External Electromagnetic Wave Research Articles

ON THE EFFICIENCY OF WAVE-PARTICLE INTERACTION

The efficiency of acceleration of charged particles during cyclotron resonances and acceleration of particles in a vacuum without an external magnetic field are considered. It is shown that the statement formulated in Lawson-Woodward theorem that relativistic particles do not exchange energy with an external electromagnetic wave in a vacuum is not sufficiently justified.

Application of the quantum model of the rotating wave approximation to the generation of spin waves in nanowires

The paper simulates systems in which two types of spin waves can occur, propagating in opposite directions. To achieve this, the quantum slow-wave approximation is employed, allowing for the determination of the probability distribution of occupied states in a quantum two-particle system subjected to perturbations, commonly referred to as Rabi oscillations. This model is specifically applied to a configuration of parallel nanowires exposed to an external electromagnetic wave within the microwave range. The study explores a potential application of the investigated nanostructures in the development of a device for detecting electromagnetic fields.

Electrical and Magnetic Properties of Materials for Electromagnetic Interference

General aspects about electromagnetic interference (EMI) have shown that various electronic and electrical devices, in the field of communications are very sensitive to many sources (emissions) of external electromagnetic waves with various bands of frequency components. All electrical equipment using radio communication contains intentional emitters and sensitive receivers. Since electrical and magnetic materials have different properties, the objective of this paper is to explore the shielding effectiveness of some materials and to suggest new compounds that satisfies the effective shielding requirements.

PHASE SYNCHRONIZATION OF PARTICLES AT CYCLOTRON RESONANCES

Subject and Purpose. The effects considered concern phase synchronization of electrons in an ideal plasma subjected to the action of an external uniform, d. c. magnetic field. Two modes of the synchronization are discussed, specifically one by an external electromagnetic field and the other by the cyclotron radiation emitted by the electrons. The purpose is to compare these forms of synchronization and their effects on plasma stability. Methods and Methodology. The plasma is represented as a set of coupled oscillators whose dynamics is described via coupled differential equations. Assuming the coupling between the oscillators to be weak we find analytical solutions to the equation, further performing a stability analysis which exploits standard approaches of the dynamical systems theory. The solutions found are validated through corresponding numerical simulations. Results. As has been found, an external electromagnetic wave may be capable of guiding the particles toward phase synchronization, which can lead to formation of phased bunches. This mechanism of particle grouping may prove to be more efficient, in terms of scale times of synchronization, if compared with known mechanisms exploiting relativistic effects. Additionally, we show that the cyclotron radiation emitted by the charged particles (which is often disregarded because of its smallness) can lead to self-phase synchronization of the electrons. Moreover, should the density of charged particles in the ensemble be sufficiently high, an instability can arise, potentially disrupting the ensemble. Estimates have been provided of the level of random fluctuations capable of undermining the synchronization process and plasma dynamics stabilization. Conclusions. The most significant finding of this analysis is the emergence of low-frequency oscillations in the charged oscillators set, followed by an onset of the plasma instability when the plasma density exceeds a certain critical value. Within that scenario, the ensemble of oscillators sitting in the external magnetic field is no longer held together by the field. The effect should be taken into account in applications related to plasmas of a relatively high density.

THE ROLE OF HIGHER MOMENTS ON THE DISTRIBUTION OF PARTICLES IN THE SPACE OF IMPULSES AT CYCLOTRON RESONANCES

The results of the analysis of the dynamics of charged particles under conditions of cyclotron resonances in the field of an intense electromagnetic wave are presented. Particular attention is paid to regimes with dynamic chaos. It is shown that there are two qualitatively different regimes. The appearance of the first one is due to the overlap of nonlinear cyclotron resonances. The second mode is related to intermittency. The moments and spectra of each of these regimes are determined. It is shown that with an increase in the intensity of an external electromagnetic wave, the first regime appears at the beginning and only then the second regime appears. A characteristic feature of the second regime is intermittency. Steps appear on the time dynamics of pulses in the second mode. It is shown that the spectra in the second mode are narrower than in the first mode. A characteristic feature of the second regime (the regime with intermittency) is the fact that the higher moments turn out to be larger than the lower moments. In the first regime, the highest moments decrease rapidly. To find the particle momentum distribution function, the generalized Fokker-Planck equation was used. Solutions of this equation are written out for some important cases.

Effect of Electron-impurity Interaction on the Optical Absorption in A Quasi-one-dimensional Electron System

In this work, we investigated the optical absorption in a quasi-one-dimensional system subjected to an external electromagnetic wave. The optical absorption coefficient was calculated by using the perturbation theory taking account of the effect of the electron - impurity interaction. The numerical result for the GaAs/AlAs cylindrical semiconductor quantum wire showed the presence of the resonant absorption peaks. The full width at half maximum (FWHM) decreased with increasing the wire radius and increases with increasing temperature. In particular, in the limit of large wire radius, the contribution of transitions between electronic subbands to the absorption spectrum becomes identical, t meaning that the system tends to behave as a bulk (there-dimensional) system when the confinement length is large. The obtained results are of significance for further studies and applications of the low dimensional systems in nano-optoelectronic devices.

