This work investigates the dynamical behavior of both the integer and fractional-order positron-acoustic solitary waves (PASWs) in a collisionless, unmagnetized electron-positron-ion plasma composed of stationary positive ions, inertial cold positrons, inertialess hot Maxwellian positrons, and inertialess electrons obeying a regularized κ-distribution (RKD). Using the reductive perturbation technique, we derive two planar evolutionary wave equations, known as, a quadratic nonlinearity Korteweg-de Vries (KdV) equation, valid away from critical plasma compositions, and a cubic modified KdV (mKdV) equation, which governs the dynamics at the critical composition where the quadratic nonlinearity vanishes. By checking the sign of the quadratic nonlinearity coefficient in the KdV equation, it is found that the current model supports both compressive (for a positive sign) and rarefactive (for a negative sign) PASWs. At the same time, the sign of the cubic nonlinear coefficient to the mKdV equation describes the propagation of solitary (for positive sign) or shock (for negative sign) structures. Within the Caputo fractional-derivative framework, we further construct the corresponding time-fractional KdV (FKdV) and fractional mKdV (FmKdV) equations and solve them analytically using the Tantawy technique, yielding rapidly convergent series approximations of fractional PASWs. The fractional order serves as a quantitative measure of memory, and its deviation from the integer limit modifies the temporal evolution, amplitude, and width of PASWs, mimicking non-Markovian transport and anomalous dissipation in the plasma. A systematic parametric study reveals how the RKD cutoff and superthermality indices, the hot-positron and ion concentrations, and the fractional order shape the profiles of both planar KdV- and mKdV-type PASWs. The excellent agreement between the fractional approximations and the known integer solutions, together with small absolute errors at successive orders, highlights the accuracy and efficiency of the Tantawy technique for fractional evolutionary wave equations. The present results are relevant to space and astrophysical plasmas where superthermal electron populations and multicomponent electron-positron-ion mixtures are expected.

In this work, the propagation of kinetic Alfvén solitary waves (KASWs) and kinetic Alfvén cnoidal waves (KACWs) is investigated in a strongly magnetized, low- β electron-ion plasma with ion pressure anisotropy and superthermal electrons, motivated by conditions in Saturn’s magnetospheric environment. Starting from a two-fluid description with a κ -distributed electron population and Chew-Goldberger-Low (CGL)-type ion pressure anisotropy, the reductive perturbation method is used to derive a planar Korteweg-de Vries (KdV) equation governing small-amplitude kinetic Alfvén structures. The model is then generalized to a time-fractional KdV equation by replacing the first-order temporal derivative with a Caputo fractional derivative to incorporate temporal nonlocality and memory effects in the plasma response. The resulting fractional evolution problem is treated using the Tantawy technique, which yields rapidly convergent analytical approximations for both fractional KASWs and fractional KACWs. The analysis shows that, for the low- β anisotropic conditions considered, only compressive kinetic Alfvén structures are supported in the sub-Alfvénic regime, and that superthermality, ion pressure anisotropy, plasma beta, and propagation obliqueness jointly control the amplitudes and widths of the solitary and cnoidal structures. Increasing the superthermal index reduces the deviation from Maxwellian behavior and produces stronger, broader compressive pulses, while larger ion pressure anisotropy and plasma beta mainly broaden the profiles with only minor changes in amplitude. The fractional order modulates the temporal development and localization of the nonlinear structures: reducing the order weakens the peak amplitude and slows the formation of sharp kinetic Alfvén fronts, reflecting the enhanced memory inherent to fractional dynamics. These results may assist in the interpretation of kinetic Alfvén activity in low- β space and astrophysical plasmas with ion pressure anisotropy and superthermal particles, such as Saturn’s magnetosphere and the near-Earth magnetosheath.

