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Magnetic field to focalize and accelerate ions produced by ns laser-generated plasmas
摘要： Solid targets have been irradiated in vacuum by an ns-laser pulse producing non-equilibrium plasma accelerating ions along the normal to the target surface. The ions emission can be focused by cylindrical permanent magnets in order to enhance the ion current. The electron traps formation along the main emission direction produces an electrical field driving further ion acceleration. Measurements using time-of-flight technique have been developed to quantize the focusing and accelerating effects induced by the applied magnetic field. Experimental measurements were compared with theoretical calculations obtained using COMSOL software, as it will be presented and discussed.
关键词： ion acceleration,time-of-flight technique,Magnetic field,laser-generated plasmas,COMSOL software
更新于2025-09-16 10:30:52
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Magnetically controlled exciton transfer in hybrid quantum-dot–quantum-well nanostructures
摘要： A magnetophotoluminescence study of the carrier transfer with hybrid InAs/GaAs-quantum-dot–InGaAs-quantum-well structures is carried out where we observe an unusual dependence of the photoluminescence (PL) on the GaAs barrier thickness at strong magnetic ?eld and excitation density. For the case of a thin barrier the quantum-well (QW) PL intensity is observed to increase at the expense of a decrease in the quantum-dot (QD) PL intensity. This is attributed to changes in the interplane carrier dynamics in the QW and the wetting layer (WL) resulting from increasing the magnetic ?eld along with changes in the coupling between QD excited states and exciton states in the QW and the WL.
关键词： quantum-dot,magnetic field,magnetophotoluminescence,quantum-well,carrier transfer
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Vector magnetic field sensor based on polarization-maintaining fiber long-period grating with magnetic fluid
摘要： We present a vector magnetic field sensor based on long-period thin-cladding polarization-maintaining fiber and immersed the grating in magnetic fluid. The proposed sensor can measure both magnetic intensity and orientation simultaneously.
关键词： birefringence,long-period grating,magnetic field,polarization-maintaining fiber
更新于2025-09-16 10:30:52
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Magnetic field induced vortices in graphene quantum dots
摘要： The energy spectrum and local current patterns in graphene quantum dots are investigated for different geometries in the presence of an external perpendicular magnetic field. Our results demonstrate that, for specific geometries and edge configurations, the quantum dot exhibits vortex and anti-vortex patterns in the local current density, in close analogy to the vortex patterns observed in the probability density current of semiconductor quantum dots, as well as in the order parameter of mesoscopic superconductors.
关键词： graphene quantum dots,magnetic field,energy spectrum,local current patterns,vortices
更新于2025-09-16 10:30:52
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Three-dimensional measurements of plasma parameters in an inductively coupled plasma processing chamber
摘要： Inductively coupled plasmas (ICPs) are extensively used for materials processing and microelectronics fabrication. However, their electromagnetic properties have not been fully characterized. In this regard, we have performed fully three dimensional (3D), time dependent measurements of the magnetic ?eld, electron density, and electron temperature for an ICP sustained in argon in an industrial reactor designed for plasma etching in microelectronics fabrication. These measurements were compared to modeling results. The plasma was generated using pulsed power delivered at 2 MHz by a planar coil. The magnetic ?eld was measured using a three axis magnetic probe at 15 366 locations throughout the plasma volume during the H-mode portion of the pulse at temporal intervals of 2 ns. A swept Langmuir probe was used to measure plasma parameters at the same locations. The plasma density measurement was calibrated with line-integrated densities obtained using a 96 GHz interferometer. During a single radio frequency (RF) cycle, the 3D current density [derived from Be~r; tT]is initially maximum just below the coil and moves downward toward the center of the chamber. Isosurfaces of current are nearly symmetric toroids. The total electric ?eld, space charge ?eld, and inductive electric ?eld were derived and used to calculate the dissipated power, plasma current, and Poynting ?ux. Computer modeling of the experiment reproduces the phase dependent behavior. Animations showing the time dependent 3D measurements are presented in the supplementary material.
关键词： plasma etching,electron density,magnetic field,electron temperature,microelectronics fabrication,Inductively coupled plasmas
更新于2025-09-16 10:30:52
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Theory for polaritons in graphene photonic crystals in an applied magnetic field
摘要： The dispersion relations for bulk and surface plasmon-polaritons in a semi-infinite 1D photonic crystal interlayered with graphene are calculated in the presence of an applied magnetic field. The results are applied to SiO2 as the constituent material in a geometry where the layers are arranged in a periodic array with the same layer thickness. The static magnetic field is applied perpendicular to the plane of layers. Numerical results are presented for the modes in THz range, up to 10 THz, to illustrate the important role of the applied magnetic field on the graphene sheets in modifying the polariton dispersion curves, especially for magnetic fields of the order of 1 T. It is found that the polariton frequencies and band gaps have a sensitive dependence on the electron scattering rate parameter (and hence the applied magnetic field strength) in the graphene sheets. Electromagnetic retardation effects are fully taken into account for the bulk bands, while for the surface modes (which are shown to have a novel non-reciprocal propagation characteristics) it is convenient to focus on the regime where retardation is small.