A study protocol for investigating the effects of mobile phone-originated electromagnetic waves on thyroid gland and thyroid hormone activities in the brain

With widespread users across the globe, topic on the impact of mobile phone in particular regarding its electromagnetic wave radiation deserves a priority. Carcinogenic effects of the electromagnetic wave radiation have been suggested by multiple studies. Effects of the radiation are to involve thermal and non-thermal pathways. Among human organs, thyroid gland is susceptible to the radiation exposure due to its location being superficial and close to the radiation transmitter. Previous studies have indicated the correlation between the mobile phone radiation and thyroid dysfunctions. However, a conclusion that the electromagnetic wave radiation is the causative agent of the thyroid dysfunctions has not been reached. Most of the study are unable to remove the influence of the external electromagnetic wave radiation. Hence, this study aimed to perform an investigation with true experimental design using animal model in an anechoic chamber – an isolated chamber which could minimize the electromagnetic wave noise from the outside. In this article, we present the description of the anechoic chamber along with the research protocols. Parameters affecting the investigation, including signal frequencies inside the chamber and specific absorption rate are also measured.

Analysis of the Terminal Response Characteristics of the Twisted Three-Wire Cable Excited by a Plane Wave Field

A twisted three-wire cable model with uniform twisting characteristics is proposed in this paper, and its terminal response under external electromagnetic wave irradiation is calculated using the TLM method based on Taylor model. The triple-stranded triple-helix structure is determined in the method and the parametric equations of the twisted wire bundle in the Cartesian coordinate system are provided. Then, the frequency domain equations for the voltage and current of the twisted three-wire cable under field-to-wire coupling are derived and extended to apply to scenarios with arbitrary polarization and irradiation in the incident direction based on the transmission-line theory. Finally, the response laws of the twisted three-wire wire with different cable lengths, termination loads, and pitches coupling under external electromagnetic wave irradiation are studied. A uniform twisted three-wire cable can suppress the increased induced current on the cable. In addition, the excellent characteristics of the twisted three-wire cable in terms of immunity to electromagnetic interference are also verified by comparing the frequency domain response with that of a parallel three-wire cable.

A study protocol for investigating the effects of mobile phone-originated electromagnetic waves on thyroid gland and thyroid hormone activities in the brain

With widespread users across the globe, topic on the impact of mobile phone in particular regarding its electromagnetic wave radiation deserves a priority. Carcinogenic effects of the electromagnetic wave radiation have been suggested by multiple studies. Effects of the radiation are to involve thermal and non-thermal pathways. Among human organs, thyroid gland is susceptible to the radiation exposure due to its location being superficial and close to the radiation transmitter. Previous studies have indicated the correlation between the mobile phone radiation and thyroid dysfunctions. However, a conclusion that the electromagnetic wave radiation is the causative agent of the thyroid dysfunctions has not been reached. Most of the study are unable to remove the influence of the external electromagnetic wave radiation. Hence, this study aimed to perform an investigation with true experimental design using animal model in an anechoic chamber – an isolated chamber which could minimize the electromagnetic wave noise from the outside. In this article, we present the description of the anechoic chamber along with the research protocols. Parameters affecting the investigation, including signal frequencies inside the chamber and specific absorption rate are also measured.

Directional electromagnetic interference shielding of asymmetric structure based on dual-needle 3D printing

Some special electronic equipment not only need to avoid the interference of external electromagnetic waves (EMWs), but also need to transmit effective signals. Therefore, the development of directional electromagnetic interference (EMI) shielding materials has a great prospect. The asymmetric structure, consisting of the porous magentic rGF (reduced graphene oxide and Fe3O4) layer and the dense electrical conductivity rGM (reduced graphene oxide and MXene) layer, was constructed by dual-needle 3D printing technology. After encapsulation and curing with polydimethylsiloxane (PDMS), the rGF/rGM/PDMS composites were prepared. When the ratio of rGF and rGM layers is 6:4, the SE values of rGF-6/rGM-4/PDMS composites are 38.75 dB and 30.79 dB respectively when EMWs are incident on the rGF layer and rGM layer respectively, and the ΔSE of which is about 8 dB. The results showed that the asymmetric structure composed of porous magnetic layer and dense deeply electric conductive layer could generate a special process of "weak reflection-absorption-strong reflection-reabsorption" for incident EMW. At the same time, the simulation results of the waveguide method validated the experimental results, and further explained the directional EMI shielding mechanism of asymmetric structure. For the first time, this work designs an asymmetric structure based on the double needle 3D printing technology, which provides useful inspiration for the structural design and potential application of directional EMI shielding materials.

