Electrostatic Disturbances Research Articles

Nonlinear propagation of ion-acoustic waves along with their bifurcation analysis in a negative ion plasma in the presence of quartic nonlinearity

In this article, the propagation of ion-acoustic shock and periodic waves along with their dynamical analysis around the supercritical values is studied in a (1 + 1)-dimensional collisionless negative ions plasma system comprising of inertia SF 6− with mass m−i and temperature T−i, inertia K+ with mass m+i and temperature T+i and inertialess non-extensive distributed electrons. By considering the appropriate starching coordinates and expansion of perturbation quantities, the Burgers-type equation with quartic nonlinearity is derived. Using the traveling wave transformation, a planar dynamical system is formed. The phase portrait is drawn and the associated nonlinear waves are analyzed. The research presented could be beneficial for understanding and forecasting localized electrostatic disturbances in the F- and D-layers of Earth's ionosphere as well as for guiding future experimental investigations in plasma laboratories.

On the characteristics of DA shock waves in a polarized electron-depleted plasma with a mixed nonextensive high energy-tail ion distribution

A first theoretical attempt is made to understand the characteristics of dust acoustic shock waves (DASWs) in a polarized electron-depleted plasma with a mixed nonextensive high energy–tail ion distribution and to examine the impact of the generalized nonthermal polarization force on DASWs in an electron-depleted dusty plasma. First, a short numerical investigation illustrating the behavior of the mixed nonextensive high energy–tail (or Cairns–Tsallis) ion distribution and the domain of validity of its two parameters (q and [Formula: see text]) is carried out. Next, the generalized nonthermal polarization acting on dust grain in electron-depleted dusty plasma is determined within the context of Tsallis’ statistical mechanics. The behavior of this generalized polarization force is significantly affected by the nonextensive character of the nonthermal ions. Specifically, we have shown that, for both space and experimental dusty plasmas, the magnitude of the polarization force (in the case where [Formula: see text]) decreases as the nonextensivity of the nonthermal ions becomes significant. As an application, we have analyzed the changes caused by the nonthermal nonextensive polarization force on the main characteristics of DASW (viz. phase velocity, polarity, amplitude, width, etc.). Numerical results showed that our plasma model supports rarefactive and compressive DASWs that are significantly affected by the effects of nonthermal ion nonextensivity and polarization force. In particular, we have shown that for large values of the nonthermal parameter [Formula: see text], the increase in q allows the transition from rarefactive to compressive DASW structures. The present theoretical investigation is helpful to fully understand electrostatic disturbances in space and experimental dusty plasmas.

Dust Acoustic Dromions in a Magnetized, Five-Component Cometary Plasma

A study of the characteristics of dust acoustic dromions (DADs), described by the Davey–Stewartson-I (DS-I) equations, in a five-component cometary plasma has been carried out, the five components being negatively charged dust particles, superthermal electrons (hotter solar and colder cometary electrons), and positively charged hydrogen and oxygen ions. It is found that the parametric region for the existence of dromions is influenced by the superthermality of both ions and electrons. The effects of various physical parameters, such as the superthermality, strength of the magnetic field, and concentrations of hydrogen and oxygen ions and cometary electrons on the propagation of the DADs, have been studied. The results of the present investigation could be useful for understanding some of the nonlinear features of localized electrostatic disturbances in a cometary environment. The study also proves that dromions can propagate in these plasmas.

On the experimental and theoretical calculations of rotameric conformations of a new Schiff base derived from amantadine

Herein, the condensation of amantadine with the aldehyde piperonal resulted in a new Schiff base (1). This molecule was fully characterized by elementary analysis, infrared (IR), ultraviolet-visible (UV-Vis), 13C, 1H nuclear magnetic resonance (NMR) and high-resolution mass spectroscopy, logP (logarithm of partition coefficient), as well as single-crystal X-ray diffraction (SCXRD). The crystal structure crystallizes in the triclinic P1¯ space group with only one molecule of the Schiff base in the asymmetric unit, presenting the adamantane ring disordered over two positions. The crystal self-assembly is stabilized by weak interactions, such as analyzed by Hirshfeld surface. Using the DFT calculation, an energy barrier of 9.075 kcal.mol−1 was found between the two complementary conformations observed experimentally to the adamantane group. The computed infrared spectra (in vacuum and solution) are in good agreement with the experimental data. The energy of the HOMO orbitals was also calculated, in which energy values ​​range -7.4030–7.6027 eV, while LUMO orbitals are in the range of -0.3610–0.5717 eV, in which the polar solvents promoted greater stabilization in the border orbitals. The chemical potential (μ) from 3.467 to 3.520 eV indicate that the structure is stable. The magnitude of the chemical hardness (η) [6.934–7.041 eV] suggests the resistance to deformation of the electronic cloud over small electrostatic disturbances, showing that the system is not very polarizable. This result can be useful to further studies to investigate the coordination ability of compound 1 with hard metal ions.