Building on our previous explorations of fractional KdV-solitary waves [Part (I)] ( El-Tantawy in Braz J Phys 55:123, 2025) and fractional modified KdV (mKdV)-solitary waves [Part (II)] (El-Tantawy in Braz J Phys 55:176, 2025), this research now explores the complex realm of fractional Gardner-solitary waves (FGSWs) in unmagnetized electronegative plasmas (ENPs) with nonthermal electrons. First, the reductive perturbation technique is applied to reduce the fluid model equations to the integer cubic-quadratic nonlinear Gardner/Extended KdV (EKdV) equation. This equation can describe the propagation of various nonlinear structures (e.g., solitary waves (SWs) and shock waves) in different plasma models and fluids, especially when the quadratic nonlinearity coefficient is close to zero. The second goal of the current study is to investigate the characteristics of fractional nonlinear structures that can arise and propagate in the current model. For this purpose, a novel technique, namely the Tantawy technique (TT), is applied to analyze the planar fractional EKdV (FEKdV) equation and model FEKdV-SWs. This approach produces accurate and stable analytical approximations. Additionally, the FEKdV equation is analyzed using the new iterative method (NIM) within the Laplace transform framework to compare its results with those of TT. To assess the accuracy of all generated approximations, the absolute error against the exact solution for the integer case is numerically estimated. Moreover, we numerically investigate the impact of different plasma parameters—negative ion concentration, ion mass ratio, and the fractional parameter—on the characteristic behavior of the FEKdV-SWs. This research provides important details about fractional nonlinear structures that can exist and propagate in laboratory, space, and astrophysical plasma systems.

The propagation of nonlinear electrostatic low-frequency ion-acoustic solitary waves (SWs) in an electron–positron–ion non-Maxwellian plasma with Cairns–Tsallis-distributed electrons and thermal positrons is examined in this work. The reductive perturbation technique (RPT) reduces the fluid model equations to the Korteweg–de Vries (KdV) equation family, including the planar KdV, modified KdV (mKdV), Kawahara, and modified Kawahara equations. Analysis of the present model’s polarity, based on the sign of the quadratic nonlinear term’s coefficient in the KdV equation, reveals the presence of both compressive and rarefactive nonlinear structures. This implies that, under specific plasma parameter values, the coefficient of the quadratic nonlinear term of the KdV equation will vanish. Therefore, we proceed to formulate an additional evolution equation with higher-order nonlinearity, known as the modified KdV (mKdV) equation, to characterize the nonlinear structures at specific critical values of the plasma parameters. Moreover, we investigate the results using the Kawahara and modified Kawahara equations, also known as the generalized fifth-order KdV and mKdV equations, as they can aid in reducing the discrepancy between the theoretical results of the KdV and mKdV equations and specific laboratory results or space observations. We analyze how the nonextensive parameter, nonthermal parameter (nonthermality), and positron concentration influence the properties of the SW structures. This research has potential applications in space and astrophysical plasma physics like interstellar plasma, stellar polytropes, and pulsar magnetosphere.

This study thoroughly examines the features of arbitrary amplitude ion-acoustic nonlinear structures, including both solitary and shock waves (double layers), in an unmagnetized electron–proton–ion plasma where electrons follow Cairns distributions and protons follow Maxwellian distributions. The Sagdeev pseudopotential (SP) approach is employed to reduce the fluid model equations into a pseudoenergy integral form that expresses potential energy as the SP. The SP is carefully analyzed to determine the precise conditions for the existence of both solitary and shock waves. Our detailed parametric analysis emphasizes the significant effect of electron nonthermality and proton concentration on the behavior, existence, and shape of ion-acoustic solitary and shock waves. This study provides important details about the complex, nonlinear wave phenomena in various space and astrophysical plasma environments, such as the solar wind, planetary magnetospheres, and ionospheres, where multicomponent plasmas with nonthermal particle distributions are common.