Extremely Short Optical Pulses in Carbon Nanotubes Taking into Account the Multiphoton Absorption in the Presence of Random Stress

In this paper, the authors study the influence of a random stress on the parameters of an extremely short optical pulse as it propagates in a nonlinear medium with carbon nanotubes, taking into account the processes of multiphoton absorption and pumping by an external electromagnetic wave. The dependence of the intensity and width of the pulse field on the number of photons, as well as on the amplitude of the pump pulse, is analyzed.

Influence of a Strong Electromagnetic Wave on the Nonlinear Absorption coefficient of Strong lectromagnetic Waves Caused by Electrons Confined in Cylindrical Quantum Wires

The nonlinear absorption coefficient of a strong electromagnetic wave caused by electrons confined in cylindrical quantum wires is theoretically studied by using the quantum kinetic equation for electrons. Analytic expressions of the nonlinear absorption coefficient of a strong electromagnetic wave caused by electrons confined in a cylindrical quantum wire with a parabolic potential for electron-optical phonon scattering is obtained, that the dependence of the nonlinear absorption coefficient on the intensity E0 and the frequency Ω of the external strong electromagnetic wave is strongly and nonlinearly. The analytic expressions are numerically calculated and discussed for a GaAs/GaAsAl quantum wire. The results are compared with those for normal bulk semiconductors and quantum wells to show the differences.

Детектирование субтерагерцевых колебаний на основе гетероструктуры антиферромагнетик/тяжелый металл

We study a model of a detector of subterahertz electromagnetic waves based on an array of heterostructures containing an antiferromagnet and a heavy metal. We show that the operating frequency of the detector can be tuned by a constant magnetic field applied in the direction of the easy magnetization axis of the antiferromagnet. The dependence of the rectified voltage on the frequency of the external electromagnetic wave for different values ​​of the constant magnetic field is resonant in nature, and an increase in the constant magnetic field leads to an increase in the resonance peak. It is shown that the use of an array of antiferromagnets in the form of a comb structure makes it possible to increase the level of the rectified output voltage.

Modeling of plasmon resonance of silver nanoparticles on a silicon surface

Silver nanoparticles have unique optical properties due to resonance effects that arise due to the presence of conduction electrons in them. When these electrons interacte with photons, they can create localization of electric fields at the interfaces with the environment. Silver nanoparticles deposited on a transparent substrate are often used for research, while Ag nanostructures on Si are studied in this work. They have great potential for practical applications. The interaction of light with nanostructures can be described using various models (pseudo-dielectric functions, effective medium, thin-layer structures, etc.) and optical methods for the experimental determination of their parameters (refractometry, spectrophotometry). Bulk plasmon resonance is considered in this work, which is excited when plasmons are excited at their resonant frequency by an external electromagnetic wave. Calculations were performed for different diameters of silver nanoparticles on a silicon substrate with different structure periods. The calculated spectra are in good agreement with the experimental data of the obtained samples. As a result of the plasmon resonance modeling, the position of the plasmon resonance depends on the density of the arrangement of silver nanoparticles, with an increase in the displacement resonance towards the long-wavelength region.

Ultrasound-Mediated Cancer Therapeutics Delivery using Micelles and Liposomes: A Review.

Existing cancer treatment methods have many undesirable side effects that greatly reduce the quality of life of cancer patients. This review will focus on the use of ultrasound-responsive liposomes and polymeric micelles in cancer therapy. This review presents a survey of the literature regarding ultrasound-triggered micelles and liposomes using articles recently published in various journals, as well as some new patents in this field. Nanoparticles have proven promising as cancer theranostic tools. Nanoparticles are selective in nature, have reduced toxicity, and controllable drug release patterns making them ideal carriers for anticancer drugs. Numerous nanocarriers have been designed to combat malignancies, including liposomes, micelles, dendrimers, solid nanoparticles, quantum dots, gold nanoparticles, and, more recently, metal-organic frameworks. The temporal and spatial release of therapeutic agents from these nanostructures can be controlled using internal and external triggers, including pH, enzymes, redox, temperature, magnetic and electromagnetic waves, and ultrasound. Ultrasound is an attractive modality because it is non-invasive, can be focused on the diseased site, and has a synergistic effect with anticancer drugs. The functionalization of micellar and liposomal surfaces with targeting moieties and the use of ultrasound as a triggering mechanism can help improve the selectivity and enable the spatiotemporal control of drug release from nanocarriers.

