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In 1980, Prof. Bimla Buti derived, for the first time, an exact solution for localized nonlinear ion-acoustic waves in a plasma with two electron components. Her theory predicted that in the presence of a second electron component, ion-acoustic holes (i.e., solitons with density dips) can exist in addition to regular ion-acoustic solitons having density humps. In 1982, Temerin, et al. [1] reported the observations of ion holes in the Earth's auroral acceleration region between 6000 and 8000 km altitude by S3-3 spacecraft, thus confirming the theoretical predictions of Buti's model. Later on, ion holes were observed on auroral field lines by the Viking spacecraft [2,3] and the Polar spacecraft [4]. It is indeed a nice example where theory leads space experiments and observations. [ABSTRACT FROM AUTHOR]

In recent years, it has been found that magnetic dip caused by diamagnetic motion of injected plasma can provide an appropriate environment for excitation of electromagnetic ion cyclotron (EMIC) waves. These findings have been widely reported in the Earth's magnetic environment. However, it has rarely been reported in Jupiter's magnetic environment. This paper reports the characteristics of EMIC waves observed by Juno in the magnetic dip of Jupiter. Multiple‐band EMIC waves are observed in frequency range from 10−3 Hz to several Hz. The theoretical analysis shows that in this event both He+ band and O+ band EMIC waves can be constrained in the magnetic dip, which is consistent with the wave emissions observed inside the magnetic dip. Our result provides the first evidence that EMIC wave can be ducted inside a magnetic dip in Jupiter's magnetosphere. Plain Language Summary: The relationship between magnetic structures and electromagnetic waves in the Earth's magnetosphere has been widely reported. Recent studies have theoretically displayed the effects of the magnetic dip on the EMIC wave propagation in Earth's magnetic field. In this paper, we use the event observed by Juno in the magnetic environment of Jupiter to analyze the effect of the magnetic dip on the propagation of EMIC waves. As a result, the observed EMIC waves can be ducted inside the magnetic dip of Jupiter's magnetosphere. Since these ducted waves would influence the dynamics of energetic protons through longtime scattering effects, the magnetic dip is expected to play an important role in the dynamics of Jupiter's magnetosphere. Key Points: Electromagnetic ion cyclotron (EMIC) waves are observed during the magnetic dip by JunoTheoretical analysis about the effects of magnetic dips on the EMIC wave propagation in Jupiter's magnetosphere is performedBoth He+ and O+ band EMIC waves can be ducted inside the magnetic dip in Jupiter's magnetosphere [ABSTRACT FROM AUTHOR]

In this paper, the oblique propagation of the ion-acoustic quantum soliton in polarized quantum plasma including relativistic degenerate electrons and positrons is studied. By using the reductive perturbation method, we derived the ZK equation for this model. This equation shows that in presence of the negative ion there are two slow and fast ion-acoustic modes. Our numerical results indicate that there are only compressive and refractive solitons for fast and slow modes, respectively. The effect of the negative ion parameters on the amplitude and width of the ion-acoustic quantum soliton are studied, as well. [ABSTRACT FROM AUTHOR]

The past measurements of the plasma density and potential profiles near the exit of the keeper electrode in a hollow cathode device suggested that turbulent ion acoustic fluctuations and ionization instability in the cathode plume significantly increased the energy of the ions that flow from this region. The lifetime of keeper electrode is limited by sputtering or ion bombardment of the Molybdenum surface exposed to the discharge plasma. Increases in the cathode gas flow reduce the amplitude of the fluctuations and the number and energy of the energetic ions, which decreases the erosion rate of the keeper electrodes. However, as the cathode gas flow is raised for a given discharge current, the performance of a 5-kW Annular-Geometry Ion Engine (AGI-Engine) declines. There is a strong relationship between the performance and the lifetime of the ion thruster. To validate whether the 20-A hollow cathode satisfied China’s communication satellite platform’s application requirement for North-South station keeping, this paper analyzed the effect of the cathode gas flow on the performance and the lifetime of the AGI-Engine. Different from the previous methods, this paper first tracked the movement of energetic ions generated in the plume of the hollow cathode, predicted erosion rates, found where they hit the keeper electrode, and then determined the amount of material that they sputtered. A review of past experimental results was presented first. Next, based on the existing experimental data, theoretical analysis and numerical calculations were performed to determine the optimum gas flow range and the performance curve of the 20-A hollow cathode. The results showed that the primary erosion mechanism of the keeper electrode was caused by impact from Charge Exchange Xenon (CEX) ions, which caused the cathode orifice to be widened and attenuated over time. However, heavy double xenon ($\text{X}_{\text{e}}^{++}$) ions, which struck the keeper electrode more severely than CEX ions, were the most crucial factor that limited the lifetime of the 20-A hollow cathode due to their high energy and large mass. [ABSTRACT FROM AUTHOR]

In this paper, we propose a relativistic quantum many-body theory for the collective modes in spinor quantum electrodynamic plasma. Different from the usual quantization scheme, we use the self-consistency nontrivial background field method in the framework of thermo field dynamics, in which the resulting quanta are temperature-dependent particles instead of the observable ones such as electrons, positrons, and photons. The theory provides a general scheme for many-body physics, which overcomes the disadvantages of random phase, Hartree–Fock, or other equivalent mean-field approximations. The essential point for our theory is to exactly evaluate the background fields. In this paper, we propose a general and efficient method to determine them, which we name as the “classical limit method” for convenience. To demonstrate how to apply the theory, we discuss the collective modes in unmagnetized electron–positron plasma, in both the low-energy and high-energy limits. It yields the well-known dispersion relations of longitudinal and transverse modes for non-relativistic degenerate plasmas, at zero and nonzero temperature. Furthermore, it gives the additional relativistic and vacuum fluctuation corrections, including increasing mass, decreasing effective charge, finite light velocity influence on the dispersion relation, and virtual charge redistribution. The last effect is reported for the first time. [ABSTRACT FROM AUTHOR]