Electron-acoustic waves by (modified) Zakharov–Kuznetsov equation and their multi-dimensional instability in the auroral zone

The feature of electron-acoustic waves (EAWs) in a magnetized plasma composed of stationary ions, nonthermal electrons and cold electron fluids is presented. The Zakharov–Kuznetsov (ZK) equation and modified Zakharov–Kuznetsov (mZK) equation are derived via reductive perturbation technique. The solitary wave solutions of ZK and mZK equations and the corresponding growth rates of multi-dimensional instability are given via small k perturbation method. The instability criterion and growth rate rely on obliqueness, magnetic field strength, temperature and density ratios of the hot-to-cold electron species, nonthermal parameter and direction cosines. It is apparent that, in the dayside auroral zone, there only exists negative potential solitary waves, and when the external magnetic field is larger and obliqueness is smaller, EAWs by mZK equation are more unstable than that by ZK equation. The results are beneficial to understand different nonlinear characteristics of unstable electrostatic disturbances in laboratory and space plasmas.

Electron-Acoustic Solitons in Magnetized Collisional Nonthermal Plasmas

The properties of obliquely propagating dissipative electron-acoustic solitary waves (OPdEASWs) have been investigated in a magnetized collisional superthermal plasma consisting of inertial cold electrons, inertialess hot electrons featuring κ-distribution, and static ions via the fluid dynamical approach. Using the reductive perturbation technique, a nonlinear Schamel equation that governs the nonlinear features of OPdEASWs is obtained. The solitary wave solution of the Schamel equation is used to examine the basic features of small but finite amplitude OPdEASWs in such a magnetized collisional superthermal plasma. The basic features (width, amplitude, speed, and so on) of OPdEASWs are found to be modified by the different plasma configuration parameters, such as the superthermality index, obliquity angle, collisional parameter, trapping parameter, and external magnetic field. The nature of electrostatic disturbances, that may propagate in different realistic space and laboratory plasma systems (e.g., in Saturn ring), is briefly discussed.

Damped dust‐ion‐acoustic solitons in collisional magnetized nonthermal plasmas

AbstractA multispecies magnetized collisional nonthermal plasma system, containing inertial ion species, noninertial electron species following nonthermal ‐distribution, and immobile dust particles, is considered to examine the characteristics of the dissipative dust‐ion‐acoustic soliton modes, theoretically and parametrically. The electrostatic solitary modes are found to be associated with the low‐frequency dissipative dust‐ion‐acoustic solitary waves (DIASWs). The ion‐neutral collision is taken into account, and the influence of ion‐neutral collisional effects on the dynamics of dissipative DIASWs is investigated. It is reported that most of the plasma medium in space and laboratory are far from thermal equilibrium, and the particles in such plasma system are well fitted via the ‐nonthermal distribution than via the thermal Maxwellian distribution. The reductive perturbation approach is adopted to derive the damped KdV (dKdV) equation, and the solitary wave solution of the dKdV equation is derived via the tangent hyperbolic method to analyse the basic features (amplitude, width, speed, time evolution, etc.) of dissipative DIASWs. The propagation nature and also the basic features of dissipative DIASWs are seen to influence significantly due to the variation of the plasma configuration parameters and also due to the variation of the supethermality index in the considered plasma system. The implication of the results of this study could be useful for better understanding the electrostatic localized disturbances, in the ion length and time scale, in space and experimental dusty plasmas, where the presence of excess energetic electrons and ion‐neutral collisional damping are accountable.