Slow Light Rainbow Trapping in a Uniformly Magnetized Gyromagnetic Photonic Crystal Waveguide

We present a hybrid gyromagnetic photonic crystal (GPC) waveguide composed of different GPC waveguide segments possessing various cylinder radii and waveguide widths but biased by a uniform external magnetic field. We demonstrate in frequency and time domains that based on the strong coupling of two counter-propagating topologically protected one-way edge states, the intriguing slow light rainbow trapping (SLRT) of electromagnetic (EM) waves can be achieved, that is, EM waves of different frequencies can be slowed down and trapped at different positions without cross talk and overlap. More importantly, due to the existence of one-way edge states, external EM waves can be non-reciprocally coupled to the SLRT waveguide channel, although the incident position of the EM wave is far away from the waveguide channel. Besides, the frequency range of the slow light states can also be easily regulated by tuning the intensity of an external magnetic field, which is very beneficial to solve the contradiction between slow light and broad bandwidth. Our results can be applied to the design of high-performance photonic devices, such as an optical buffer, optical switch, and optical filter.

Enhance sensitivity to illumination and synchronization in light-dependent neurons* *Project supported by the National Natural Science Foundation of China (Grant No. 12062009).

When a phototube is activated to connect a neural circuit, the output voltage becomes sensitive to external illumination because the photocurrent across the phototube can be controlled by external electromagnetic wave. The channel currents from different branch circuits have different impacts on the outputs voltage of the neural circuit. In this paper, a phototube is incorporated into different branch circuits in a simple neural circuit, and then a light-controlled neuron is obtained for further nonlinear analysis. Indeed, the phototube is considered as exciting source when it is activated by external illumination, and two kinds of light-sensitive neurons are obtained when the phototube is connected to capacitor or induction coil, respectively. Electric synapse coupling is applied to detect possible synchronization between two functional neurons, and the energy consumption along the coupling channel via resistor is estimated. The analog circuits for the two kinds of light-sensitive neurons are supplied for further confirmation by using Multisim. It is found that two light-sensitive neurons and neural circuits can be synchronized by taming the coupling intensity carefully. It provides possible clues to understand the synchronization mechanism for eyes and artificial sensors which are sensitive to illumination. Finally, a section for open problems is supplied for further investigation about its collective behaviors in the network with/without synapse coupling.

Self-consistent plasma boundary distortions during the interaction of a normally incident electromagnetic beam with a nonlinear surface charge

The nonlinear interaction of an electromagnetic beam with a sharp boundary of a cold plasma is here investigated under simplest ideal conditions. New coupled equations are derived for the description of a self-consistent behavior of a high frequency irradiation with an electrostatic field of nonlinear surface charge taking into account a possible deformation of a plasma boundary during the external influence. It is discovered that the angle and coefficient of the reflection are changed for the normal incidence of the external electromagnetic wave. Intensities of the second and third harmonics are analyzed under the influence of a nonlinear surface charge. The self-consistent solution of the performed boundary problem is found with taking into account the possibility of deforming the plasma boundary under external influence of the electromagnetic beam for cases when the discovered physically correct spatial distribution provides the existence of arising electrostatic fields of surface charge perturbations.

Optimized microwave absorption properties by tailoring the morphology of carbon coated TiC nanoparticles by N2 pressure

Increasing the dielectric loss capacity plays an important role in enhancing the electromagnetic absorption performance of materials. It remains a challenge to simultaneously introduce multiple types of dielectric losses in the material. In this work, we show that the atomic and interfacial dipole polarizations can be simultaneously enhanced by substituting N species into both carbon coating layers and bulk TiC lattices of a core-shell TiC@C material. Additionally, substitution of N species results more exposed TiC(111) facets and refines the TiC grain sizes in the bulk material, which is beneficial for enhancing the scattering of the external electromagnetic waves. The maximum reflection loss of the N substituted TiC@C material is measured as −47.1 dB with an effective absorbing bandwidth of 4.83 GHz at 1.9 mm, which illustrates a valuable way to further tuning the electromagnetic absorption performance of this type of materials.

Analysis of the electromagnetic wave illumination on the transmission lines with nonlinear terminations

AbstractIn this paper, an unconditionally stable time-domain method is proposed to investigate the external electromagnetic (EM) field illumination on the nonlinearly loaded transmission lines. In the proposed algorithm, the field to line coupling equations and linear/nonlinear boundary conditions are incorporated and expressed in a matrix form. The derived differential matrix equations are then discretized and solved using the proposed finite difference time domain (FDTD) method approach. The discretized nonlinear matrix equations are also solved by applying a globally convergent iterative method to ensure the stability of the method. Moreover, the experimental investigations are conducted using a transverse EM (TEM) cell for a single microstrip line and a power detector circuit as a nonlinearly loaded transmission line to confirm the accuracy and stability of the proposed method. With the merit of satisfactory accuracy and unconditional stability for the entire range of time steps, the presented approach would be applicable for analyzing the microwave linear/nonlinear circuits subjected to the external incident EM wave.