In this study, we examine large-amplitude ion-acoustic (IA) solitary waves (SWs) in unmagnetized, collisionless plasma. This plasma consists of inertial fluid ions, while non-Maxwellian positrons and electrons are noninertial. In our model, both positrons and electrons follow a κ -deformed Kaniadakis distribution. To analyze these large-amplitude IASWs, we reduce the fundamental equations to a single energy-balance-like equation using the Sagdeev pseudopotential (SP) approach. We also numerically discuss the conditions required for the existence of IASWs. Furthermore, we identify the regions where IASWs can occur based on key plasma parameters such as positron concentration, Mach number, temperature ratio, and the deformed parameter. We also examine how these parameters affect the Sagdeev potential and the soliton profile. This research is especially relevant to ongoing studies of generalized entropies in plasma physics.

The present investigation concerns the study of large-amplitude positron-acoustic solitary waves (PASWs) in four-component unmagnetized plasma exhibiting non-Maxwellian characteristics. The plasma model comprises cold inertial positrons, electrons described by a Cairns distribution, hot positrons governed by a Maxwellian distribution, and stationary ions. Sagdeev’s method is employed to derive the energy integral equation, which demonstrates the existence of both positive and negative polarity PASWs under appropriate plasma conditions. A comprehensive analysis is performed to determine the effect of various plasma parameters, including hot positron concentration, electron concentration, hot positron and electron temperature ratios, the Mach number, and the nonthermal parameter—which significantly influence the formation, amplitude, and width of these PASWs, as well as their existence regions. The findings suggest a possible association of these nonlinear structures with electrostatic perturbations observed in various laboratory plasmas and astrophysical environments, including the interstellar medium, pulsar magnetospheres, active galactic nuclei, and auroral acceleration regions.

In this neoteric study, the fractional and non-fractional electron-acoustic (EA) cnoidal waves (CWs) are investigated in an unmagnetized homogeneous non-Maxwellian plasma composed of hot nonthermal electrons following Cairns distribution, cold electrons, and immobile positive ions. To do this, an evolution wave equation (Korteweg-de Vries (KdV) equation) that governs the propagation of these waves in the current model is generated by using the reductive perturbation technique. Analysis of the KdV equation’s nonlinearity coefficient, which dictates the polarity of nonlinear waves that may emerge and propagate in the current model, reveals that this model only supports rarefactive waves. The impact of various plasma parameters, like the nonthermal parameter and the density ratio of hot-to-cold electrons (hot electron concentration), on the essential features of the EACWs is numerically examined. The second objective of this investigation is to explore the fractional-order parameter’s effect on the dynamics of periodic wave propagation within the current model. This is achieved by transforming the non-fractional planar KdV equation into its fractional counterpart and analyzing it using contemporary methods, such as the Tantawy technique, which has proven its efficacy and precision in numerous prior studies.

The propagation of high-frequency positron-acoustic cnoidal waves (PACWs) is investigated in four-component plasmas consisting of inertialess non-Maxwellian electrons and hot positrons adhering to the Kaniadakis distribution, together with inertial fluid cold positrons and stationary ions. Using the reductive perturbation approach (RPA), the quadratic planar Korteweg-de Vries (KdV) equation is derived, and its cnoidal wave (CW) solution is reported. Additionally, at a critical plasma composition, such as the hot positron concentration, the modified-KdV (mKdV) equation is derived, and its CW solution is investigated. Subsequently, to examine the distinctive behavior of the fractional PACWs, both the integer KdV and mKdV equations are transformed into their fractional counterparts, namely the fractional KdV (FKdV) and fractional mKdV (FmKdV) equations. The Laplace novel iterative method (LNIM) is utilized to solve both FKdV and FmKdV equations and derive high-accuracy approximations for the two equations for modeling the characteristic behavior of FKdV-PACWs and KmKdV-PACWs. The influence of several associated physical parameters on the profile (amplitude and width) of both KdV-PACWs and mKdV-PACWs is numerically examined. Additionally, the impact of the fractionality on the profile of both FKdV-PACWs and FmKdV-PACWs is investigated. Moreover, the absolute error of the derived approximations is estimated and discussed numerically. Furthermore, the potential applications of the current study are discussed, and the obtained results are valuable for investigating the cosmic ray spectrum and the plasma environment surrounding stars.

