Magnetic Wave Research Articles

The wave mode transition of argon helicon plasma

In this paper, multiple wave modes and transitions of argon helicon plasma excited by a half right-helical antenna in a system without any reflection endplate are investigated experimentally and theoretically at increasing radio frequency (RF) powers and external magnetic fields. Experiments show that above a critical magnetic field strength and pressure (about 250 G and 0.3 Pa in this work), two to four distinct wave-coupled modes and transitions were observed at increasing RF powers and/or magnetic fields. Theoretical analysis based on the dispersion relationship shows that in a high magnetic field, the helicon wave of the lowest order of axial eigenmode is always excited first, then the higher-order axial or radial mode; hence, the plasma density increases after mode jumping. There are two mechanisms responsible for the wave mode transitions in the present system, i.e. axial and radial mode transitions due to the change of axial and radial wavenumbers from a lower eigenmode to a higher one. A higher plasma density and magnetic field are helpful for achieving more higher-order modes of helicon waves.

Anomalies in the magnetostrictive modulation of love surface acoustic waves

A magnetic surface acoustic wave (SAW) sensor is built by growing a 100 nm galfenol (Fe72Ga28) film by sputtering between the interdigitated transducers of a SAW delay line. Love waves are produced when the shear waves excited on the piezoelectric substrate are guided by a 3.1 μm layer of amorphous SiO2. Due to the magnetostrictive nature of galfenol deposited on top, the application of magnetic fields modulates the propagation of the mechanical excitations along the sensor by the strain coupling. By introducing the delay line in a feedback loop circuit, these changes are studied as resonant frequency variations. Magnetic field cycles of ±40 mT are applied to the sample and the resonant frequency shift is tracked simultaneously. The sensor exhibited hysteretic frequency behavior that depends on the orientation of the applied magnetic field relative to the direction of Love wave propagation. In the configuration in which the wave vector and the applied field form an angle of 45°, the resonant frequency seems to increase with the magnetization induced by the external field. When the wave vector propagation is parallel to the field, two positive peaks appear close to the coercive field of the film, which has not been reported before. This is probably due to a more complex relationship between the acoustic wave and the magnetic state of the film which could be exploited to give rise to new models of magnetic sensors.

Properties of an Interplanetary Shock Observed at 0.07 and 0.7 au by Parker Solar Probe and Solar Orbiter

The Parker Solar Probe (PSP) and Solar Orbiter (SolO) missions opened a new observational window in the inner heliosphere, which is finally accessible to direct measurements. On 2022 September 5, a coronal mass ejection (CME)-driven interplanetary (IP) shock was observed as close as 0.07 au by PSP. The CME then reached SolO, which was radially well-aligned at 0.7 au, thus providing us with the opportunity to study the shock properties at different heliocentric distances. We characterize the shock, investigate its typical parameters, and compare its small-scale features at both locations. Using the PSP observations, we investigate how magnetic switchbacks and ion cyclotron waves are processed upon shock crossing. We find that switchbacks preserve their V–B correlation while compressed upon the shock passage, and that the signature of ion cyclotron waves disappears downstream of the shock. By contrast, the SolO observations reveal a very structured shock transition, with a population of shock-accelerated protons of up to about 2 MeV, showing irregularities in the shock downstream, which we correlate with solar wind structures propagating across the shock. At SolO, we also report the presence of low-energy (∼100 eV) electrons scattering due to upstream shocklets. This study elucidates how the local features of IP shocks and their environments can be very different as they propagate through the heliosphere.

Effectiveness of Modes of Radio Broadcasting in Gain and Retention of Knowledge About Child Care Message

Abstract: India is dominantly a country of villages. There is a great necessity for transmitting latest scientific knowledge about agriculture and related fields among the farming communities. Today we have many problems- high rate of illiteracy, accelerating population growth which eats into any gain that educational expansion may bring, increasing pressures on admissions at all stages, explosion in knowledge necessitating change and review of curricula and teaching method, urban – rural imbalance, wastage in education need for raising standards and the criterion of an environment favourable to social change and capable of softening its harsher incidences. The mass media are supremly adapted to adult education. Radio is the transmission and reception of signals by means of electric waves without the use of connection wires. Therefore, this study was undertaken with a view to find out relative effectiveness of three mode of presentation

