Isothermal Electrons Research Articles

An intriguing numerical strategy for Zakharov–Kuznetsov equation through graph-theoretic polynomials

This paper explores graph-theoretic polynomials to find the approximate solution of the (2+1)D Time-fractional Zakharov-Kuznetsov(TF-Z-K) equation. The Zakharov-Kuznetsov equations govern the behavior of nonlinear acoustic waves in the plasma of hot isothermal electrons and cold ions in the presence of a homogeneous magnetic field. Independence polynomials of the Ladder-Rung graph serve as the polynomial approximation for the suggested Independence Polynomial Collocation Method (IPCM). The Caputo fractional derivatives are adopted to determine the fractional derivatives in the TF-Z-K equation. The TF-Z-K equation is converted into a system of nonlinear algebraic equations using the collocation points in IPCM. The Newton-Raphson approach yields the solution of the suggested method by solving the resulting system. We’ve compared a few scenarios with the tangible outcomes to validate the procedure. Quantitative outcomes match the current findings and validate the exactness of IPCM compared t o the recent numerical and semi-analytical approaches in the literature.

Synergetic impact of volcanic ash and calcium carbide residue on the properties and microstructure of cementitious composites

The synergetic impact of using volcanic ash (VA) and calcium carbide residue (CCR) on the engineering properties of cementitious mortar was assessed. Cement was replaced with VA at 0–40 % by mass and/or CCR at 0–20 % by mass. Blended mortars were tested for flow, setting time, compressive strength, and ultrasonic pulse velocity (UPV). The flow increased when using VA but decreased with the inclusion of CCR. Compared to the cement-based control mix, ternary mixes had a lesser flow. The impact of VA replacement on the initial and final setting times was marginal until a substitution rate of 40 %, after which the setting times were prolonged. Similarly, the setting time was extended with CCR replacement. The compressive strength and UPV improved with the use of 10–20 % VA and/or 5 % CCR for binary and ternary mortar mixes, with the highest strength of 55.4 MPa and UPV of 4490 m/s being recorded for the mix comprising 20 % VA and 5 % CCR. Mixes were further analyzed through isothermal calorimetry, X-ray diffraction, and scanning electron microscopy. The cumulative heat generation was reduced for binary and ternary mixes except for those containing 20 % VA only. The microstructure analysis highlighted the formation of C-S-H and C-A-S-H as reaction products and the consumption of Ca(OH)2. This study provides novel insights into optimal combinations of VA and CCR for superior mortar performance, offering practical approaches to reducing cement content and lowering carbon emissions without compromising performance.

Phosphoric acid-activated metakaolin-based geopolymer: Optimizing P/A molar ratio to solidify Cs+ and Sr2+ in nuclear waste

Phosphoric Acid-activated Metakaolin-based Geopolymer (PAMG) is an efficient solidified material. This paper reports the effect of the H3PO4 to Al2O3 (P/A) molar ratio on the hydration, phase assemblage, morphology, and compressive strength of PAMG and the solidification of simulated radionuclides Sr and Cs by PAMG. The hydration behavior and microstructure of PAMG were investigated using isothermal calorimetry, X-ray diffraction (XRD), and scanning electron microscope (SEM). The impacts of Cs and Sr on the leaching behavior and microstructure of PAMG were assessed using atomic absorption spectrum (AAS), SEM, and energy dispersion spectrum (EDS). The results indicate that the compressive strength of PAMG increases and then decreases as the P/A ratio increases. The highest compressive strength reaching 98.1 MPa after 28 days of curing, was observed at a P/A molar ratio of 1.8. The addition of Cs and Sr resulted in a decrease in the compressive strength of PAMG, with Sr showing a more significant reduction in PAMG's compressive strength. However, PAMG still exhibited a high efficiency in solidifying simulated nuclides Cs and Sr, with 42 days leaching rates of 3.7 × 10−5 cm/d and 5.0 × 10−6 cm/d, respectively. These results indicate the huge potential of PAMG in solidifying nuclides.

Axisymmetric hybrid Vlasov equilibria with applications to tokamak plasmas

We derive axisymmetric equilibrium equations in the context of the hybrid Vlasov model with kinetic ions and massless fluid electrons, assuming isothermal electrons and deformed Maxwellian distribution functions for the kinetic ions. The equilibrium system comprises a Grad–Shafranov partial differential equation and an integral equation. These equations can be utilized to calculate the equilibrium magnetic field and ion distribution function, respectively, for given particle density or given ion and electron toroidal current density profiles. The resulting solutions describe states characterized by toroidal plasma rotation and toroidal electric current density. Additionally, due to the presence of fluid electrons, these equilibria also exhibit a poloidal current density component. This is in contrast to the fully kinetic Vlasov model, where axisymmetric Jeans equilibria can only accommodate toroidal currents and flows, given the absence of a third integral of the microscopic motion.