The Cairns-distributed electrons and positive ions in a plasma made up of a negative dust fluid are taken into account to examine the presence of arbitrary amplitude dust-acoustic solitons. It has previously been noted that nonthermal ions and thermal electrons generate both compressive and rarefactive solitons. In this paper, we noticed that nonthermal electrons together with nonthermal ions are responsible for producing the rarefactive solitons. It is found that the Sagdeev potential strongly depends on plasma parameters, such as nonthermal index α and Mach number, which, in turn, influence the Sagdeev potential and solitons significantly. We also found that the critical match number and height of soliton increase with the nonthermal parameter α. We further note that the Sagdeev potential as a function of potential φ becomes more negative and the amplitude of the soliton also enhances as the value of Mach number rises. It is concluded that the model presented here based on nonthermal ions and electrons in a negative dust fluid provides a worthy interpretation for electrostatic solitons observed in space plasmas. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the behavior of dust ion acoustic solitary waves (DIASWs) with arbitrary amplitudes in a magnetized anisotropic dusty plasma that includes inertial hot ion fluid, electrons following a Kappa distribution, and negatively charged dust particles in the background. An ambient magnetic field aligns with the x-direction, while the wave propagation occurs obliquely to the ambient magnetic field. In the linear regime, two distinct modes, namely fast and slow modes, are observed. We employ the Sagdeev pseudo-potential method to analyze the fundamental properties of arbitrary amplitude DIASWs. Additionally, we examine how various physical parameters influence the existence and characteristics of symmetric planar dust ion acoustic solitary structures (DIASs). The characteristics of the solitary structures are greatly influenced by the dust concentration, the electrons superthermality (spectral) index, the obliquity parameter, the magnetic field, the parallel ion pressure and the perpendicular ion pressure. The results show that the amplitude and width of both compressive and rarefactive DIASWs are sensitive to the degree of electron superthermality and dust concentration. Additionally, it is shown that the propagation features of DIASWs are highly affected by the parallel component of ion pressure as compared to perpendicular component of ion pressure. [ABSTRACT FROM AUTHOR]

In this paper, traveling wave solutions of some nonlinear stochastic evolution equations emerging in miscellaneous fields such as modeling of flame propagation, magneto-acoustic waves in plasma and small-amplitude water waves with surface tension are investigated. By means of Galilean transformation and tanh method, we obtain some exact solutions such as kink wave solution, solitary wave solution and periodic solution. To illustrate the impact of noise on the solutions, we assigned different noise functions for the external noise. The results showed that the waveform deforms as the noise intensity increases. [ABSTRACT FROM AUTHOR]

Using an automated novel approach we conduct a reproducible systematic survey of electromagnetic ion cyclotron wave activity detected by Van Allen Probe B during the time period 2013 January 1–2019 July 15. We identify approximately 500 hr of EMIC wave activity, an occurrence rate of ∼ 0.85%. Accounting for satellite dwell time, we find that EMIC waves preferentially occur on the dayside, between 9 and 15 magnetic local time. This is true for both the H+ and He+wavebands. Higher amplitude waves are found at higher values of L shell, while weaker waves occur at low L. The highest amplitudes are concentrated at high L near dawn and dusk. It is also found that EMIC wave occurrence is enhanced during periods of strong geomagnetic activity, with an occurrence rate of 2.7%. During storm times, waves preferentially occur in the afternoon and early evening sectors. The full list of electromagnetic ion cyclotron wave detection times and their properties is made publicly available to the community. This provides a reference catalog for comparison with other magnetospheric phenomena and other wave databases. Plain Language Summary: Electromagnetic Ion Cyclotron (EMIC) waves are found throughout Earth's magnetosphere and the solar system. These waves in Earth's magnetosphere interact with the ring current and radiation belt population and push these particles into our atmosphere. Thus, it is useful to know when and where these waves occur. In this paper, we present a new approach toward identifying these waves in large data sets. Using this new approach, we identified 500 hr of EMIC waves from the Van Allen Probe B data set between Jan 2013–July 2019. Our catalog of events follows similar statistics found for EMIC waves by others, validating our methodology. Like others, we found that the waves occur more frequently on the dayside of the Earth. Higher amplitude waves were found at greater distances from the Earth, close to the edge of the magnetosphere. It was also found that the wave activity was greater during periods of geomagnetic activity than during quiet conditions. And in the interest of open science, we have made both the detection code and the list of waves available to the public. Key Points: We conduct a survey of electromagnetic ion cyclotron waves detected by Van Allen Probe B between 2013 January 1–2019 July 15The overall EMIC wave occurrence rate was ∼0.85% with a dayside preference. Stronger waves are found at higher L shells and during stormsThe full list of EMIC wave detection times and their properties is made publicly available to the community, along with the methodology [ABSTRACT FROM AUTHOR]

In this paper, propagation characteristics of obliquely propagating nonlinear magnetosonic waves in hot nonthermal plasmas have been studied. The expressions of modified temperatures have been derived for non-Maxwellian Q-nonextensive and (r, q) distributions and then incorporated into the one-fluid magnetohydrodynamic model. By employing the reductive perturbation technique, we derived the linear dispersion relation (LDR) and nonlinear Kadomstev–Petvashvilli (KP) equation for slow and fast magnetosonic wave modes in two dimensions. We then investigated the LDR and nonlinear propagation of KP solitons for both the slow and fast mode magnetosonic waves and found that propagation characteristics are significantly altered by considering the effect of modified temperature. The results presented here would depict a realistic picture of the propagation of nonlinear magnetosonic waves in non-Maxwellian plasmas. [ABSTRACT FROM AUTHOR]

Preserving the quality of a positron beam in a plasma-based accelerator, where a wakefield suitable for positron transport and acceleration is generated by means of an electron filament, is challenging. This is due to the nature of the wakefields, characterized by focusing fields that vary nonlinearly in the transverse direction, and by accelerating fields that are non-uniform. These fields also change slice-by-slice along the beam. Maintaining a high beam quality is pivotal for application of positron beams in a plasma-based collider. In this paper, we show that an initial background plasma temperature can help mitigate the positron beam quality degradation in plasma-based accelerators that rely on electron filaments. We show that temperature effects broaden the electron filament and smooth radially both the non-linear transverse and the non-uniform longitudinal wakefields. Using warm plasmas opens up new possibilities to improve beam quality in several plasma-based positron acceleration concepts. [ABSTRACT FROM AUTHOR]

In this paper, expressions of number densities for electron trapping for generalized (r, q), kappa, and Cairns distribution functions, respectively, are reported using the approach adopted by Landau and Lifshitz for Maxwellian trapping of electrons. For illustrative purposes, dispersive and dissipative equations for ion-acoustic waves are obtained in the presence of non-Maxwellian trapped electrons in the small amplitude limit. The solutions of the modified dispersive and dissipative nonlinear equations are reported, and a graphical analysis is given to present a detailed comparison of non-Maxwellian and Maxwellian trapping. The results presented here, to the best of authors' knowledge, are a first attempt of this kind. It is expected that the present investigation will unravel new horizons for future research and encourage the researchers to search for the nonlinear structures presented in this paper in the satellite data. [ABSTRACT FROM AUTHOR]