Cell phone radiation effect on osteocalcin and bone alkaline phosphatase

Background: Electromagnetic fields are forces associated with moving electric charges and have electrical, magnetic components and contain electromagnetic energy, one of which is radio frequency (RF) energy which is commonly used in telecommunications. Cell phones are one of the RF electromagnetic radiation devices that can emit 90-2450 MHz waves and are often placed near the head. The human body works like an electromagnetic field in that each cell has its own electrical circuit characteristics. As the number of electromagnetic radiation devices in the environment increases, the electromagnetic balance in the human body may be disturbed by the magnetic waves produced by cell phones. Electromagnetic radiation is known to have the ability to induce oxidative stress, which is characterized by the accumulation of reactive oxygen species (ROS) in tissues. The accumulation of ROS in the body leads to osteoblast cell death. Osteoblasts are needed for mineralization of the extracellular matrix during bone growth. Therefore, bone growth is not optimal and can caused malocclusion. Purpose: This study aims to evaluate the relationship between electromagnetic radiation and osteocalcin and bone alkaline phosphatase (BALP) serum levels. Methods: Experimental laboratory research with a pre- and post-control group design approach was carried out on 12 Rattus norvegicus Wistar strain. Osteocalcin and BALP serum levels were calculated before and after treatment. This study used the t-test as a comparative study (p<0.05). Results: There are significant differences in osteocalcin and BALP values between the treatment groups before and after treatment. Conclusion: Cell phone radiations (electromagnetic field exposure) reduce osteocalcin and BALP serum levels.

Alloying effect of rare-earth tritellurides on the charge density wave and magnetic properties

Among many van der Waals materials rare-earth tritellurides (RTe3) allow studying several phenomena like magnetic, superconducting, and charge density wave (CDW). These studies show the effect of cationic alloying of antiferromagnetic RTe3 for fully tunable near room-temperature CDW properties. DyxGd1−xTe3 and DyxTb1−xTe3 alloys were synthesized through a chemical vapor transport technique, and the rare-earth element composition was controlled by changing the ratio of rare-earth metal reagents. The results show that the lattice parameters can be continuously tuned with the composition of the rare-earth cations leading to the variation of the internal chemical pressure. Temperature-dependent Raman spectroscopy and electric transport measurement show that the CDW transition temperature (TCDW) of RTe3 alloys varies with lattice parameters/chemical pressure spanning across 300–380 K. Additional magnetism studies offer the first insights into the magnetic ordering in RTe3 alloys. The emergence of multiple magnetic transitions implies complex magnetic interactions that arise from interactions between different rare-earth elements. Overall findings introduce ways to control the CDW behavior and provide valuable insights into the magnetic ordering in RTe3 alloys, contributing to further investigation and a better understanding of their properties.

Free vibration of ferromagnetic functionally graded cylindrical shells subjected to magnetic and temperature fields

The free vibration characteristics of functionally graded cylindrical shells under magnetic and temperature fields are investigated. According to Donnell’s theory, the kinetic energy, deformation energy, and their variational expressions are obtained. Based on the electromagnetic elasticity theory, the eddy current electromagnetic and magnetization force models are established. Using Hamilton’s principle, the magneto-thermo-elastic free vibration partial differential equations are derived. The modal frequency differential matrix equation with diverse boundary conditions is derived from the Galerkin integral technique. Through numerical examples, the curves and three-dimensional surface diagrams depicting the variations for the natural frequency with diverse parameters are obtained. The feasibility of the proposed solution method in this paper is supported by literature examples. The influence of magnetic induction intensity, temperature, power-law index, wave number, and shell dimension on the natural frequencies are determined.