关键词： Magnetic field effects,Photonic crystals,Graphene,Transfer-matrix methods,Plasmon-polaritons
更新于2025-09-16 10:30:52
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[IEEE 2019 Thirteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Rome, Italy (2019.9.16-2019.9.21)] 2019 Thirteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Highly sensitive magnetometry method based on the magnetoplasmonic crystal
摘要： A novel concept of the room-temperature magnetoplasmonic magnetic field sensor with high sensitivity and spatial resolution is presented. The advanced flux-gate technique is used. Magnetization of the fully saturated magnetic film is rotated in the film plane and the monitored magnetic field is measured by detecting variation of optical transmittance through the sensing element. The sensing element is a magnetoplasmonic crystal consisting of a gold grating with subwavelength period deposited on a thin transparent dielectric film of bismuth substituted iron-garnet. Geometrical parameters of the magnetoplasmonic crystals are adjusted to have pronounced resonances of the longitudinal magneto-photonic intensity effect (LMPIE). The experimental study revealed that such approach allows one to reach the 2nT sensitivity level which was limited by the noise of the laser. The demonstrated magnetoplasmonic magnetometry method is promising for mapping and visualization of ultra-small magnetic fields.
关键词： magnetic field sensor,magnetometry,LMPIE,magnetoplasmonic crystal
更新于2025-09-16 10:30:52
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[IEEE 2019 5th International Conference on Electric Power Equipment - Switching Technology (ICEPE-ST) - Kitakyushu, Japan (2019.10.13-2019.10.16)] 2019 5th International Conference on Electric Power Equipment - Switching Technology (ICEPE-ST) - Two-Dimensional Observation of Single Cathode Spot Copper Vapor in Vacuum Arcs by Laser-Induced Fluorescence
摘要： Vacuum arc cathode spots are centers of metal vapor evaporation, electron emission and plasma production. Arc properties are dominated by the behavior of the cathode spots. A systematic investigation on the density of copper metal vapor emitted from a single cathode spot is benefit for understanding the mechanism of vacuum arc discharge. The objective of this paper is to get the spatial density distribution of copper neutral atoms emitted from a single cathode spot in ~55A vacuum arc by planar Laser Induced Fluorescence (LIF) method. The experiments are conducted with CuCr10 (Cr weight of 10%) butt contacts in a demountable vacuum chamber. 2D distribution of copper metal vapor density is photographed by an intensified CCD cameral (i-CCD) with an exposure time of 50 ns. The uniform constant Axial Magnetic Field (AMF) within the inter-contacts region is supplied by Helmholtz coils. 2D copper vapor density distribution between two electrodes as well as the influence of external AMF on vapor density distribution are investigated. When the arc current is ~55 A, a typical cathode spot or two spots are observed in the experiments. Copper vapor density reaches the maximum value 6×1019 m-3 in the center of cathode spot.
关键词： Vacuum arc,Laser Induced Fluorescence,copper vapor density,cathode spots,Axial Magnetic Field
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Comparison of magnetic field imaging (MFI) and magnetic field simulation of silicon solar cells
摘要： In solar cells, electric currents are generated by electric injection or light flow distributed over the whole area. Each flowing current generates a magnetic field depending on the strength and the direction of the electric current. Recently, a new measuring technology, called magnetic field imaging (MFI) was presented showing the potential to measure the electric current strength and direction by imaging the resulting magnetic fields. The method was applied to various defects, e.g. missing or defect solder point between solar cell interconnector and cross-connector. Here, MFI measurements of various solar cell configurations and solar cell defects are compared with a finite elemental magnetic field simulation. The results are qualitatively and quantitatively interpreted and discussed. The model is used to obtain limits in resolution depending on measuring height and measurable defects (connector brakeage or defect soldering point) of the MFI method. The variation of geometry and material parameters (within reasonable boundaries) on the current flow and the corresponding magnetic field distribution show negligible influence of manufacturing tolerances regarding layer thicknesses and ribbon/connector width as well as material fluctuations resulting in variation of electrical resistance. Measuring height and electrical current have the biggest influence on magnetic field strength and are therefore starting points for process and product optimization.
关键词： magnetic field imaging,FEM,finite element method,MFI,solar cell defects,silicon solar cells
更新于2025-09-16 10:30:52
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Wavelength and Constant Magnetic field Dependence of the Steady-state Photoconductivity of a Bifacial Silicon Solar Cell
摘要： In this work, a theoretical study on the photoconductivity of a bifacial silicon solar cell under monochromatic illumination and constant magnetic field is presented. Analytical expression of the photoconductivity is established according to base depth, illumination wavelength, junction recombination velocity and magnetic field value. The photoconductivity profile versus wavelength shows two energy absorption peaks corresponding to specific wavelengths. Based on a linear model of the photoconductivity versus junction recombination velocity, in a given interval, we determine an equivalent capacitance which depends on both wavelength and magnetic field.
关键词： Capacitance,Recombination velocity,Wavelength,Photoconductivity,Magnetic field
更新于2025-09-16 10:30:52