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Modeling and Numerical Simulation of Material Science 2014年第3期4卷 136-142页

作者： Abel Garcia-Barrientos volodymyr grimalsky CIICAp Autonomous University of Morelos State (UAEM) Morelos México Electronics and Computer Science Department Research Center on Information Technology and Systems Autonomous University of Hidalgo State (UAEH) Hidalgo México

Numerical simulations of nonlinear interaction of space charge waves in microwave and millimeter wave range in n-InN films have been carried out. A micro- and millimeter-waves frequency conversion using the negative differential conductivity phenomenon is carried out when the harmonics of the input signal are generated. An increment in the amplification is observed in n-InN films at essentially at high-frequencies f < 450 GHz, when compared with n-GaAs films f < 44 GHz. This work provides a way to achieve a frequency conversion and amplification of micro- and millimeter-waves.

关键词： Space Charge Waves InN Film Negative Differential Conductivity

Collapse of Nonlinear Dust Sound Pulses in Cylindrical Dusty Plasma Waveguides

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Journal of Electromagnetic Analysis and Applications 2015年第3期7卷 89-95页

作者： volodymyr grimalsky Svetlana Koshevaya Anatoliy Kotsarenko Alvaro Zamudio-Lara CIICAp Autonomous University of State Morelos (UAEM) Cuernavaca Mexico Faculty of Engineering Autonomous University of Carmen (UNACAR) Ciudad Del Carmen Mexico

Nonlinear monopulses of dust sound waves in cylindrical dusty plasma waveguides bounded by a dielectric are investigated. The dusty plasma includes the positive ions as a light component and the negative dust as a heavy one. The dusty plasma with different masses of dust particles is considered. The set of hydrodynamic equations for the dust jointly with the Poisson one are used. The Boltzmann distribution is valid for the ions. The boundary conditions are applied at the smooth interface. When the moderate volume nonlinearity manifests, near the interface the variations of the dust concentration reach extremely high values, and the collapse of the dust sound waves occurs. In the cylindrical waveguides the collapse manifests at the values of the initial wave amplitudes essentially smaller than in the planar geometry. When the particles of lower masses are near the interface, the collapse realizes more rapidly.

关键词： Dusty Plasma Cylindrical Waveguide Different Masses Wave Collapse

Nonlinear Terahertz Electromagnetic Waves in SrTiO₃ Crystals under Focusing

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Journal of Electromagnetic Analysis and Applications 2016年第10期8卷 226-239页

作者： volodymyr grimalsky Svetlana Koshevaya Jesus Escobedo-Alatorre Margarita Tecpoyotl-Torres CIICAp Autonomous University of State Morelos (UAEM) Cuernavaca Mexico

The nonlinear waves of terahertz (THz) range are investigated in the paraelectric crystals SrTiO3 at the temperatures ~77 K. The frequency dispersion is important there. In the absence of a bias electric field the dominating nonlinearity is cubic. The frequency dispersion and nonlinearity correspond to existence of envelope solitons and the modulation instability (MI) of long input pulses, whereas in the transverse direction MI is absent. There exists a possibility to generate the regular sequences of short THz pulses due to MI in bounded SrTiO3 crystals. The focusing of input long pulses reduces the threshold of MI, increases the output amplitudes of the short pulses, and provides more stable generation of the short pulses. It is investigated the frequency multiplication of THz electromagnetic radiation in bounded paraelectric SrTiO3 when a bias electric field is applied. The dominating nonlinearity is quadratic there. The frequency dispersion and the transverse width of the input wave beams affect the generation of higher harmonics. It is possible to select the certain numbers of higher harmonics by means of the optimum length of the crystal, by the width of the beam of the input first harmonic, and by the focusing of the input first harmonic.

关键词： THz Waves SrTiO3 Paraelectric Nonlinearity Frequency Dispersion Focusing Modulation Instability Generation of Harmonics

Simulations of the Electron Spectrum of Quantum Wires in <i>n</i>-Si of Arbitrarily Doping Profile by Thomas-Fermi Method

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Journal of Electromagnetic Analysis and Applications 2018年第8期10卷 143-156页

作者： volodymyr grimalsky Svetlana Koshevaya Jesus Escobedo-Alatorre Igor Moroz CIICAp IICBA Autonomous University of State Morelos (UAEM) Cuernavaca Mexico Faculty of Mathematics and Informatics Rivne State Humanitarian University Rivne Ukraine

Electron spectrum in doped n-Si quantum wires is calculated by the Thomas-Fermi (TF) method under finite temperatures. The many-body exchange corrections are taken into account. The doping profile is arbitrary. At the first stage, the electron potential energy is calculated from a simple two-dimensional equation. The effective iteration scheme is proposed there that is valid for multidimensional problems. Then the energy levels and wave functions of this quantum well are simulated from the Schrödinger equations. The expansion by the full set of eigenfunctions of the linear harmonic oscillator is used. The quantum mechanical perturbation theory can be utilized to compute the energy levels. Generally, the perturbation theory for degenerate energy levels should be used.