Recent observations have reported that magnetosonic waves can exhibit rising‐tone structures in the frequency‐time spectrogram. However, the generation mechanism has not been identified yet. In this paper, we investigate the generation of rising‐tone magnetosonic waves in the terrestrial magnetosphere using 1‐D particle‐in‐cell (PIC) simulations, in which the plasma consists of three components: cool electrons, cool protons and ring distribution protons. We find that the magnetosonic waves excited by the ring distribution protons can form a rising‐tone structure with frequency of the structure ranging from about 0.5Ωlh to nearly Ωlh, where Ωlh is the lower hybrid frequency. It is further demonstrated that the rising frequency of magnetosonic waves can be accounted for by the scattering of ring distribution protons. Moreover, the rising‐tone timescale obtained by PIC simulation is compared with the satellite observation. Our findings provide some new insights to understand the nonlinear evolution of plasma waves in the Earth's magnetosphere. Plain Language Summary: Magnetosonic waves in the Earth's inner magnetosphere often exhibit a series of harmonics of the local proton gyrofrequency. Recent observations found that they also have some other features, such as rising‐tone spectra and quasiperiodicity in time. Since these phenomena are similar to the rising‐tone chorus and electromagnetic ion cyclotron waves, many researchers speculated the generation of rising‐tone magnetosonic waves may be also related to the nonlinear wave‐particle interaction. In spite of the speculation, the specific generation mechanism of rising‐tone magnetosonic waves has not been identified yet. In this paper, we perform 1‐D particle‐in‐cell (PIC) simulations to investigate the generation of rising‐tone magnetosonic waves. It is found that the magnetosonic waves excited by the ring distribution protons can form a rising‐tone structure. In addition, we also demonstrate that the rising‐tone magnetosonic waves can be accounted for by the scattering of ring distribution protons. Key Points: Using 1‐D PIC simulations, we have investigated the generation of rising‐tone magnetosonic waves excited by ring distribution protonsThe rising‐tone structure of magnetosonic waves can be accounted for by the scattering of ring distribution protonsPIC simulations show that the rising‐tone timescale depends on the initial ring proton density and thermal speed [ABSTRACT FROM AUTHOR]

Different kinds of waves and instabilities in the F-region of the ionosphere excited by the relative streaming of the dust beam to the background plasma are studied in the present paper. The dispersion relations of different waves are obtained on different time scales. It is found from our numerical results that there are both a stable upper hybrid wave on the electron vibration time scale and a stable dust ion cyclotron wave on the ion vibration time scale. However, the chaotic behaviour appears on the dust particles vibration time scale due to the relative streaming of the dust particles to the background plasma. Such instabilities may drive plasma irregularities that could affect radar backscatter from the clouds. [ABSTRACT FROM AUTHOR]

In light of fractional theory, this paper presents several new effective solitonic formulations for the Langmuir and ion sound wave equations. Prior to this study, no previous research has presented the comparision and obtained the generalized fractional soliton solutions of this kind with power law kernel and Mittag-Leffler kernel. The ion sound and Langmuir wave equations are essential in plasma physics, offering insights into the collective behavior of charged particles in plasmas and enabling diagnostics and control of these complex, ionized gas systems. The two distinct fractional order differential operators are substituted for the traditional order derivative to reshape the examined model. The Atangana-Baleanu non-singular and non-local operator and conformable fractional operator are the fractional-order operators that are used to create the fractional complex system equations for Langmuir waves and ion sound. A constructive approach new auxiliary equation method utilizes to obtain the exact analytical soliton solutions for ion sound and Langmuir wave equation. A wide range of soliton solutions is obtained, including mixed complex solitary shock solutions, singular solutions, mixed shock singular solutions, mixed trigonometric solutions, mixed singular solutions, exact solutions, mixed periodic solutions, and mixed hyperbolic solutions, dark soliton, bright soliton, trigonometric solutions, periodic results, and hyperbolic results. The solitons solution of the ion sound and Langmuir wave equations lies in their ability to maintain wave stability, their role in modeling wave propagation and nonlinear effects, their potential use as diagnostic tools, and their relevance in wave-particle interactions in plasma physics. The solitons provide a valuable framework for understanding the behavior of waves in plasmas and offer insights into the complex dynamics of these charged particle systems. A graphical comparison analysis of a few solutions is also shown here, taking into account appropriate parametric values through the use of the software package. Moreover, the results of this study have important implications for Hamilton's equations and generalized momentum, where solitons are employed in long-range interactions. [ABSTRACT FROM AUTHOR]

In this paper, two‐dimensional hybrid simulations are used to study wave excitation and evolution throughout a low‐Mach number quasi‐parallel shock. Simulation results show that quasi‐parallel fast magnetosonic waves, ion Bernstein waves with harmonics and possible Alfven/ion cyclotron waves can be excited in the upstream region, and their small phase velocities compared to injected flow velocity results in the convection to the shock front where they are mode converted into several groups of downstream waves, including Alfven waves along the directions parallel to downstream average magnetic fields and perpendicular to the shock normal, the quasi‐perpendicular kinetic slow waves and possible kinetic Alfven waves. We suggest that downstream Alfven waves originate from the mode conversion of upstream quasi‐parallel fast magnetosonic waves with left‐hand polarization in the downstream rest frame under helicity conservation, while the downstream left‐hand polarized kinetic slow waves and right‐hand polarized kinetic Alfven waves can be from the upstream quasi‐perpendicular ion Bernstein waves. Key Points: Upstream and downstream waves at a low‐Mach number quasi‐parallel shock are investigated by 2‐D hybrid simulationsUpstream quasi‐parallel and quasi‐perpendicular waves are excited by the interaction of injected flow and backstreaming ionsDownstream waves are generated by the mode conversion of upstream waves [ABSTRACT FROM AUTHOR]

The solar wind ion transport across the magnetopause is one of the main sources of plasma for the Earth's magnetotail. Such a transport is supported by various dynamic processes at the flank magnetopause, where wave‐particle interactions play a crucial role in ion flow thermalization and diffusion across magnetic field surfaces of the magnetopause tangential discontinuity. In this paper we numerically model such ion thermalization by the most intense electromagnetic waves observed in the magnetosheath, kinetic Alfven waves. We aim to develop an approach for long‐term simulations of ion scattering by waves and ion dynamics around realistic magnetopause magnetic fields. This approach is based on a combination of test particle simulations and stochastic differential equations modeling ion diffusion in velocity space. We demonstrate that for realistic magnetopause configuration and wave characteristics, the magnetosheath ion flow can be substantially thermalized around the magnetopause. This result explains observations of ion energy conservation across the flank magnetopause: kinetic and thermal energies of flowing magnetosheath ions approximately equal to the thermal energy of stagnant magnetospheric ions. Key Points: We model the ion flow thermalization by kinetic Alfven waves around the flank magnetopauseThe model uses stochastic differential equations for particle trajectories to include effects of wave‐particle interactionsScattering and thermalization may explain ion energy conservation across the magnetopause [ABSTRACT FROM AUTHOR]

Since Snyder was the first to present the theory of quantized space–time, many studies have been devoted to various phenomenological aspects of this theory. In this paper, we investigate the plasma frequency in a generalized Snyder space. The electron and ion plasma waves in a generalized Snyder space are found. We estimate the upper bound on the isotropic minimal length scale, which is close to m. [ABSTRACT FROM AUTHOR]