Contribution of the Magnetic Subsystem to the Generation of Longitudinal Acoustic Waves during Domain Wall Motion in Yttrium Orthoferrite

Purpose. Modern technologies in their development are increasingly in need of increasing the speed of processing and recording information. An alternative to semiconductor methods is magnetic memory based on changing magnetic moments. The speed of magnetization reversal is determined by the speed of motion of domain walls. The speed is maximum in weak ferromagnets. The purpose of this work is to study the effect of a magnetic wave generated by a moving domain wall on a longitudinal acoustic wave, taking into account the absorption of a magnetic wave in yttrium orthoferrite.Methods. The equation describing the effect of a magnetic wave generated by a moving domain wall on a longitudinal acoustic wave is solved using the following methods: the slowly varying amplitude method, the perturbation theory method, and the Lagrange method.Results. For an orthoferrite crystal, the contribution of the magnetic wave accompanying the motion of the domain wall in yttrium orthoferrite to the deformation of the amplitude of the longitudinal acoustic wave is calculated. This contribution in a bounded crystal, without taking into account the absorption of magnetic waves in the absence of the influence of acoustic waves on them, is of the order of 10-6 cm. In an unbounded crystal, the corresponding contribution, taking into account the absorption of magnetic waves, into the generation of longitudinal acoustic waves is of the order of magnitude 10-10 cm with a theoretical thickness of the domain wall D3 ≈ 10-6 cm.Conclusion. To study the mechanisms of the influence of a magnetic wave generated by a moving DW on a longitudinal acoustic wave, yttrium orthoferrite was taken. Since a weak ferromagnet is characterized by a significant increase in the magnetoelastic coupling when it overcomes the sound barrier. It is this circumstance that made it possible to experimentally observe the generation of elastic displacements by a moving domain wall. To develop devices for recording and processing information based on weak ferromagnets, it is necessary to fully investigate the mechanisms that affect the dynamics of a domain wall during its motion. Such a factor is the interaction of magnetic and acoustic waves with the domain wall, which can affect the quality of information processing. The evaluation of the contributions of these mechanisms can be used to develop the element base of devices for recording and processing information based on the magnetic memory of weak ferromagnets.

A numerical model for the electrical and shock wave characteristics of underwater pulsed spark discharge

Underwater pulsed spark discharge has been widely used in industrial fields as a source of shock waves or acoustic waves, and numerical modeling of the discharge and pressure wave characteristics is necessary to improve the application performance. In this paper, a numerical model is proposed that couples the circuit equation, the mass and energy conservation equations, and a momentum conservation equation based on the Rankine–Hugoniot conditions. A tabulated wide range equation of state and conductivity data of water are used, and various physical processes during the plasma channel expansion are considered, including the energy flow and mass exchange between the channel and the surrounding water due to thermal radiation, evaporation, and condensation. The model self-consistently solves the circuit current and voltage, the plasma channel parameters including composition, temperature, conductivity, pressure, etc., and the pressure profile at a certain distance from the discharge channel. The calculated results show good consistency with the experimental measurements, and three sets of experimental results from other literature are tested to further verify the applicability and effectiveness of the model.

Response of surface effect on plane wave reflection at the boundary of flexomagnetic substrate

The article delves into the reflection of bulk plane waves in a flexomagnetic slab with second-order gradient elasticity. Employing generalized Gurtin-Murdoch surface elasticity, the study provides analytical insights into amplitude ratios and energy flux ratios for reflected bulk waves. The investigation focuses on understanding the behavior and energy conversion of incident bulk waves in the reflected P-SV system, highlighting the influences of residual surface stress, surface elasticity, and flexomagnetic polarization. The outcomes of the study indicate the high amplitude in the presence of residual stress. The findings contribute to fundamental knowledge for nanoscale piezomagnetic structures and potential applications in magnetic acoustic wave devices.

The enhanced nonreciprocal radiation in a grating structure containing a Weyl semimetal film under conical incidence

The enhanced nonreciprocal radiation in grating structure for light under conical incidence is investigated. The basic structure is composed of a one-dimensional grating on a continuous Weyl semimetal planar and a thick metallic mirror. The results show that near-perfect nonreciprocal radiation can be observed for transverse electric wave, which cannot be achieved for light in traditional incidence. Such effect results from the guided mode resonance (GMR) excited inside the grating, demonstrated by studying the electromagnetic field amplitude distribution. Moreover, the strong nonreciprocity is also stable for the geometric parameters in a wide varying range, lowering the cost of manufacture. Most of important, the proposed scheme could be employed to realize enhanced nonreciprocity for both TM polarization and TE polarization with different resonant wavelengths along with the same resonant wavelength. The concepts proposed here should pave the way to the development of polarization-dependent and polarization-independent as well as dual-polarization nonreciprocal emitters.