关键词： Cylindrical Quantum Well High Arbitrary Doping Thomas-Fermi Method Electron Spectrum Possible Degeneration of Levels

Different Geometries of Superheterodyne Amplification of Electromagnetic Beams in Waveguides Nitride-Dielectric

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Journal of Electromagnetic Analysis and Applications 2020年第11期12卷 159-168页

作者： Jesus Escobedo-Alatorre volodymyr grimalsky Svetlana Koshevaya Margarita Tecpoyotl-Torres Institute for Basic and Applied Research (IICBA) Center for Investigations on Engineering and Applied Science (CIICAp) Autonomous University of State Morelos (UAEM) Cuernavaca Mexico

The superheterodyne amplification of electromagnetic waves is investigated when the resonant three-wave interaction of two electromagnetic waves with the space charge wave occurs in the waveguides nitride n-GaN, n-InN films-dielectric. The amplification of SCW waves due to the negative differential conductivity is investigated in nitride n-GaN, n-InN films at the frequencies f ≤ 400 GHz in the lower part of the terahertz (THz) range. The electromagnetic waves are either in the upper part of THz range or in the optical range. The superheterodyne amplification is considered in two geometries, the collinear one in which the three interacting waves travel in the same direction and the anti-collinear geometry where the second electromagnetic wave propagates in the opposite direction. The preferences and drawbacks of each geometry are pointed out. The finite width of space charge waves leads to decrease of increments of amplification.

关键词： Superheterodyne Amplification Negative Differential Conductivity Space Charge Wave Nitride Films Terahertz Range

Influence of Nonlocality on Amplification of Space Charge Waves in n-GaN Films

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Journal of Electromagnetic Analysis and Applications 2011年第2期3卷 33-38页

作者： volodymyr grimalsky Svetlana Koshevaya Margarita Tecpoyotl-T. Fernanda Diaz-A. 不详

It is investigated theoretically the amplification of space charge waves (SCWs) due to the negative differential conduc-tivity (NDC) in n-GaN films of submicron thicknesses placed onto a semi-infinite substrate. The influence of the nonlo-cal dependence of the average electron velocity on the electron energy is considered. The simplest nonlocal model is used where the total electron concentration is taken into account. The relaxation momentum and energy frequencies have been calculated. The influence of the nonlocality on NDC results in the decrease of the absolute value of its real part and appearance of the imaginary part. The calculation of the diffusion coefficient leads to essential errors. The simulations of spatial increments of the amplification of SCWs demonstrate that the nonlocality is essential at the fre-quencies f ? 150 GHz, and the amplification is possible up till the frequencies f ? 400 ??? 500 GHz.

关键词： Gallium Nitride Films Negative Differential Conductivity Space Charge Waves Amplification Nonlocality

Generation of Higher Terahertz Harmonics in Nonlinear Paraelectrics under Focusing in a Wide Temperature Range

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Journal of Electromagnetic Analysis and Applications 2023年第4期15卷 43-58页

作者： volodymyr grimalsky Jesus Escobedo-Alatorre Christian Castrejon-Martinez Yered Gomez-Badillo Center for Investigations on Engineering and Applied Science (CIICAp) Institute for Investigations on Basic and Applied Science (IICBA) Autonomous University of State Morelos (UAEM) Cuernavaca Mor. Mexico Tecnológico Nacional de México/Instituto Tecnológico de Zacatepec Zacatepec Mor. Mexico

It is theoretically investigated the generation of higher harmonics of two-dimensional and three-dimensional terahertz electromagnetic beams in nonlinear crystals. The attention is paid to crystalline paraelectrics like SrTiO3 under the temperatures 60 - 200 K, these crystals possess the cubic nonlinearity. The bias electric field is applied to provide the dominating quadratic nonlinearity. The initial focusing of the beams not only increases the efficiency of generation of higher harmonics, but alto makes possible to select maxima of different higher harmonics at some distances from the input. At lower temperatures the nonlinearity behaves at smaller input amplitudes, whereas at higher temperatures the harmonic generation can be observed at higher frequencies up to 1.5 THz. In three-dimensional beams the peak amplitudes of higher harmonics can be bigger than in two-dimensional beams, but the ratios of these peak values to the maximum values of the focused first harmonic are smaller than in two-dimensional beams.