Ba6RE2Ti4O17 (RE = Nd, Sm, Gd, Dy-Yb): A Family of Rare-Earth-Based Layered Triangular Lattice Magnets.

The exploration of new rare-earth (RE)-based triangular-lattice materials plays a significant role in motivating the discovery of exotic magnetic states. Herein, we report a family of hexagonal perovskite compounds Ba6RE2Ti4O17 (RE = Nd, Sm, Gd, Dy-Yb) with a space group of P63/mmc, where magnetic RE3+ ions are distributed on the parallel triangular-lattice layers within the ab-plane and stacked in an 'AA'-type fashion along the c-axis. The low-temperature magnetic characterizations indicate that all synthesized Ba6RE2Ti4O17 compounds exhibit dominant antiferromagnetic (AFM) interactions and the absence of magnetic order down to 1.8 K. The isothermal magnetization and electron spin resonance results reveal the distinct magnetic anisotropy for the compounds with different RE ions. Moreover, the as-grown Ba6Nd2Ti4O17 single crystals exhibit Ising-like magnetic anisotropy with a magnetic easy-axis perpendicular to the triangle-lattice plane and no long-range magnetic order down to 80 mK, as the quantum spin liquid candidate with dominant Ising-type interactions.

On the propagation of dust-acoustic dressed solitons (DADS) influenced by dust concentration and hot isothermal electrons in an inhomogeneous plasma

On the propagation of dust-acoustic dressed solitons (DADS) influenced by dust concentration and hot isothermal electrons in an inhomogeneous plasma

Modulated dust-ion-acoustic waves result from Earth's magnetosphere and lunar ionosphere interactions

The Earth's magnetosphere's modulational amplitude dust-ion-acoustic waves are studied. When the moon passes through the Earth's magnetotail, its dust grains may interact, causing these waves. The theoretical plasma model for this study includes positive ionospheric ion fluids, isothermal electrons, and fluid-negative dust grains on the moon. A perturbation technique derived the nonlinear Schrödinger equation, which exhibited dispersion and nonlinear effects. The nonlinear and dispersion term coefficients' polarity may predict stable and unstable pulse domains. A numerical study was performed to identify unstable pulse domains and their connections with bright and rogue unstable modes. The effects of critical plasma conditions on these pulses' basic features have been studied. This study showed that increasing the ratio of ions to electrons temperature and density reduces system nonlinearity. Consequently, shorter unstable pulses are formed. Amplification of plasma unstable waves results in an increase in their intensity and energy, potentially impacting any device traveling through the area of impact.

Co-treatment of steel slag and oil shale waste in cemented paste backfill: Evaluation of fresh properties, microstructure, and heavy metals immobilization

The environmentally sustainable treatment of steel slag (SS) and oil shale waste (OSW) is a significant concern in the field of industrial development. The mining industry also faces challenges related to the high costs and carbon emissions associated with ordinary Portland cement (OPC), leading to environmental pollution. To address these challenges, this study aimed to develop a cost-effective and environmentally friendly binder for cemented paste backfill (CPB) by utilizing SS and calcined oil shale waste (COSW) as primary precursors. Extensive investigations were conducted to evaluate the properties of the CPB sample with varying COSW content, including rheological properties, mechanical strength, and microstructure. The binder sample was comprehensively characterized using isothermal calorimetric analysis, X-ray diffraction (XRD), thermogravimetry (TG), and scanning electron microscopy (SEM). Based on systematic experimentation, an optimal blend ratio for the binder was determined, consisting of 60 wt% SS, 15 wt% COSW, 15 wt% phosphogypsum (PG), and 10 wt% OPC. The exceptional performance of the binder was attributed to the substantial formation of precipitated ettringite (AFt), resulting in a more compact structure and improved mechanical strength. Additionally, a sequential extraction test revealed that the heavy metals in the CPB sample were mainly present in the residual fraction, demonstrating the effective immobilization of heavy metals by the binder.