Electric Cable Insulator Damage Monitoring by Lasso Regression

Since the discovery of electricity, electric cables have become ubiquitous in human constructions, from machines to buildings. Insulators play a crucial role in ensuring the proper functioning of these cables, so it is important to monitor their possible damage, which can be caused by environmental contamination, severe temperature variations, and electrical and mechanical stress. While shunt conductance is a direct health indicator of cable insulation, measuring the cable average shunt conductance is not sufficient for the detection of localized insulator damage, since localized conductance variations are diluted over a long cable length in such measurements. The objective of this paper is to assess the feasibility of reflectometry techniques for the monitoring of insulator damage in electric cables. To this end, the estimation of localized conductance variations is investigated based on electrical measurements made at one end of a cable. To avoid estimating a large number of discretized conductance values along a long cable, the proposed method relies on sparse regression, which automatically focuses on localized conductance variations at unknown positions caused by accidental insulator damage. In order to efficiently apply sparse regression techniques, the telegrapher’s equations describing electric wave propagation in cables are transformed through several steps into a simple linear regression form. Then, Lasso (Least Absolute Shrinkage and Selection Operator) regression is applied to process the voltage and current data collected at a single end of the monitored cable. Numerical simulations show the potential of this method for fast estimation of localized shunt conductance variations.

Generator of Electricity Current Based on the New Axioms and Laws

The Theory of new Axioms and Laws contains 2 new Axioms and 8 Laws and it is invented by the same author. The classical axiom (Maxuell 1864) states that the uniform vortex is closed and verifies the Classical Field Theory. In contrast, the first new axiom (Axiom1) asserts that the ununiform vortex is always open and, on this basis, develops a new Theory of Open vortices. The second new axiom (Axiom2) shows that open vortices in nature ( not in technic) are mutually orthogonal. On this basis, the electron is defined as orthogonal to the proton. The Law1, applied to the electron, affirms that a decelerating transverse open vortex generates an accelerating longitudinal vortex in its center. As one of a result of the decelerating transverse vortex, the electron becomes a strong eccentric. The center of the body moves from the Geometric center to a new center, which is the center of Gravity. This means that during its pulsation, this eccentric body emits a transverse electric wave with a greater amplitude from the convex side of the eccentric spiral than from its flattened side. Other of result is that the eccentric electron has an open active end of its decelerating transverse vortex. This means that for the flowing of an Electric wave only 1 axis (coordinate) phasing and ordering is required. Therefore, the electrons arrange their open ends (tails) towards the positive end of a conductor and the movement of their own Electric wave is also to the positive end of the Conductor. But the phenomenon of induction of Electric current is connected with the phasing of the electrons along the 3 axes. In the case of outer hitting of Magnetic lines, electrons arrange themselves so that their axes are parallel to outer Magnetic lines and are at a minimal distance from them. What’s more- the existence of phenomena induction is direct evidence of exactly this structure of the electron. The inner structure of the electron as an open decelerating very eccentric vortex is what causes it to react to the external impact from lines of force of an external Magnetic field, as a particle possessing some internal intelligence. On this base, the author proposes to construct a Modified Conductor using a grid of internal Magnetic lines. When electrons pulsate in Time, they hit these Magnetic lines. They will rotate so that they will phase along the 3 axes (3D) and thus imitate induct Electricity current.

Analysis of magnetohydrodynamic phenomena in a single spatial electromagnetic field

The paper presents the results of the analysis of the disinfection of water by a pulsed single spatial electromagnetic field. The origin of the fluid pressure in the pipe is calculated and graphically presented as the interaction of a single spatial field and the current of moving charges. It is proved that a single spatial field enhances the process of dissociation of water in a liquid solution. The orbital electrons of two hydrogen atoms and one oxygen atom of water create a strong inhomogeneous electric field around themselves, which leads to the separation of the liquid solution and the compounds contained in it into elements. The purpose of the work is to study magneto hydrodynamic phenomena spatial electromagnetic field disinfection of water by a single spatial electromagnetic field, The theory of a single spatial field involves the interaction of four fields of pulsed electromagnetic, pulsed electric, permanent magnetic and gravitational. The theory of a single spatial field is substantiated, which allows us to consider the issues of effective disinfection, desalination and purification of water, as well as to study the effects of electric, magnetic fields and electromagnetic waves on physical, chemical and biological processes occurring in liquids.