Electromagnetic wave transparency of X mode in strongly magnetized plasma

An electromagnetic (EM) pulse falling on a plasma medium from vacuum can either reflect, get absorbed or propagate inside the plasma depending on whether it is overdense or underdense. In a magnetized plasma, however, there are usually several pass and stop bands for the EM wave depending on the orientation of the magnetic field with respect to the propagation direction. The EM wave while propagating in a plasma can also excite electrostatic disturbances in the plasma. In this work Particle-In-Cell simulations have been carried out to illustrate the complete transparency of the EM wave propagation inside a strongly magnetized plasma. The external magnetic field is chosen to be perpendicular to both the wave propagation direction and the electric field of the EM wave, which is the X mode configuration. Despite the presence of charged electron and ion species the plasma medium behaves like a vacuum. The observation is understood with the help of particle drifts. It is shown that though the two particle species move under the influence of EM fields their motion does not lead to any charge or current source to alter the dispersion relation of the EM wave propagating in the medium. Furthermore, it is also shown that the stop band for EM wave in this regime shrinks to a zero width as both the resonance and cut-off points approach each other. Thus, transparency to the EM radiation in such a strongly magnetized case appears to be a norm.

Design of a Fuzzy Adaptive Sliding Mode Control System for MEMS Tunable Capacitors in Voltage Reference Applications

Micro electro mechanical system (MEMS) tunable capacitors (TC) are major elements in ac voltage reference sources (VRS). Physical parametric uncertainties, external electrostatic disturbance, and measurement noise malfunction their operation and ruin the preciseness of the VRS output voltage. Our objective problem is the design of a controller to cope with the mentioned parametric uncertainties, noise, and disturbance. Our applied method is the design and employment of a proportional integral fuzzy adaptive sliding mode controller (FASMC). Both terms of matched and unmatched uncertainties as well as external disturbance and measurement noise are all addressed in this article to generate a stable VRS output for the first time. Not only does this article contribute to the employment of a FASMC to enhance robustness in the drive of the capacitor, but also it benefits the reduction of the chattering effect due to fuzzy regulation in the switching term of the control law. Moreover, the automatic fuzzy adjustment in the controller, which is used for estimation of the coefficients in the sliding surface error dynamical equation, facilitates the specification of those coefficients, which can be time consuming in simulation affairs. Clarifying the importance of the proposed fuzzy adaptive sliding mode controller, this article reviews some previous controllers for MEMS TC in comparison with the proposed fuzzy controller, demonstrating its enhancement in comparison with previous schemes.

Multi‐dimensional instability of electrostatic solitary waves in a warm multi‐ion dust plasma

AbstractStudy of dust ion acoustic waves in a magnetized dusty plasmas composed of negatively or positively charged static dust, positive and negative ions, as well as kappa distribution electrons is presented. The Zakharov–Kuznetsov (ZK) equation is derived via reductive perturbation technique. The solitary wave solution of ZK equation is given and the multi‐dimensional instability of these solitary waves is investigated via small k perturbation method. The instability criterion and growth rate relying on obliqueness, superthermality, positive ion thermal pressure, relative ion number density, magnetic field strength, and direction cosines are discussed for five cases. The results are beneficial to understand different nonlinear characteristics of unstable electrostatic disturbances in laboratory and space plasmas.

Cylindrical and Spherical Electro-acoustic Waves in a Strongly Coupled Cryogenic Quantum Plasma

The propagation of the nonplanar (both cylindrical and spherical) electro-acoustic waves, particularly ion-acoustic waves in a strongly coupled cryogenic electron-ion plasma has been studied utilizing the generalized quantum hydrodynamic model applicable for the cryogenic situation. The Korteweg–de Vries and Burgers equations are derived by adopting the reductive perturbation technique. The basic features (e.g., phase speed, amplitude, and width, etc.) of the ion-acoustic solitary and shock waves, are identified by analyzing the stationary solitary, and shock wave solutions of the Korteweg–de Vries and Burgers equations, respectively. It is found that the basic characteristics of the IA nonlinear structures in non-planar geometry are significantly modified by the effects of the ratio of plasma particle number densities, the Fermi temperature and pressure of electrons, the viscous coefficient, etc. The results of this theoretical investigation may be useful in describing the physics of the ion-acoustic nonlinear features of the localized electrostatic disturbances in quantum cryogenic plasmas (viz. laser-produced plasmas, super-intense laser-dense matter experiments, etc.).