This study investigates the propagation of both fractional and non-fractional ion-acoustic cnoidal waves (IACWs) in a magnetized degenerate Thomas-Fermi electron-positron-ion ( e − p − i ) plasma, incorporating the effects of magnetic fields on wave dynamics. Using the reductive perturbation method (RPM), the planar integer Korteweg-de Vries (KdV) equation is derived, accounting for the influence of the magnetic field on nonlinear wave structures. The analysis reveals the existence of positive potential (compressive) cnoidal waves, which, in the limiting case, reduce to solitary waves. The characteristics of these waves, which demonstrate how the electron-to-positron Fermi temperature ratio, positron concentration, and obliqueness affect their profile. The study’s findings are relevant to astrophysical environments and dense plasmas generated in laser-produced plasmas. For the second objective of this investigation, the integer planar KdV equation is converted to the planar fractional KdV equation (FKdV) using a suitable transformation to study the impact of the fractional order parameter on the fractional IACW profile. To this end, the planar FKdV equation is solved using the Tantawy technique and the Laplace residual power series method (LRPSM). Some approximate analytical solutions to the planar FKdV equation are derived using the two proposed approaches. The generated approximations are numerically examined and compared with the exact solution for the integer case to assess the accuracy of the derived approximations. Numerical results are constructed based on parameters relevant to dense astrophysical environments, such as white dwarfs, highlighting the significant role of the magnetic field in modifying wave behavior.

The present study investigates the coexistence of arbitrary amplitude positive and negative potential ion-acoustic solitary waves (IASWs) in an unmagnetized electronegative plasma comprising inertial cold ions and inertialess electrons exhibiting a Cairns–Tsallis distribution. The fluid model equations are reduced to an energy balance equation using Sagdeev’s approach. The Sagdeev potential is analyzed based on the criteria for the existence of solitary waves. The existence regions for the ion-acoustic waves (IAWs) are precisely determined based on the related physical parameters. The current model supports both compressive and rarefactive IAWs. This study demonstrates the significant influence of related physical parameters, such as the negative density ratio, nonextensive parameter, and nonthermal parameter, on the IASWs behavior. The present study is significant in understanding the nonlinear structures dynamics observed in the lower part of the magnetosphere and the upper part of the ionosphere through various satellite missions.

This study examines the propagation of nonlinear structures in a magnetized, homogeneous plasma model with cold electrons, stationary ions, and nonthermal electrons characterized by a Cairns distribution. The electron-acoustic cnoidal waves (EACWs) in this plasma model are investigated. The reductive perturbation method (RPM) is used to derive the Korteweg–de Vries (KdV) equation. In the form of a cnoidal wave (CW), the solution to the KdV equation is derived. Various plasma parameters, including the concentration of hot electrons, the nonthermal parameter, obliqueness, and the magnetic field, determine the key features of EACWs. In the limiting case, the CW structure can be reduced to a solitary wave (SW) structure. The dispersion and nonlinear coefficients require consideration. We also seek to uncover the connection between the coefficients and these plasma properties, as well as the Sagdeev potential. High-energy electrons are essential for the formation of negative polarity structures. The current plasma model supports rarefactive types of SW and CW.