Electrostatic waves with frequencies that are integer multiples of the electron plasma frequency have been observed since the early days of laboratory experiments on beam–plasma interactions, and also in experiments made in the space environment. These waves have also appeared in numerical experiments, and can be explained in the context of weak turbulence theory. This paper presents results obtained by numerical solution of the equations of weak turbulence theory, which show the coupled time evolution of the amplitudes of harmonic waves and of the amplitudes of Langmuir and ion acoustic waves, and the time evolution of the electron distribution function. The results are obtained considering a two-dimensional geometry, considering harmonics up to n = 5, and are consistent with earlier results obtained by one-dimensional analyses. [ABSTRACT FROM AUTHOR]

A theoretical investigation of ion-acoustic solitons in an unmagnetized plasma consisting of cold ions and regularized κ-distributed electrons has been carried out. The properties of stationary solitary structures are briefly studied by the reductive perturbation method in the small amplitude limit. It is found that in the small κ region, the ion-acoustic solitary waves propagate more slowly in the case of regularized κ distribution than in the case of standard κ distribution. The regularized κ-distributed electrons affect the width and amplitude of the solitary waves. As the cutoff parameter α increases, the amplitudes of both the compressive and rarefactive solitary waves decrease, and their widths also decrease. In addition, for a given value of κ, positive potential solitons will appear at large α, while negative potential solitons will appear at small α. The results of this paper may be useful for understanding nonlinear electrostatic phenomena in space plasmas. [ABSTRACT FROM AUTHOR]

The KPI equation is one of most well-known nonlinear evolution equations, which was first used to described two-dimensional shallow water wavs. Recently, it has found important applications in fluid mechanics, plasma ion acoustic waves, nonlinear optics, and other fields. In the process of studying these topics, it is very important to obtain the exact solutions of the KPI equation. In this paper, a general Riccati equation is treated as an auxiliary equation, which is solved to obtain many new types of solutions through several different function transformations. We solve the KPI equation using this general Riccati equation, and construct ten sets of the infinite series exact solitary wave solution of the KPI equation. The results show that this method is simple and effective for the construction of infinite series solutions of nonlinear evolution models. [ABSTRACT FROM AUTHOR]

Recent studies have found that magnetic dips resulting from the diamagnetic motion of injected plasmas can provide a favorable environment for electromagnetic ion cyclotron (EMIC) wave excitation. However, another critical question how magnetic dips affect the propagation of EMIC waves remains uncovered. In this paper, with plasma environment as well as wave properties observed in a typical event, theoretical analysis about this topic has been provided. Our results show that in this event both H+ band and He+ band EMIC waves can be constrained in the magnetic dip, which is consistent with the wave emissions observed inside the magnetic dip. The energetic protons have also been found to fall around the saturated states, suggesting a stable balance built among EMIC waves, energetic protons, and magnetic structures. Our results provide one new insight into the EMIC wave propagation inside a magnetic dip and their important roles in the dynamics of magnetic dips. Plain Language Summary: Magnetic structures and electromagnetic waves are two of the most common phenomena in space plasmas. One key scientific topic is to study the relation between them. Recent studies have found that plasma waves can be excited inside magnetic structures. Specifically, electromagnetic ion cyclotron (EMIC) waves have been reported to be excited in a large‐scale magnetic dip resulting from the diamagnetic drift of energetic protons. Here, we focus on the effect of the magnetic dip on the propagation of EMIC waves. If EMIC waves can be ducted inside the magnetic dip, they will be involved into the total balance of the magnetic structure since these waves would influence the dynamics of energetic protons through long‐time scattering effects. Thus, our result will be of importance to understanding the dynamics of magnetic dips. Key Points: Theoretical analysis about the effects of magnetic dips on electromagnetic ion cyclotron (EMIC) wave propagations has been givenOur theoretical result shows that both H+ and He+ band EMIC waves can be ducted inside the magnetic dipEnergetic protons inside the magnetic dip are verified near the saturated states, suggesting a stable force balance in the magnetic dip [ABSTRACT FROM AUTHOR]

By constructing an empirical model of the spectral and latitudinal distribution of ion cyclotron waves on the basis of Cassini datasets, we investigate the resonant interactions between ion cyclotron waves and radiation belt electrons at Saturn. Calculations based on quasi‐linear bounce‐averaged diffusion coefficients show that at Saturn ion cyclotron waves can efficiently pitch angle scatter >∼1 MeV to tens of MeV electrons into the loss cone thereby inducing precipitation loss, while the mixed and momentum scattering effects are typically negligible. The resultant electron loss timescales range from a few to tens of minutes, which in fact decrease significantly with increasing L‐shell at L = 4–6. We also find that the kinetic effects introduced by pick‐up ring particles cause distinct changes in pitch angle scattering efficiency for lower energy electrons (<3 MeV at L = 5). Our results demonstrate that ion cyclotron waves play a significant role in the dynamics of Saturn's radiation belt electrons. Plain Language Summary: Ion cyclotron waves are a common electromagnetic wave mode in the planetary magnetospheres. At Saturn, ion cyclotron waves are usually observed with wave frequencies near the gyro‐frequency of water‐group ions (e.g., O+, OH+, and H2O+). They are known to be excited by a ring distribution of the pick‐up water‐group ions which are extracted from the extended neutral clouds. In this paper, we investigate the resonant interactions between ion cyclotron waves and radiation belt electrons at Saturn. By constructing an empirical model of the spectral and latitudinal distribution of ion cyclotron waves based on Cassini observations, we calculate the bounce‐averaged electron diffusion coefficients and resultant electron loss timescales. Our results suggest that Saturn's ion cyclotron waves can cause efficient precipitation loss of radiation belt electrons by scattering them into the loss cone. The corresponding loss timescales range from a few to tens of minutes, decreasing with increasing radial distance from Saturn. Our results confirm the important role of ion cyclotron waves in the dynamics of Saturnian radiation belt electrons. Key Points: The resonant interactions between ion cyclotron waves and radiation belt electrons at Saturn are investigatedIon cyclotron waves can efficiently pitch angle scatter >∼1 MeV to tens of MeV electrons into the loss cone for precipitation lossThe resultant electron loss timescales range from a few to tens of minutes, which decrease significantly with increasing L‐shell over L = 4–6 [ABSTRACT FROM AUTHOR]