Propagation of ion-acoustic localized mode excitations and their modulational instability analysis in electron–positron–ion plasmas

The modulational instability of ion-acoustic waves (IAWs) in an unmagnetized multicomponent plasma is investigated, including a hot positrons, hot isothermal electrons and cold ions. Employing the reductive perturbation technique, the nonlinear Schr $$\ddot{o}$$ dinger equation (NLSE) is derived. The effects of positron concentration and temperature ratio of electron to positron significantly modify the modulational instability and its growth rate. Results show that increasing the strength of these parameters leads to localization of IAWs. Further, the exact traveling wave solutions are studied using a modified extended tanh function method. The relevance of theoretical results may be beneficent in understanding the localized electrostatic disturbances in space and astrophysical situations where electron–positron–ion plasmas are present.

Electrostatic Disturbances of Aerosol Atmospheric Plasma: Beaded Lightning

Numerous sources produce the ionization impact on the planetary atmosphere. The tropospheric cloudiness therewith is originated at such altitudes, which coincide with places of the maximum of the atmospheric ionization that caused by space radiation. Components of cosmic radiation, penetrating down to the stratospheric and tropospheric altitudes, produce in the first place the ionization of aerosols that brings to subsequent amplifying the activity of atmospheric vortices. The ionized aerosol constituent is of primary importance both in the initiation of plasma vortices and in the concentration of energy-mass by air vortices due to the humidity condensation. The ionization process is cascading, that causes the non-linear impact of penetrating rays, which amplifying with growing the air pollution. Various heterogeneities inside plasma subsystems provoke the random intensification of aperiodic electrostatic disturbances, which can exert a significant action on the development of vortices. Sometimes beaded lightning arises during thunderstorm. Using the approach of the Boltzmann kinetic equation, the characteristics of electrostatic oscillations for non-uniform plasma, are analytically derived. The analytical expressions are obtained for non-magnetized plasma. In the limits of the Earth’s atmosphere, these solutions are strictly applicable to the origination of electrostatic modulations along the lines of force of the geomagnetic field and approximately applicable in cases, when the impact of the Earth’s magnetic field is negligible. The explicit expressions are deduced both in the hot plasma approximation and in the cold plasma approximation. It is demonstrated that the formation of chain elements of discharge in hot inhomogeneous plasma is defined by the nonmonotonic distribution of charges and fields. At such conditions, the irregularities breaks up into a cellular structure.

On the interaction of nonlinear ion acoustic solitary waves in non-ideal plasma incorporated with Cairns-Gurevich distributed electrons

A rigorous theoretical study of the head-on collision (HoC) of two ion acoustic solitons in unmagnetized non-ideal plasmas containing warm fluid ions and Cairns-Gurevich distributed electrons is presented. The extended Poincare-Lighthill-Kuo (PLK) method is employed and coupled modified Kortweg-de Vries (mKdV) equations describing the system are derived. The nonlinear evolution equations for the colliding solitons, the corresponding phase shifts and trajectories of the two solitary waves are calculated and analyzed numerically. It is found that the process of solitons collision strongly depends on the hybrid nonthermal trapped electron parameter. Shortly, it is detected that the collision phase shifts increase with the increment of the nonthermal parameter in the case of ideal plasma. Though, for ideal plasma case, the phase shifts are constant and larger than that of non-ideal case. The gained results could be useful in clarifying the requisite features of localized electrostatic disturbance in the Earth’s magnetosphere where such distribution exists.

Электростатические возмущения неоднородной аэрозольной плазмы и устойчивость атмосферных вихрей

Электростатические возмущения неоднородной аэрозольной плазмы и устойчивость атмосферных вихрей

Nonlinear Dynamics in Strongly Coupled Quantum Plasma

The properties of cylindrical and spherical modified ion-acoustic waves in a strongly coupled plasma (containing strongly correlated non-relativistic ions, weakly correlated relativistic (both non-relativistic and ultra-relativistic) electron and positron fluids, and positively charged static heavy ions) are investigated theoretically. The restoring force is provided by the degenerate pressure of the electron and positron fluids, whereas the inertia is provided by the mass of ions. The positively charged static heavy ions participate only in maintaining the quasi-neutrality condition at equilibrium. By using reductive perturbation method, we have derived modified Burgers and Korteweg–de Vries equations. Their shock and solitary wave solutions are also numerically analyzed to understand the localized electrostatic disturbances. The basic features of modified ion-acoustic shock and solitary waves are found to be significantly modified by the effects of degenerate pressure of electrons, positrons, and ion fluids, their number densities, and various charge states of heavy ions. It is also observed that the amplitude of these shock and solitary profiles are maximum for spherical geometry, intermediate for cylindrical geometry, and minimum for planar geometry. The present analysis can be helpful for understanding different degenerate and relativistic phenomena in dense astrophysical environments as well as laboratory plasma systems.