Linear and nonlinear kinetic Alfvén waves at Venus

Space observations show that Venus suffers significant atmospheric erosion caused by the solar wind forcing. Plasma acceleration is found to be one of the main mechanisms contributing to the global atmospheric loss at Venus through its magnetotail. Motivated by these observations, we propose that kinetic Alfvén waves (KAW) may be a possible candidate for charged particle energization at the upper atmosphere of Venus. To test this hypothesis, we explored the basic features of both linear and nonlinear KAW structures at Venus. We considered a low-but-finite β plasma consisting of ionospheric populations (consisting of hydrogen H+, oxygen O−, and isothermal ionospheric electrons) and solar wind populations (protons and isothermal electrons). In the linear regime, we obtain a linear dispersion relation that exhibits a dependence on the intrinsic plasma configuration at Venus. The linear analysis predicts wave structures with wavelengths of ~10–102 km and frequencies of up to ~5 Hz. In the nonlinear regime, small-but-finite-amplitude solitary excitations with their corresponding bipolar electric field are obtained through the reductive perturbation technique. We discuss the influence of the intrinsic plasma parameters (the ionic concentration, solar wind electron temperature, magnetic field strength, and obliqueness) on the nature of the structures of the solitary KAWs and their corresponding electric field. We find that the ambipolar field is amplified with increasing propagation angle, magnetic field strength, and relative temperature of electrons. Our theoretical analysis predicts the propagation of elliptically polarized ultra-low-frequency (ULF) solitary structures with a maximum magnitude of ~0.01–0.034 mV m−1 and a time duration of 20–30 s. The result of the fast Fourier transform (FFT) power spectra of the ambipolar parallel electric field is broadband electromagnetic noise in the frequency range of ~0.5–2 Hz.

Investigating the parametric impacts on dust-ion-acoustic solitary waves in magnetized rotating plasmas

This article examines the combined effect of plasma rotation, magnetic field, and several parameters on the dust-ion-acoustic solitary waves (DIASWs). A rotating plasma system is assumed that comprises positive ions (mobile and adiabatic), negative light ions (trapped), isothermal electrons, and dust particles (stationary and positively or negatively charged). Using the reductive perturbation technique (RPT), the mKdV equation is obtained to investigate the variations in wave nature caused by different forces and parameters. It is found that the external magnetic field, oblique rotation, electron and dust concentrations play a key role in varying wave amplitude, width as well as phase speed. Depending on whether the dust is positively or negatively charged, the rotational frequency increases (decreases) the phase speed (amplitude and width). Moreover, the magnetic field enhances the wave amplitude but reduces the width. The results obtained from the study are expected to be useful in describing rotating flows of magnetized plasmas observed in white dwarfs, neutron stars, pulsar radiations, etc.

A Fractional Analysis of Zakharov–Kuznetsov Equations with the Liouville–Caputo Operator

In this study, we used two unique approaches, namely the Yang transform decomposition method (YTDM) and the homotopy perturbation transform method (HPTM), to derive approximate analytical solutions for nonlinear time-fractional Zakharov–Kuznetsov equations (ZKEs). This framework demonstrated the behavior of weakly nonlinear ion-acoustic waves in plasma containing cold ions and hot isothermal electrons in the presence of a uniform magnetic flux. The density fraction and obliqueness of two compressive and rarefactive potentials are depicted. In the Liouville–Caputo sense, the fractional derivative is described. In these procedures, we first used the Yang transform to simplify the problems and then applied the decomposition and perturbation methods to obtain comprehensive results for the problems. The results of these methods also made clear the connections between the precise solutions to the issues under study. Illustrations of the reliability of the proposed techniques are provided. The results are clarified through graphs and tables. The reliability of the proposed procedures is demonstrated by illustrative examples. The proposed approaches are attractive, though these easy approaches may be time-consuming for solving diverse nonlinear fractional-order partial differential equations.

Electron heating in kinetic-Alfvén-wave turbulence.

We report analytical and numerical investigations of subion-scale turbulence in low-beta plasmas using a rigorous reduced kinetic model. We show that efficient electron heating occurs and is primarily due to Landau damping of kinetic Alfvén waves, as opposed to Ohmic dissipation. This collisionless damping is facilitated by the local weakening of advective nonlinearities and the ensuing unimpeded phase mixing near intermittent current sheets, where free energy concentrates. The linearly damped energy of electromagnetic fluctuations at each scale explains the steepening of their energy spectrum with respect to a fluid model where such damping is excluded (i.e., a model that imposes an isothermal electron closure). The use of a Hermite polynomial representation to express the velocity-space dependence of the electron distribution function enables us to obtain an analytical, lowest-order solution for the Hermite moments of the distribution, which is borne out by numerical simulations.