The study explores the nonlinear dynamics of a magnetized plasma system characterized by two types of electrons following a Cairns distribution, alongside warm ions and an electron beam. By employing the reductive perturbation technique (RPT), the governing nonlinear differential equation for this system has been established. The presence of the electron beam emerges as a distinctive factor that significantly influences wave propagation within the plasma environment. Findings indicate that soliton waves traversing this plasma medium undergo alterations in their amplitude, phase velocity, and nonlinear coefficient due to the electron beam’s influence. Furthermore, the results suggest that the electron number density of the beam can be manipulated to control the propagation of ion acoustic wave (IAWs) in plasmas, highlighting potential applications in plasma-laser interactions.

study investigates ion-acoustic (IA) solitary waves (SWs) in a magnetized plasma composed of positive ions and two electron populations following the Cairns distribution. Using the reductive perturbation technique (RPT), we derive and solve a nonlinear Korteweg-de Vries (KdV) equation to analyze the characteristics of these waves. Our findings reveal that the system can support both compressive (positive) and rarefactive (negative) potential solitons. The wave's amplitude, width, and existence are significantly influenced by plasma parameters, including the cold-to-hot electron temperature ratio (sigma), the cold electron-to-ion density ratio (f), and the cold electrons nonthermality parameter (beta c). We also demonstrate that the strength of the external magnetic field (Omega) and obliqueness (theta) plays a crucial role in determining the wave's characteristics. These results are relevant for understanding electrostatic wave structures observed in astrophysical environments like Saturn's magnetosphere.

This work investigates the characteristics of nonlinear ion-acoustic solitary waves (IASWs) that arise and propagate within a nonmagnetized plasma composed of inertial ions, an electron beam, and inertialess Cairns-distributed electrons. To accomplish the primary objective of this study, the two-fluid model is integrated with the reductive perturbation technique (RPT) to derive the evolutionary wave equations applicable for modeling both non-fractional and fractional IASWs in the present plasma model. Utilizing this process, the integer-order Korteweg-de Vries (KdV) equation is derived, followed by analyzing its solitary wave solution. For the second objective of this investigation, a novel method known as the “Tantawy technique” is employed to analyze the fractional KdV equation, aiming to produce highly accurate and more stable approximations suitable for effectively representing physical phenomena. The inquiry then examines the impact of several physical elements, including the nonthermal parameter, electron beam velocity, electron beam concentration, and fractional parameter, on the existence region of solitary waves (SWs) and, consequently, on the properties of IASWs. The Cairns distribution of electrons significantly influences the characteristics of IASWs, depending on parameter that governs the distribution, particularly the nonthermality of inertialess electrons. The research examines the distinct properties of SWs and their existence domain concerning relevant plasma parameters.

this study, the characteristic of nonlinear cnoidal waves in collisionless, nonmagnetic, and homogeneous plasma comprising cold inertial electrons, inertialess hot nonextensive q-distributed electrons, and stationary background ions are reported. The reductive perturbation approach is employed with the aim of deriving the evolution equation in the form of the Kortewegde Vries equation. Subsequently, the cnoidal wave solution of the Korteweg-de Vries equation is obtained. In the limiting case, this solution reduces to the solitary wave (soliton) solution. The influence of key plasma parameters specifically, the hot-to-cold electron density ratio alpha and the nonextensivity parameter q on the characteristics of electron-acoustic cnoidal waves is systematically investigated. This analysis provides valuable physical insights into the role of nonequilibrium statistics in wave propagation. Our findings are relevant to understanding wave phenomena in various space and astrophysical environments characterized by nonextensive electron populations, providing a theoretical foundation for the interpretation of observational data. Copyright c 2025 EPLA All rights, including for text and data mining, AI training, and similar technologies, are reserved.

Electrical impulse voltage discharges using hydrogen peroxide (H2O2) are of increasing interest for eradicating biological species. Pulsed power is beneficial in addressing the problem of overheating the cathode surface due to successive collisions of energetic plasma species. The present study demonstrates the generation of active species of oxygen (O, O-, and O2), hydrogen (H-α, H-β), and hydroxyl radicals (OH−) in pulsed hydrogen peroxide discharge. The level of active species is directly or indirectly related to the emission intensity by varying the applied current and filling pressure. The discharge is generated between two annular electrodes powered by a 50-Hz pulsed direct current source. The aqueous hydrogen peroxide solution is sucked into the stainless steel reactor by creating a pressure gradient. The experiment is carried out for different discharge currents (0.2–0.5 A) and filling pressures (0.1–0.5 mbar). Optical emission spectroscopy (OES) is performed using McPherson (0.01 nm) and Ocean (0.75 nm) spectrometers to record spectra. Following the optimal discharge conditions, Pseudomonas aeruginosa samples (N × 104 CFU/0.1 ml per sheet) are treated at a filling pressure of 0.5 mbar and a current density of 2.2 mA/cm2 for different treatment times. Inactivation is achieved by counting the viable number of colonies before and after plasma treatment using the serial dilution method. Scanning electron microscopy (SEM) was accomplished for Pseudomonas aeruginosa, which confirms the inactivation of the pathogens.