In this paper, we discuss the time-fractional mKdV-ZK equation, which is a kind of physical model, developed for plasma of hot and cool electrons and some fluid ions. Based on the properties of certain employed truncated M-fractional derivatives, we reduce the time-fractional mKdV-ZK equation to an integer-order ordinary differential equation utilizing an adequate traveling wave transformation. Further, we derive a dynamical system to present bifurcation of the equation equilibria and show existence of solitary and kink singular wave solutions for the time-fractional mKdV-ZK equation. Furthermore, we establish symmetric solitary, kink, and singular wave solutions for the governing model by using the ansatz method. Moreover, we depict desired results at different physical parameter values to provide physical interpolations for the aforementioned equation. Finally, we introduce applications of the governing model in detail. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In Paper I, we successfully used an external circuit to significantly damp the Breathing Mode (BM) oscillations in 2D particle-in-cell self-consistent simulations of the axial–azimuthal plane of a Hall thruster. We also introduced the two-point power spectral density reconstruction method (PSD2P) used to analyze electrostatic instabilities and generate dispersion diagrams in azimuthal and axial directions, at various times during the BM period. Here, a 3D Dispersion Relation (DR) for electrostatic modes is calculated by linearizing the continuity/momentum fluid equations for electrons and ions. We show that by taking the appropriate limits, this relation can be simplified to derive the DRs of some well-known E × B instabilities, such as the electron cyclotron drift instability and its evolution to the Ion Acoustic Wave (IAW), and the Ion Transit-Time Instability (ITTI). The PSD2P diagrams demonstrate the importance of considering the 2D nature of the IAW and ITTI, which have been previously considered to be mono-dimensional (azimuthal and axial, respectively). In particular, we show that the IAW grows near the maximum of the magnetic field and due to its axial components propagates toward both the anode and the cathode (in addition to the well-known azimuthal propagation). The resulting wavefront is, therefore, bent. By analogy to the propagation of acoustic waves in gases, it is proposed that the cause of the IAW wavefront bending is the strong electron temperature gradients in the axial direction. We also show that the ITTI has a strong positive growth rate when a small azimuthal component is present. Finally, we observe that the ITTI significantly affects the discharge current. [ABSTRACT FROM AUTHOR]

In this series of papers, we present statistical maps of mirror-mode-like (MM) structures in the magnetosheaths of Mars and Venus and calculate the probability of detecting them in spacecraft data. We aim to study and compare them with the same tools and a similar payload at both planets. We consider their dependence on extreme ultraviolet (EUV) solar flux levels (high and low) and, specific to Mars, on Mars Year (MY) as well as atmospheric seasons (four solar longitudes Ls). We first use magnetic-field-only criteria to detect these structures and present ways to mitigate ambiguities in their nature. In line with many previous studies at Earth, this technique has the advantage of using one instrument (a magnetometer) with good time resolution, facilitating comparisons between planetary and cometary environments. Applied to the magnetometer data of the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft from November 2014 to February 2021 (MY32–MY35), we detect events closely resembling MMs lasting in total more than 170000 s, corresponding to about 0.1 % of MAVEN's total time spent in the Martian plasma environment. We calculate MM-like occurrences normalised to the spacecraft's residence time during the course of the mission. Detection probabilities are about 1 % at most for any given controlling parameter. In general, MM-like structures appear in two main regions: one behind the shock and the other close to the induced magnetospheric boundary, as expected from theory. Detection probabilities are higher on average in low-solar-EUV conditions, whereas high-solar-EUV conditions see an increase in detections within the magnetospheric tail. We tentatively link the former tendency to two combining effects: the favouring of ion cyclotron waves the closer to perihelion due to plasma beta effects and, possibly, the non-gyrotropy of pickup ion distributions. This study is the first of two on the magnetosheaths of Mars and Venus. [ABSTRACT FROM AUTHOR]

In a two-ion-species plasma with disparate ion masses, heavy ions tend to concentrate in the low-temperature region of collisionally magnetized plasma and in the high-temperature region of collisionally unmagnetized plasma, respectively. Moreover, collisional magnetization can be determined as the ratio of the light ion gyrofrequency to the collision frequency of light and heavy ion species, and the behavior of this effect in the intermediate regime of partially magnetized plasma is predominantly dependent on this Hall parameter. Multi-ion cross-field transport has been described before in the collisionally magnetized plasma regime, and generalized pinch relations, which describe densities of ion species in equilibrium in that plasma, are found in the literature. In this paper, the role of collisional magnetization and Larmor magnetization in multi-ion collisional transport is clarified, and generalized pinch relations are extended to the partially magnetized regime in which the ion Hall parameter may be small, as long as electrons remain collisionally magnetized. Equilibrium ion density profiles have the same dependence on external forces and on each other regardless of collisional magnetization of ions. The expansion of the range of validity of multi-ion collisional transport models makes them applicable to a wider range of laboratory plasma conditions. In particular, ion density profiles evolve sufficiently fast for radial impurity transport to be observable around stagnation on MagLIF, leading to expulsion of heavy ion impurities from the hotspot as long as plasma becomes sufficiently collisionally magnetized during the implosion. [ABSTRACT FROM AUTHOR]

In the present paper, we consider the nonlinear interaction of high frequency intense electromagnetic beam with degenerate electron plasmas. In a slowly varying envelop approximation, the beam dynamics is described by the couple of nonlinear equations for the vector and scalar potentials. Numerical simulations demonstrate that for an arbitrary level of degeneracy the plasma supports existence of axially symmetric 2D solitons which are stable against small perturbations. The solitons exist if the power trapped in the structures, being the growing function of soliton amplitude, is above a certain critical value but below the value determining by electron cavitation. The robustness of obtained soliton solutions was verified by simulating the dynamics of initial Gaussian beams with parameters close to the solitonic ones. After a few diffraction lengths, the beam attains the profile close to the profile of the ground state soliton and propagates for a long distance without detectable distortion. The simulations have been performed for the input Gaussian beams with parameters far from ground state solutions. It is shown that the beam parameters are oscillating near the parameters of the ground soliton solution and thus the formation of oscillating waveguide structures takes place. [ABSTRACT FROM AUTHOR]

Nonlinear kinetic structures, called electron phase-space holes (EHs), are regularly observed in space and experimental magnetized plasmas. The existence of EHs is conditioned and varies according to the ambient magnetic field and the parameters of the electron beam(s) that may generate them. The objective of this paper is to extend the 3D Bernstein–Greene–Kruskal model with cylindrical geometry developed by L.-J. Chen et al. ["Bernstein–Greene–Kruskal solitary waves in three-dimensional magnetized plasma," Phys. Rev. E 69, 055401 (2004)] and L.-J. Chen et al., ["On the width-amplitude inequality of electron phase space holes," J. Geophys. Res. 110, A09211 (2005)] to include simultaneously finite effects due to (i) the strength of the ambient magnetic field B 0 , by modifying the Poisson equation with a term derived from the electron polarization current, and (ii) the drift velocity ue of the background plasma electrons with respect to the EH, by considering velocity-shifted Maxwellian distributions for the boundary conditions. This allows us to more realistically determine the distributions of trapped and passing particles forming the EHs, as well as the width-amplitude relationships for their existence. [ABSTRACT FROM AUTHOR]

