 15:30:14
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Tunneling ionization of atoms and ions in a linear electromagnetic wave and a constant magnetic field and the “imaginary time” method
摘要： The tunneling ionization of atoms and negative ions in an intense linearly polarized laser ?eld and a constant uniform magnetic ?eld is discussed in the quasiclassical theory framework. We use the “imaginary time” method, where tunneling is described by the classical equations of motion but with purely imaginary “time” to derive the extremal subbarrier trajectory of the photoelectron. This allows to obtain simple analytical expressions for ionization rates in the tunneling regime for an arbitrary angle between a laser beam and a constant magnetic ?eld accounting for the Coulomb interaction of the photoelectron with the atomic core. The resonance case, when the frequency of a monochromatic electromagnetic wave and the cyclotron frequency are equal, is also considered. The limits of weak and strong magnetic ?elds and the expressions for the barrier width and the emission angle of photoelectrons are discussed. It is shown that a magnetic ?eld in the presence of a linear electromagnetic wave increases the barrier width and thus decreases the ionization probability, i.e., stabilizes the bound level.
关键词： linear electromagnetic wave,imaginary time method,atoms,ions,quasiclassical theory,tunneling ionization,constant magnetic field
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Mitigating Internal Resonances of the Magnetic-Field Integral Equation via Double-Layer Modeling
摘要： We present a new method to mitigate internal resonances of the magnetic-field integral equation (MFIE) for closed conductors, without combining this equation with the electric-field integral equation (EFIE) that is commonly practiced in the literature. For a given object and its surface, a smaller closed surface is placed inside to create a double layer. This way, the magnetic field intensity is enforced to zero on the inner surface, making the overall solution unique at all frequencies. By eliminating the need for EFIE, the resulting implementation is purely based on MFIE interactions. In addition to its formulation, the initial numerical results of the proposed method on canonical problems are presented.
关键词： internal resonance problem,magnetic-field integral equation,surface integral equations,Boundary element methods
更新于2025-09-04 15:30:14
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Campo Magnético em Super-Redes Semicondutoras de Cristais
摘要： In this work we present a study on the super-semiconductor networks, using the Kronig-Penney model for the effective mass approximation, and then the calculations for the application of the magnetic field perpendicular and parallel to the layers of super lattices crystals. The magnetic field applied parallel to the layers, was used to adjust the resonance of a higher energy subband of a well by thermal excitation with a lower energy subband of the adjacent well, increasing energy levels in its tunneling rate. We use the formalism of Schr?dinger equation of quantum mechanics. Introducing the calculations in a systematic way in superlattices for each semiconductor quantum well to assess their energy spectrum systematically studied.
关键词： Kronig-Penney Model,Magnetic Field,Superlattices Semiconductors
更新于2025-09-04 15:30:14
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Valley Subband Splitting in Bilayer Graphene Quantum Point Contacts
摘要： We report a study of one-dimensional subband splitting in a bilayer graphene quantum point contact in which quantized conductance in steps of 4e2=h is clearly defined down to the lowest subband. While our source-drain bias spectroscopy measurements reveal an unconventional confinement, we observe a full lifting of the valley degeneracy at high magnetic fields perpendicular to the bilayer graphene plane for the first two lowest subbands where confinement and Coulomb interactions are the strongest and a peculiar merging or mixing of K and K0 valleys from two nonadjacent subbands with indices eN; N t 2T, which are well described by our semiphenomenological model.
关键词： conductance quantization,magnetic field,quantum point contact,valley degeneracy,bilayer graphene
更新于2025-09-04 15:30:14
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Electromagnetic Wave Theory for Calculation of Exact Magnetic Field in Case of BWO
摘要： Overall efficiency of high power microwave generating device depends upon input current in the form of electron beam and currents required for electromagnets. In order to increase the efficiency of device, if electromagnets are replaced by permanent magnets, overall efficiency of device shall increase. So, calculation of exact magnetic field is required. In this paper, the exact relation of magnetic field required in high power microwave generation using Backward Wave Oscillator (BWO) is found. BWO interacts with slow waves and is the most promising device to produce high power microwaves. The interaction involves the beams from high current density and the waveguide mode. An exact relation that specifically relates the various parameters of the waveguide like slow wave structures (SWS) dimensions, input beam voltage and operational frequency with axial magnetic field is derived. The derived equation gives calculation of exact values of magnetic field for focusing of beams. Theoretical and simulated work show good agreement with the previously available experimental data. So, with the derived electromagnetic wave relation exact value of magnetic field is calculated for desired frequency and power regime.
关键词： High current electron,High power microwave,Wiggler,Magnetic field,Oscillator
更新于2025-09-04 15:30:14
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The Double Slit Experiment-Explained
摘要： The wavelet envisioned by Huygen’s in diffraction phenomenon is re-interpreted as being polarized after passing through slit/hole which removed the electric field component from the Electromagnetic Radiation (EM-R), the remained wave consist of the Circular Magnetic Field (CMF), this CMF lost the speed of light and the electric field, hence it’s a short distance travel field, originated from the CMF produced by accelerated electrons, integrated with the Electric Field (EF) during the Flip-Flop (F-F) mechanism producing EM-R; hence the passing of light through a single hole/slit resulted in a CMF which reproduced as rings on the monitor screen in single wave diffraction, while the interference of two such CMF in double slits experiment, produced constructive or destructive interference forming patches on the monitor screen; and the perceived electron diffraction is an enter of two CMF from a single electron into a slit then emerged to produce constructive or destructive interference, in addition to the electron which entered and emerged from the slit with the stronger CMF, the paper finally derived the origin of Planck ‘constant (h) for the second time; the logical interpretation of double slits diffraction will restore the common sense in the physical world, distorted by the pilot wave.
关键词： Electron diffraction,wavelet,Circular magnetic field,Double slit experiment,Polarization,Origin of Planck’ constant
更新于2025-09-04 15:30:14