This study aims to examine the properties of the nonplanar (cylindrical and spherical) ion-acoustic solitary waves (SWs) and cnoidal waves (CWs) in a collisionless, unmagnetized electron-ion (EI) plasma having a Cairns–Tsallis distribution for the electrons. This study is structured around two main lines. The first trend involves deriving the nonplanar Korteweg-de Vries (KdV) equation by utilizing the method of reductive perturbation (MRP). This equation describes small-amplitude (non)planar acoustic waves (AWs). Furthermore, the nonplanar Kawahara equation (KE) is formulated to examine the significant magnitude of planar and nonplanar SWs and CWs. The current plasma model supports compressive and rarefactive IA solitary and cnoidal structures, depending upon the associated physical factors such as the nonextensive parameter (nonextensivity) and nonthermal parameter (nonthermality). When the plasma compositions reach some critical values, such as the critical value of nonthermality, the coefficient of the quadratic nonlinear term vanishes. Hence, both nonplanar modified KdV (mKdV) equation and modified KE (mKE) with cubic nonlinearity are derived to accurately depict the dynamics of both small and large amplitudes of nonplanar SWs and CWs and any other structures related to this family of evolution equations. The influences of the nonextensivity and nonthermality on the profile of (non)planar KdV soliton and the (non)planar Kawahara SWs and CWs are numerically examined using some semi-analytical and numerical approximations. Also, the impact of the nonextensivity on the profile of (non)planar mKdV soliton and the (non)planar modified Kawahara SWs and CWs is reported. It is tracked down that the variety of different plasma parameters significantly alters the characteristic properties of the small and large amplitude ion-acoustic waves (IAWs) discussed by the nonplanar KdV-type equations.

The main objective of this work is to investigate the characteristics and behavior of the ion-acoustic cnoidal waves (IACWs) in an electron–positron–ion magnetoplasma having inertial positive ions with anisotropic thermal pressure and inertialess Maxwellian positrons and electrons. We utilize the reductive perturbation technique to reduce the fluid governing equations of the present model into the Korteweg–de Vries (KdV) equation in order to achieve this objective. We calculate the periodic solution of the KdV equation, also referred to as the cnoidal wave. We investigate the impact of various related parameters, including ion pressure anisotropy, positron concentrations, and temperature ratio, on the properties of IACWs. This study, particularly in the near-Earth magnetosheath and magnetosphere, may offer an insightful analysis of space and astrophysical plasma systems displaying ion pressure anisotropy.

This study investigates the arbitrary amplitude high-frequency electron-acoustic (EA) solitary waves (EASWs) in a multi-component magnetoplasma consisting of inertial fluid cold electrons and inertialess Kaniadakis distributed hot electrons and stationary positive ions. The Sagdeev potential approach is implemented to derive the energy-balance equation governing arbitrary amplitude EASWs’ dynamics. On examining the condition responsible for determining the polarity of the waves, it was discovered that the existing model exclusively allows for the existence of negative (rarefactive) EASWs. The influence of critical factors, such as Mach number, the direction of propagation, the strength of the magnetic field, and the κ-deformed parameter on the profile of the EASWs is examined and discussed. We will also determine whether shock waves can exist and propagate in this model or not after checking all the criteria for their existence.