We present a statistical analysis of electrostatic solitary waves observed aboard Magnetospheric Multiscale spacecraft in the Earth's magnetosheath. Applying single‐spacecraft interferometry to several hundred solitary waves collected in about 2‐minute interval, we show that almost all of them have the electrostatic potential of positive polarity and propagate quasi‐parallel to the local magnetic field with plasma frame velocities of the order of 100 km/s. The solitary waves have typical parallel half‐widths from 10 to 100 m that is between 1 and 10 Debye lengths and typical amplitudes of the electrostatic potential from 10 to 200 mV that is between 0.01% and 1% of local electron temperature. The solitary waves are associated with quasi‐Maxwellian ion velocity distribution functions, and their plasma frame velocities are comparable with ion thermal speed and well below electron thermal speed. We argue that the solitary waves of positive polarity are slow electron holes and estimate the time scale of their acceleration, which occurs due to interaction with ions, to be of the order of one second. The observation of slow electron holes indicates that their lifetime was shorter than the acceleration time scale. We argue that multi‐spacecraft interferometry applied previously to these solitary waves is not applicable because of their too‐short spatial scales. The source of the slow electron holes and the role in electron‐ion energy exchange remain to be established. Plain Language Summary: Earth's magnetosheath is a highly turbulent medium and an ideal natural laboratory for the analysis of plasma turbulence. Spacecraft measurements showed that high‐frequency electric field fluctuations in the Earth's magnetosheath are predominantly electrostatic and consist, particularly, of electrostatic solitary waves with bipolar parallel electric fields. The properties of these electrostatic fluctuations have been largely unaddressed and, moreover, the results of previous studies were inconsistent. In this paper, we present a statistical analysis of electrostatic solitary waves observed aboard Magnetospheric Multiscale in the Earth's magnetosheath. We revealed that most of the solitary waves are Debye‐scale structures with the electrostatic potential of positive polarity and typical amplitudes between 0.01% and 1% of local electron temperature. We demonstrated that the solitary waves must be electron holes, purely kinetic structures produced in a nonlinear stage of various electron‐streaming instabilities. Even more critical is that these structures are slow; their plasma frame velocities are well below electron thermal speed but coincide with the velocities of the bulk of ions. While the source of electrostatic fluctuations in Earth's magnetosheath could not be revealed, the finding that these fluctuations can be slow implies they can facilitate efficient energy exchange between ions and electrons. Key Points: Statistical analysis of 645 solitary waves in the Earth's magnetosheath revealed that 630 of them are electron holesThe electron holes are associated with quasi‐Maxwellian ion velocity distribution functionsThe electron hole velocities are comparable with those of the bulk of ions and well below electron thermal speed [ABSTRACT FROM AUTHOR]

Electromagnetic ion cyclotron (EMIC) waves lead to rapid scattering of relativistic electrons in Earth's radiation belts, due to their large amplitudes relative to other waves that interact with electrons of this energy range. A central feature of electron precipitation driven by EMIC waves is deeply elusive. That is, moderate precipitating fluxes at energies below the minimum resonance energy of EMIC waves occur concurrently with strong precipitating fluxes at resonance energies in low‐altitude spacecraft observations. This paper expands on a previously reported solution to this problem: nonresonant scattering due to wave packets. The quasi‐linear diffusion model is generalized to incorporate nonresonant scattering by a generic wave shape. The diffusion rate decays exponentially away from the resonance, where shorter packets lower decay rates and thus widen the energy range of significant scattering. Using realistic EMIC wave packets from δf particle‐in‐cell simulations, test particle simulations are performed to demonstrate that intense, short packets extend the energy of significant scattering well below the minimum resonance energy, consistent with our theoretical prediction. Finally, the calculated precipitating‐to‐trapped flux ratio of relativistic electrons is compared to ELFIN observations, and the wave power spectra is inferred based on the measured flux ratio. We demonstrate that even with a narrow wave spectrum, short EMIC wave packets can provide moderately intense precipitating fluxes well below the minimum resonance energy. Plain Language Summary: Electromagnetic ion cyclotron (EMIC) waves are one of the most important plasma emissions in the near‐Earth space. When electrons experience an approximately constant EMIC wave phase in gyration, they resonate with these waves and are scattered to precipitate to the Earth's upper atmosphere. Such cyclotron resonance between electrons and EMIC waves are typically above 1 MeV of electron energy. However, spacecraft at low Earth orbit often observe that electrons in the hundreds of keV range, which are not in resonance with EMIC waves, precipitate simultaneous with those >1 MeV. Strongly modulated EMIC wave packets are promising in precipitating the sub‐MeV electrons through nonresonant interactions. Here, the theoretical model of nonresonant scattering is verified for realistic EMIC wave packets from self‐consistent computer simulations. EMIC wave power spectra are inferred from electron precipitation measurements by ELFIN. Short EMIC wave packets are shown to give a better agreement between the theoretical and observed precipitating‐to‐trapped flux ratios. Key Points: The theoretical model of nonresonant scattering is verified for wave packets derived from self‐consistent simulationsShort EMIC wave packets extend the energies of efficient scattering well below the minimum resonance energy, consistent with the theoryEMIC wave power spectra are inferred from ELFIN observations of relativistic electron precipitation, including nonresonant scattering [ABSTRACT FROM AUTHOR]

In this paper, we study obliquely propagating of small amplitude ion acoustic waves (IAWs) in non-relativistic cold plasma in which the ions are viscous fluid, electrons distribution is Maxwellian and external magnetic field varies in space. Using the reductive perturbation method, a nonlinear equation which complies with Korteweg–de Vries–Burgers (KdVB) equation is derived for this model. It is shown that a new effective dissipative which depends on the ion kinematic viscosity and varying in the magnetic field is appeared in the plasma. We show that the complete set of equations, by considering the varying magnetic field and viscosity effect, create IA waves which radiate energy as oscillatory shock wave during their travelling in the medium. [ABSTRACT FROM AUTHOR]

This paper comprehensively investigates the oblique propagation of ion-acoustic solitary waves (IASWs) with arbitrary amplitude in a magnetoplasma consisting of inertialess non-Maxwellian (nonthermal) electrons, inertialess Maxwellian positrons, and inertial adiabatically heated ions. It is postulated that the positive ions demonstrate adiabatic behavior that is distinguished by anisotropic thermal pressure. The study utilizes Sagdeev's pseudopotential theory to analyze the fluid equations of the plasma model and reduce them to the energy equation. Different plasma configuration factors, such as nonthermal parameters, positron concentration, and parallel and perpendicular ion pressure, are being studied to see how they affect the properties of solitary waves with large amplitudes. The findings demonstrate the simultaneous coexistence of compressive and rarefactive IASWs, significantly influenced by positrons and nonthermal electron parameters. The study provides valuable insights into wave phenomena in magnetized plasmas and presents possible applications in both Space and laboratory plasma environments. [ABSTRACT FROM AUTHOR]