Microstructure development of slag activated with sodium silicate solution: Experimental characterization and thermodynamic modeling

Slag is a by-product of the steel industry that can be used as a binder with alkali solutions. In this study, the microstructural development is discussed for two alkali-activated slag mixes with promising properties for structural applications. The reaction products for both mixes were characterized by X-ray diffraction, thermogravimetry, Fourier-transform infrared spectroscopy and nuclear magnetic resonance. The Ca/Si ratio of C-A-S-H gel and the secondary products such as hydrotalcite, M-S-H and zeolites depend on the activator solution. The dissolution kinetics is followed by isothermal calorimetry and scanning electron microscopy. Calorimetry data can be adjusted with the maximum heat release obtained from thermodynamic modeling to predict the degree of dissolution. Thermodynamic modeling using the Pitzer ion activity model was applied for alkali-activated slag. This model is relevant for the first two days of reaction. For later age, the extended Debye–Hückel ion activity model and the Pitzer ion activity model give identical results. Phase assemblage predicted using thermodynamic modeling with the correct CASH model and consistent M-S-H and zeolite datasets agreed well with experiments.

Role of solar wind on the ionic escaping from Venus upper ionosphere via plasma wakefield

According to the observations that detected significant ionospheric escape from Venus, a test charge approach is suggested to explain the ionic loss caused by the solar wind (SW) interaction with the Venusian upper ionosphere. The proposed plasma system consists of two positive planetary ions (H + and O +) with isothermal electrons and streaming SW protons, with Maxwellian electrons. The electrostatic Debye screening and wakefield potentials caused by a moving test charge as well as the modified dielectric constant of the ion-acoustic waves (IAWs) created in the model are derived. The normalized Debye potential is found to decrease exponentially with the axial distance. Whereas the amplitude of the wakefield potential is amplified with the altitudes and decreases with increasing the density of either planetary oxygen or the SW protons but it is enhanced by SW electrons number density. However, the wakefield amplitude is not affected by the SW protons velocity or their temperatures because the SW protons velocity is fast compared with the velocity of the plasma system. Thus, the properties of the ions escaping are affected by the velocity variations within a certain range called the velocity scale window. The obtained results are found to be in a good agreement with the observed data.

Solitary Wave Solutions of the Fractional-Stochastic Quantum Zakharov–Kuznetsov Equation Arises in Quantum Magneto Plasma

In this paper, we consider the (3 + 1)-dimensional fractional-stochastic quantum Zakharov–Kuznetsov equation (FSQZKE) with M-truncated derivative. To find novel trigonometric, hyperbolic, elliptic, and rational fractional solutions, two techniques are used: the Jacobi elliptic function approach and the modified F-expansion method. We also expand on a few earlier findings. The extended quantum Zakharov–Kuznetsov has practical applications in dealing with quantum electronpositron–ion magnetoplasmas, warm ions, and hot isothermal electrons in the presence of uniform magnetic fields, which makes the solutions obtained useful in analyzing a number of intriguing physical phenomena. We plot our data in MATLAB and display various 3D and 2D graphical representations to explain how the stochastic term and fractional derivative influence the exact solutions of the FSEQZKE.

W-shaped soliton solutions to the modified Zakharov-Kuznetsov equation of ion-acoustic waves in (3+1)-dimensions arise in a magnetized plasma

<abstract><p>This paper is presented to investigate the exact solutions to the modified Zakharov-Kuznetsov equation that have a critical role to play in mathematical physics. The $ \tan \left(\phi \left(\zeta \right)/2 \right) $-expansion, $ (m+G'(\zeta)/G(\zeta)) $-expansion and He exponential function methods are used to reveal various analytical solutions of the model. The equation regulates the treatment of weakly nonlinear ion-acoustic waves in a plasma consisting of cold ions and hot isothermal electrons throughout the existence of a uniform magnetic field. Solutions in forms of W-shaped, singular, periodic-bright and bright are constructed.</p></abstract>

Dynamic mechanical behavior, microstructure evolution, and restoration mechanism of a β‐Ti alloy during hot compression deformation