关键词： Terahertz Wave Beams Nonlinear Crystalline Paraelectrics Different Temperatures Generation of Harmonics Initial Focusing

Simulation of Modes of Ionosphere Alfven Resonator with High Quality Factors in the Case of Oblique Geomagnetic Field

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Journal of Electromagnetic Analysis and Applications 2012年第5期4卷 192-198页

作者： volodymyr grimalsky Svetlana Koshevaya Anatoliy Kotsarenko Marco A. Cruz Chavez Autonomous University of State Morelos (UAEM) CIICAp Morelos Mexico Center of Geoscience UNAM is Autonomous National University of Mexico (UNAM) Queretaro Mexico

The properties of the ionosphere Alfvén resonator (IAR) in the general case of an oblique geomagnetic field are investigated. The modes at the frequencies f = 0.2 - 10 Hz well localized within the ionosphere are considered, which are important for the lithosphere—ionosphere coupling. An attention is paid to the modes with quite high quality factors , where . A proper selection of calculated eigenfrequencies has been realized. Two independent simulation algorithms have been proposed. The resonant frequencies and the profiles of magnetic field components of the modes have been calculated. The modulation of electron and ion concentrations at the heights 170 - 230 km leads to essential shifting the resonant frequencies.

关键词： Alfvén Resonator Resonant Modes Quality Factors Modulation

Detailed Study of Radon Spatial Anomaly in Tlamacas Mountain Area, Volcano Popocatepetl, Mexico

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Open Journal of Geology 2016年第3期6卷 158-164页

作者： Anatolyi Kotsarenko Vsevolod Yutsis Vladimir grimalsky Svetlana Koshevaya Facultad de Ingeniería Universidad Autónoma del Carmen Cd. del Carmen México División de Geociencias Aplicadas Instituto Potosino de Investigación Científica y Tecnológica San Luis Potosí Mexico Centro de Investigación en Ingeniería y Ciencias Aplicadas Universidad Autónoma del Estado de Morelos Cuernavaca México

Results of a soil radon survey accomplished by 2 different methods during 2 different periods in the area of Tlamacas Mountain are presented. The first study, carried out from 15-APR-2010 to 09-MAY-2010 in 30 measurement sites by means of CR39 solid state nuclear detectors, shows 2 active zones with intensive radon emanation with a characteristic dimension of about 300 meters located in the northwestern and western parts of the Mountain. The second survey, made on 05-JUL-2011 in 23 measurement sites with 10 min sampling by a SARAD RTM 1688 Radon/Thoron monitor, in contrast, revealed a sizeable area depleted in radon and 3 active areas of increased radon release in the lateral Mountain sides. These observed phenomena strengthen our assumption about the presence of an active geological structure in Tlamacas Mountain connected with a geodynamical processes in volcano Popocatepetl.

关键词： Radon Tlamacas Mexico Anomaly Popocatepetl Monitoring

Superheterodyne Amplification for Increase the Working Frequency

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Journal of Electromagnetic Analysis and Applications 2017年第3期9卷 43-52页

作者： Svetlana Koshevaya Vladimir grimalsky Yuriy Kotsarenko Margarita Tecpoyotl Jesus Escobedo Autonomous State University of Morelos Cuernavaca Mexico

The amplification of microwaves in n-GaAs films has been widely studied. On the other hand, using nonlinear parametric effects in microwave, millimeter, and THz ranges has a large potential. In this paper the resonant nonlinear phenomena are investigated in active n-GaAs semiconductor and in films on its base. The phenomena are the nonlinear interactions of space charge waves, including the frequency multiplication and mixing, and the three-wave interaction between two THz electromagnetic waves and a single space charge wave. This three-wave interaction results in the superheterodyne amplification of THz waves. The electron velocity in GaAs is the nonlinear function of an external electric field. If the bias electric field is more E0>Ecrit ≈3KV/cm , it is possible to obtain a negative differential mobility (NDM and space charge waves). The space charge waves have phase velocity of electrons equal to v0=v(E0), E0=V0/Lz , where V0 is the voltage, producing the bias electric field E0?in GaAs film. The superheterodyne amplification and the multiplication of microwaves are very promising for building active sensors in telecommunications system, radiometers, and radio telescopes. The superheterodyne mechanism has an advantage related to decreasing noise because of increasing of frequency in the process of amplification. It is used in the process of amplification of longitudinal space charge waves that in turn causes the transfer of energy from longitudinal wave into transverse one with increasing frequency. This is realized due to parametric coupling of two transverse waves and a single space charge wave in GaAs.

关键词： Space Charge Waves Superheterodyne Amplification