In this paper, we consider the dynamics of anisotropic Langmuir turbulence in the case of induced scattering of Langmuir waves by thermal ions of solar plasma in a homogeneous approximation. The temporal change in the spectral energy density of plasma waves is calculated as a function of the wavenumber and direction of the wave vector. It is shown that upon induced scattering of plasma waves by plasma ions, not only is energy transferred from waves with large values of the wavenumber k to waves with smaller k values, but the angular distribution of plasma waves, which remains anisotropic, also changes. [ABSTRACT FROM AUTHOR]

Plasma waves are considered to be a unique feature of space plasmas which have a universal presence. Plasma waves are observed in almost all solar system objects such as the Sun, planets, planetary satellites, interplanetary medium, etc. Plasma waves are predicted to exist in the interstellar medium, etc. Plasma waves can exist around the comets also. The interaction of solar radiation with the neutral cometary surroundings results in the formation of a plasma environment around a comet which is capable of sustaining plasma waves. Plasma waves are observed around comets Giacobini–Zinner, Halley, Grigg–Skjellerup, Borrelly, and Churyumov–Gerasimenko. Some other comets such as Humason, Brorsen–Metcalf, Wirtanen, etc. also have a plasma environment but the existence of plasma waves there is yet to be investigated. In this review paper, the plasma waves observed around five main comets are discussed [ABSTRACT FROM AUTHOR]

Electrostatic solitary waves (ESW) and solitons are widely observed nonlinear plasma phenomena in various space environments, which may be generated by the electron streaming instability as shown in many particle simulations. The predicted electron holes associated with the ESW, however, are not observed by the recent high resolution spacecraft. This raises a possibility for the ion acoustic solitons being the potential candidate, which are described by the Sagdeev potential theory with hot electrons and cold ions being treated by the kinetic equilibrium and fluid models, respectively. The assumption of T i / T e = 0 adopted in the theoretical models for ion acoustic solitons, however, imposes a great constraint for the space applications considering that T i / T e may vary in a wide range of 0.1–10 in the Earth's space environments. This paper examines the effect of T i / T e on ion acoustic solitons by including a finite temperature in the fluid equations for the ions, which, however, can no longer be solved based on the standard Sagdeev potential method. It is shown based on the nonlinear theory that larger T i / T e may result in larger propagation speeds and the critical flow velocity for the existence of steady solitons increases with increasing T i / T e values. The nonlinear solutions for various T i / T e values may be characterized by an effective Mach number. For T i / T e ≫ 1 the hot ions and cold electrons shall be described by the kinetic and fluid models, respectively, which may result in negative electric potentials opposite to the standard ion acoustic solitons. Comparisons between the model calculations and observations are made. [ABSTRACT FROM AUTHOR]

The crossing of two spatially smoothed laser beams amounts to the crossings of a large number of speckles. The energy transfer between two of these speckles is mediated by laser induced electron/ion density ripples that act as a Bragg grating. In a weakly Landau-damped plasma, this ion acoustic wave (IAW) may propagate from one crossing region to another, hence perturbing the local electron/ion grating [Oudin et al. Phys. Rev. Lett. 127, 265001 (2021)] even without phase shift between IAWs. In this paper, we investigate how the phase-shifted IAWs generated at the speckle scale interfere and affect the overall energy exchange. To this aim, we perform 2D particle-in-cell simulations with in-phase and out-of-phase Gaussian beams. In the latter situation, which better matches a smoothed laser beam, we find that the destructive interferences between the ion waves significantly reduce the energy exchange compared to the plane wave case. Additional 2D particle-in-cell simulations with random phase plate smoothed laser beams confirm the relevance of this effect in carbon plasma. A second effect is that cross-beam energy transfer (CBET) inhibition persists in strongly damped plasmas when the speckle radius is comparable with the IAW damping distance. There, the reduction in the IAW amplitude is attributed to the smallness of the speckle's envelop. These results are supported by a simple model that analytically estimates the CBET and clearly shows that neglecting the inhomogeneities in the laser intensity would usually lead to an overestimate of the energy exchange. [ABSTRACT FROM AUTHOR]

The interstellar medium (ISM) of star-forming galaxies is magnetized and turbulent. Cosmic rays (CRs) propagate through it, and those with energies from ~ GeV - TeV are likely subject to the streaming instability, whereby the wave damping processes balances excitation of resonant ionic Alfvén waves by the CRs, reaching an equilibrium in which the propagation speed of the CRs is very close to the local ion Alfvén velocity. The transport of streaming CRs is therefore sensitive to ionic Alfvén velocity fluctuations. In this paper we systematically study these fluctuations using a large ensemble of compressible MHD turbulence simulations. We show that for sub-Alfvénic turbulence, as applies for a strongly magnetized ISM, the ionic Alfvén velocity probability density function (PDF) is determined solely by the density fluctuations from shocked gas forming parallel to the magnetic field, and we develop analytical models for the ionic Alfvén velocity PDF up to second moments. For super-Alfvénic turbulence, magnetic and density fluctuations are correlated in complex ways, and these correlations as well as contributions from the magnetic fluctuations sets the ionic Alfvén velocity PDF. We discuss the implications of these findings for underlying "macroscopic" diffusion mechanisms in CRs undergoing the streaming instability, including modeling the macroscopic diffusion coefficient for the parallel transport in sub-Alfvénic plasmas. We also describe how, for highly-magnetized turbulent gas, the gas density PDF, and hence column density PDF, can be used to access information about ionic Alfvén velocity structure from observations of the magnetized ISM. [ABSTRACT FROM AUTHOR]

In this paper, the problem of nonlinear ion-acoustic (IA) solitary waves in an electron-ion plasma is analyzed, assuming electrons obey the κ -Gurevich distribution. The density of adiabatically trapped suprathermal electrons is derived from a physically relevant distribution describing such electrons. As an application, the modified Korteweg-de Vries (mK-dV) equation considering the κ -Gurevich electron density is derived. The study has revealed that the main properties (phase velocity, amplitude, and width) of small IA waves are significantly influenced by trapped suprathermal electrons. We have found that as electron suprathermality increases in plasma (i.e., as electrons move far away from their Maxwellian trapping), both amplitude and width of IA soliton decreases. Our study revealed that the IA soliton energy decreases when electrons move far from their Maxwellian trapping. Studying solitary ion acoustic waves may allow us to gain a deeper understanding of space where fast superthermal electrons are present along with ions (e.g. Earth's auroral region, Jupiter magnetosphere). [ABSTRACT FROM AUTHOR]