A dual functional tunable terahertz metamaterial absorber based on vanadium dioxide.

A dual-functional switchable metamaterial absorber (MMA) based on vanadium dioxide (VO2), which achieves flexible switching between broadband absorption and four-band absorption by adjusting the VO2 conductivity, was proposed. The device has a broadband absorption function when VO2 is in the metal phase, and the conductivity is 3 × 105 S m-1. Numerical simulation shows that the absorption rate of the device reaches over 90% in the frequency range of 3.36-6.98 THz. The absorber exhibits polarization insensitivity and wide-angle absorption to transverse electric (TE) and transverse magnetic (TM) waves. When VO2 is in the insulator phase, and the conductivity is 3 × 102 S m-1, the device switches to a narrowband absorber with a band-efficient absorption function. Numerical simulation shows that the device has an absorption rate of 99.7% at 2.39 THz, 98.3% at 2.83 THz, 95.6% at 3.84 THz, and 96.1% at 4.61 THz. It can be used as a sensor with high sensitivity. In addition, to verify the absorption mechanism of the absorber, we introduced impedance matching theory to analyze the device. Finally, the influence of structural parameters on the performance of resonators was investigated. Through the joint action of multi-layer structures, the proposed MMA concentrates broadband and narrowband absorption functions on one device, achieving flexible switching between tasks without changing the structure. The switchable metamaterial absorber designed through simple tuning methods has broad application prospects in stealth technology and thermal emitters. It provides a wide range of ideas for the design of terahertz functional devices.

The Erratic History of Electroencephalography

The history of electroencephalography begins around 1850 with a supposition of Emil du Bois-Reymond concerning the transfer of information by electric currents over the nerve to the effector. Luigi Galvani in Bologna showed with his frog legs experiments 1786 indeed the existence of animal electricity. Richard Caton in Liverpool placed in 1875 as the first electrodes on the brains of rabbits and was able to record the electrical brain activity. Caton received little attention for his research and left with his animal experiment aversion the field. In contrast to Caton, Adolf Beck in Kraków, got a huge attention for his recordings of the electrical activities of the frog brain. The most interesting response to his important paper of 1890 came from Vasili Danilewski from Charkov, mentioning his unpublished doctoral thesis of 1877. He did his dog recordings before Beck, but one year after Caton who send him his abstract, remaining that he discovered before him electric brain waves. Colleagues of Danilewski such as Práwdicz- Neminski from Kyiv performed also adequate work in this field, but due to Stalin's dogmatic regime, electrophysiology became prohibited and disappeared in Russian. Jewish Adolf Beck, now professor in Lwów, experienced there in war time in 1940 dangerous times and ultimately the Nazi’s came for him. His son succeeded to hand him a cyanide capsule to save him from the gas chamber. By the tragedies of the war in Poland and the split between East and West Europe, Beck and his work go lost. Hans Berger began in Jena with brain recordings in humans and in 1927 he exclaimed ‘I can record brain actvity from an intact human skull’. This was replicated abd agreed upon by Edgar Adrian in 1934, and Berger received international fame, but not in Germany. The often authoritative Berger hated the Nazi’s and was suspended by the regime. He came in a severe depression and ended his life by hanging in June 1941. In this heavy war time, electrophysiology moved to the USA. Frederic and Erna Gibbs at Harvard got, with their studies of epilepsy in 1934 a breakthrough in clinical electroencephalography, Alfred Loomis and Herbert Jasper used the electrical brain actvity to identify several stages of sleep. Later, Jasper performed in Montreal, with neurosurgeon Wilder Penfield, important research on focal epilepsies. After the second world war, around 1950, electroencephalography blossomed up, in the USA as well as in Europe. Recording electroencephalograms for studying the functioning of the brain and in particular investigating domains of sleep and epilepsy. It became common that almost every university and hospital had a resording device. That electroencephalography was a mature methodology, was demonstrated by great discoveries for example through the finding of REM sleep by Kleitman and Aserinski in 1953.