AbstractMetastable β titanium alloys are promising materials for lightweight and energy‐efficient applications due to their high strength and low density. Thermal–mechanical processing (TMP) is one of the most effective ways to improve the mechanical properties of such alloys. This paper describes a systematic TMP investigation on a new metastable β titanium alloy, including its dynamic mechanical behavior, and microstructure evolution, via isothermal compression tests and electron back‐scattered diffraction characterizations. The results show that the compression stress increases with an increase in the strain rate and a decrease in the temperature. After yielding, the compression stress–strain pattern shows flow‐softening behavior at a low temperature and a high strain rate, while sustaining a steady flow state at a high temperature and a low strain rate. The temperature‐rise effect contributes to a large degree of flow softening at high strain rates. After the correction for temperature rise, the stress–strain constitutive relationships are established, showing that the compression behavior varies in different phase regions. Based on the microstructure characterizations, it is found that the dynamic recovery and dynamic recrystallization dominate the hot deformations in β phase region and at low strain rates, while the deformation band as an additional product is found in α + β phase region and at high strain rates. The results contribute to a better understanding of the TMP for the considered alloy and may also represent a useful database for β‐Ti alloy applications in lightweight mechanical systems.

Propagation of different kinds of non-linear ion-acoustic waves in Earth’s magnetosphere

The non-linear propagation of different kinds of ion-acoustic waves (IAWs) in multi-component plasma involving proton beam, positive ions and isothermal electrons has been studied. Using the derivative expansion method of basic equations, namely the hydrodynamic and Poisson equations, they are reduced to a single evolution equation of the non-linear Schrödinger (NLS)-type equation. By applying this model to plasma formed in Earth’s magnetosphere, different waves can be predicted that express the properties of the plasma. Using the separating variables method and the \(G^{{\prime}}/G\)-expansion method, we derived the exact analytical solutions to the evolution equation by using different solution regions in which non-linear waves are defined. A comparison has been made between the solutions describing the differential equation in each region in which the solution can appear using the data on the Earth’s magnetosphere in the study by Alotaibi et al. (2021).

Effect of the solar wind on the nature of arbitrary amplitude ion-acoustic solitary waves in Venus’ upper ionosphere

ABSTRACT Observations suggest that at altitudes of 1000–2000 km the interaction between the solar wind and Venus’ ionospheric plasma leads to ion-acoustic waves (IAWs) formation. For studying this hypothesis, a suitable hydrodynamic model relying on the observational data from Pioneer Venus Orbiter (PVO) and Venus Express (VEX) is developed. It consists of two ionospheric fluids of positive ions, hydrogen (H+), and oxygen (O+), and isothermal ionospheric electrons interacting with streaming solar wind protons and isothermal solar wind electrons. The favourable conditions and propagation characteristics of the fully non-linear IAWs along with their dependence on solar wind parameters are examined and compared with the available space observations. It is found that the pulse amplitude is decreased by increasing the temperature of either the solar wind protons or electrons. In contrast, a higher relative density or velocity of the solar wind protons amplifies the amplitude of the solitary structures. Moreover, only velocity variations within a certain range called the plasma velocity scale can affect the basic features of the solitary pulses. Beyond this scale, solitary waves are not affected by the solar wind protons’ velocity anymore. This theoretical model predicts the propagation of electrostatic solitary waves with a maximum electric field of 7.5 mV m−1 and a pulse time duration of 3 ms. The output of the fast Fourier transformation (FFT) power spectra of the electric field pulse is a broad-band electrostatic noise in a frequency range of ∼0.1–4 kHz. These FFT calculations are in good agreement with PVO’s observations.

Type-B Energy Process: Asymmetric Function-Gated Isothermal Electricity Production

Recently, we identified two types (A and B) of energy processes that naturally occur on Earth. Type-A energetic process such as the classical heat engines follows well the thermodynamic second law; Type-B energy process follows the first law of thermodynamics, but does not have to be constrained by the second law, owning to its special asymmetric function. The identification of type-B process inspired a novel invention on isothermal electricity production through an asymmetric function-gated power generation system. This article highlights the fundamental embodiments, scientific principles, and physics equations for the asymmetric function-gated isothermal electricity generator that comprises an exceptionally low electron-work-function surface as an isothermal electron emitter and a space gap that permits the isothermally emitted electrons to travel ballistically to a collector. The physics equations for the density of isothermal electricity current, voltage and power all clearly show that the type-B energy technology can isothermally utilize the limitless environmental heat energy to generate electricity power as long as the electron-work function of the emitter WFe is substantially lower than that of the collector WFc. It has the potential capability to forever energize many electronic devices such as mobile phones and laptops, which is of great scientific and practical importance.