In this paper, we perform stability and bifurcation analysis of ion‐acoustic waves in a plasma consisting of warm adiabatic positive and negative ions, evolving against a uniform background of isothermal electrons. The model consists of two nonlinear ordinary differential equations incorporating ion temperature, negative ion concentration and negative‐to‐positive ion mass. We derive the normal form of bifurcation which allows the determination of travelling wave solutions for various regions in the parameter space of warm negative ion plasmas. It is shown that negative/positive ion temperature broadens the region prior to the saddle‐node bifurcation, thereby allowing the propagation of solitary and supernonlinear periodic waves. For a range of ion mass ratio and ion temperature, we find different existence domains of stability region, and examine the occurrence of transcritical bifurcation as a function of various plasma parameters. Further, we perform a numerical phase portrait analysis of the complex system including homoclinic orbits, nonlinear periodic and super nonlinear periodic orbits. The effects of ion mass ratio and ion temperature on the characteristic of these nonlinear structures are discussed in detail. Our results are relevant to wave solutions in laboratory and space plasmas, where simultaneous presence of warm negative/positive ions are observed. [ABSTRACT FROM AUTHOR]

We derive a set of self-consistent marginally stable states for a system of ion-cyclotron waves propagating parallel to the large-scale magnetic field through a homogeneous proton–electron plasma. The proton distributions and the wave dispersions are related through the condition that no further ion-cyclotron resonant particle scattering or wave growth/damping may take place. The thermal anisotropy of the protons in these states therefore defines the threshold value for triggering the proton-cyclotron anisotropy instability. A number of recent papers have noted that the anisotropy of solar wind protons at 1 AU does not seem to be limited by the proton-cyclotron anisotropy threshold, even at low plasma beta. However, this puzzle seems to be due solely to the estimation of this anisotropy threshold under the assumption that the protons have a bi-Maxwellian distribution. We note that bi-Maxwellian distributions are never marginally stable to the resonant cyclotron interaction, so these estimates do not represent physically valid thresholds. The threshold anisotropies obtained from our marginally stable states are much larger, as a function of proton parallel beta, than the bi-Maxwellian estimates, and we show that the measured data remains below these more rigorous thresholds. Thus, the results of this paper resolve the apparent contradiction presented by the solar wind anisotropy observations at 1 AU: the bi-Maxwellian anisotropies are not rigorous thresholds, and so do not limit the proton distributions in the solar wind. [ABSTRACT FROM AUTHOR]

Internal solitary waves propagation perturbing the sound velocity field, causes fluctuations in the sound field. This paper proposes to process the sound pressure data by the Product of the Slope and the even square of the Difference between two points of the acoustic parameter-time curve (PSD). The PSD processed data are processed to time-frequency analysis to extract the frequencies of the fluctuations in sound field. In this paper, numerical simulations and laboratory experiments are carried out on the process of internal solitary wave propagation in the sound field, and the characteristics of the sound field perturbation by internal solitary waves of different amplitudes are investigated. Results are both showing that the method can extract the dominant frequency of fluctuations in the sound field caused by internal solitary waves in real conditions. The method can be applied to the inversion of internal solitary wave phase speed which related to other parameters such as amplitude and characteristic width by theory. It is anticipated that this method can help realize the monitoring of internal solitary waves using acoustic paths. • A Product of Slop and Difference (PSD) method used to extract the fluctuation of sound field. • Considering the effects on sound field with internal solitary wave propagating. • The method to extract fluctuations in the sound field is validated by experiments in the tank. • Both simulation and experiments results showed the method can be applied in inversion of internal solitary waves. [ABSTRACT FROM AUTHOR]

The dispersion relation and the speed of linear magnetosonic wave are given in the present paper. Furthermore, an arbitrary amplitude nonlinear magnetosonic solitary wave is studied. It is found that the amplitude of the magnetosonic solitary wave cannot be larger than a critical value. It is found that the maximum speed of the magnetosonic solitary wave is about 1.24 times that of the Alfvén wave speed when the magnetic field is sufficiently strong so that the magnetic pressure is much larger than the fluid pressure. On the other hand, the maximum perturbed magnetic field is just equal to the external magnetic field if the magnetic pressure is much larger than the fluid pressure. It suggest that the variation regime of the perturbed magnetic field is (0 , B 0) , while the variation regime of the speed of magnetosonic solitary wave is (v A , 1.24 v A) in the upstream and downstream regions of the Venusian bow shock. Here B 0 and v A represent the background magnetic field and the Alfvén wave speed, respectively. [ABSTRACT FROM AUTHOR]

Based on the observation from Van Allen Probes, we report an event of intense and simultaneous electromagnetic ion cyclotron (EMIC) and chorus waves inside the low‐density plasmatrough. By calculating the scattering rates and performing the diffusion simulations, we for the first time evaluate the combined scattering of suprathermal electrons by EMIC and chorus waves in the low‐density plasmatrough. Landau acceleration of suprathermal electrons by EMIC waves is mainly restricted at large pitch angles while their scattering loss by chorus waves occurs at small pitch angles well below 90°. When EMIC and chorus waves are simultaneously present, the scattering of suprathermal electrons by the two waves is very different from that by each type of waves alone. EMIC waves play a complementary role in the scattering of suprathermal electrons by chorus waves, which facilitate the scattering of suprathermal electrons over all pitch angles. The near‐equatorially minoring suprathermal electrons are firstly scattered toward intermediate pitch angles by EMIC waves and further toward the loss cone by chorus waves. Our results highlight the complementary role of different types of magnetospheric waves in the suprathermal electron scattering, which potentially have vital implications for the dynamics of suprathermal electrons in the planetary magnetosphere. Plain Language Summary: Electromagnetic ion cyclotron (EMIC) waves and chorus waves are two natural and common electromagnetic emissions controlling the electron dynamics in the terrestrial magnetosphere. Although the scattering of suprathermal electrons (∼0.1 to tens of keV) by EMIC or chorus alone has been analyzed, their combined scattering remains unclear. In this paper, we report an event of chorus and EMIC waves simultaneously observed by Van Allen Probes inside the low‐density plasmatrough. For the first time, the combined scattering of suprathermal electrons by chorus and EMIC waves in the low‐density plasmatrough is evaluated through the scattering rate calculation and the Fokker‐Plank simulation. The numerical simulations demonstrate that EMIC waves play a complementary role in the scattering of suprathermal electrons by chorus waves, which facilitates the scattering of suprathermal electrons over all pitch angles. These results promote our understanding of the collaborated effect of different types of magnetospheric waves in controlling the suprathermal electron dynamics. Key Points: Intense chorus and electromagnetic ion cyclotron (EMIC) waves are simultaneously observed outside the plasmasphere by Van Allen ProbesThe combined scattering of suprathermal electrons by chorus and EMIC waves in the low‐density plasmatrough is evaluated for the first timeThe addition of Landau resonance by EMIC waves makes a complement to the scattering of suprathermal electrons by chorus waves [ABSTRACT FROM AUTHOR]