A case report on Creutzfeldt-Jacob disease: early diagnosis through multidisciplinary lens

Background: Creutzfeldt Jacob disease is a rapidly progressive neurodegenerative disorder, which is invariably fatal and results in death within 1 year of onset. The patient presents with a variety of non-specific neuropsychiatric symptoms, such as myoclonus, cerebellar symptoms, visual impairment, and behavioral abnormalities. The symptoms are rapidly progressive and cause early functional impairment in the patient. Case Presentation: In this report, we discussed a case of 49-year-old male presented with multiple neuropsychiatric symptoms. After a series of extensive diagnostic examinations and follow-up, the patient was diagnosed as having probable sporadic Creutzfeldt-Jakob disease based on 2018 Centres for Disease Control and Prevention criteria, with key findings of myoclonus, behavioral and cerebellar problems, visual abnormalities, abnormal hyperintensity signals on diffusion-weighted magnetic resonance imaging and characteristic electroencephalogram waves. CSF 14-3-3 protein was significantly high. Conclusion: Sporadic CJD is a rare and fatal rapidly progressive neurodegenerative disorder, that claims prompt and precise diagnosis to help clinicians distinguish it from potentially treatable neuropsychiatric disorders. This aspect elevates the significance of our report, as it aids not only the medical professionals but also the affected families. Early diagnosis enables the family to prepare for the disease course and appropriate management strategies.

Elucidation on step-out phenomenon of magnetic strain wave gear by multi flexible body dynamics and displacement measurement

Elucidation on step-out phenomenon of magnetic strain wave gear by multi flexible body dynamics and displacement measurement

Measuring the electrophoretic mobility and size of single particles using microfluidic transverse AC electrophoresis (TrACE).

The ability to measure the charge and size of single particles is essential to understanding particle adhesion and interaction with their environment. Characterizing the physical properties of biological particles, like cells, can be a powerful tool in studying the association between the changes in physical properties and disease development. Currently, measuring charge via the electrophoretic mobility (μep) of individual particles remains challenging, and there is only one prior report of simultaneously measuring μep and size. We introduce microfluidic transverse AC electrophoresis (TrACE), a novel technique that combines particle tracking velocimetry (PTV) and AC electrophoresis. In TrACE, electric waves with 0.75 to 1.5 V amplitude are applied transversely to the bulk flow and cause the particles to oscillate. PTV records the particles' oscillating trajectories as pressure drives bulk flow through the microchannel. A simple quasi-equilibrium model agrees well with experimental measurements of frequency, amplitude, and phase, indicating that particle motion is largely described by DC electrophoresis. The measured μep of polystyrene particles (0.53, 0.84, 1, and 2 μm diameter) are consistent with ELS measurements, and precision is enhanced by averaging ∼100 measurements per particle. Particle size is simultaneously measured from Brownian motion quantified from the trajectory for particles <2 μm or image analysis for particles ≥2 μm. Lastly, the ability to analyze intact mammalian cells is demonstrated with B cells. TrACE systems are expected to be highly suitable as fieldable tools to measure the μep and size of a broad range of individual particles.

Search for anomalous chiral effects in heavy-ion collisions with ALICE

The interplay between the chiral anomaly and the strong magnetic or vortical fields created in noncentral heavy-ion collisions can lead to various anomalous chiral effects in the quark–gluon plasma, including the chiral magnetic effect (CME), the chiral magnetic wave (CMW), and the chiral vortical effect (CVE). In this proceeding, recent ALICE measurements of these effects are summarized. Utilizing Event Shape Engineering, fractions of CME and CMW signals extracted in Pb–Pb collisions at √SNN = 5.02 TeV are consistent with zero within uncertainties. The CVE is studied using azimuthal correlations between baryon pair Λ–p with Λ–h and h–h as reference. These measurements provide new insights into the experimental search for anomalous chiral effects in heavy-ion collisions.