Obliquely propagating electron-acoustic solitary waves in magnetized plasmas: the role of trapped superthermal electrons

The properties of obliquely propagating electron-acoustic solitary waves (OPEASWs) have been investigated in a magnetized superthermal plasma (containing inertial cold electron species, inertialess electrons following Vasyliunas-Schamel distribution function, and static ions) via the fluid dynamical approach. The reductive perturbation technique is employed to derive the Schamel equation and the solitary wave solution of the Schamel equation is used to examine the basic features of small but finite amplitude OPEASWs in such a magnetized plasma in the presence of trapped k-superthermal hot electron population. The basic features (width, amplitude, speed, etc.) of OPEASWs are found to be significantly modified by the different plasma configuration parameters, such as plasma superthermality, obliqueness, the particle trapping effect, and external magnetic field effect. The nature of electrostatic disturbances, that may propagate in different realistic space and laboratory plasma systems (e.g., in Saturn ring), is briefly discussed.

Supramolecular protection-mediated one-pot synthesis of cationic gold nanoparticles

Despite the extended use of cationic gold nanoparticles (AuNPs) in biomedical applications, direct one-pot synthesis of AuNPs with tunable size in aqueous media is limited due to the deleterious electrostatic attraction between AuCl4-anions and positively charged ligands. This paper describes the one-pot synthesis of cationic gold nanoparticles with size tunability based on host-guest chemistry. As the host molecule, cucurbit[7]uril inhibits self-aggregation in aqueous solution by threading positively charged guest ligands, which provides a shielding effect on the ligands. Reduction of the mixtures by directly adding NaBH4 generates cationic AuNPs with narrow size distributions. Furthermore, their potential in biomedical applications is demonstrated by siRNA transfection experiments. This approach relying on supramolecular-mediated interactions may provide new insights into organic/inorganic reactions that involve electrostatic disturbance.

Addressing the effects of background plasma and wake formation on nanosatellites with electric propulsion using a 3D Particle In Cell code

3D-PIC (Particle In Cell) simulations were performed to emulate the dynamics and collection of plasma particles onto the surface of the UWE-IV, a satellite of miniaturized dimensions (CubeSat) launched in 2018. We review the electrostatic potential, currents collected and plasma disturbances of the CubeSat and characterize them by numerical simulation over Low Earth Orbits (LEO), in two general cases: as a passive satellite and with active thrusters without regard of neutralization units. During one orbital period the passive CubeSat drives an isotropic impingement of plasma electrons, that (because their higher mobility regarding ions) govern a negative surface potential. However, by the time-evolution of the charge sheath, we relate that potential barriers may be forming around the satellite that can reduce the collection of electrons over spacecraft surfaces. When thrusters are fired, spacecraft becomes more negatively charged than for a passive satellite, and their potential energy E sc is about hundreds of times larger than the ambient ion flowing energies, E i . In this case, ion density maps of ambient oxygen ( O + ), show particles fill in the ion void (wake) zone due to bare electrostatic attraction by a (growing) negative satellite potential. The experiment was repeated in different orbit altitudes with varying plasma densities, showing that in space zones with greater concentration of plasma ions, the satellite potential is less negative, ultimately linked to this near-wake ion-focusing collection. Thus, we conclude that if thrusters operate in LEO altitudes, where the relatively higher plasma concentrations are (equatorial orbits of 300–500 km), large negative potentials can be avoided due to the natural rule of ambient ion dynamics. This study can be important for operations of future miniaturized satellites using this type of thruster technologies.

Dissipative electron-acoustic solitons in a cold electron beam plasma with superthermal trapped electrons

The linear and nonlinear properties of high-frequency electron-acoustic (EA) solitons are investigated in multi-component dissipative plasma with a cold beam electron fluid, the Schamel-kappa distributed hot trapped electrons, and stationary ions. The linear phase speed is found to be modified significantly due to variations in dissipative, superthermality, and beam speed parameters. The impact of dissipation (cold electron-to-neutrals collisions) and superthermality on the characteristics of electron acoustics waves (EAWs) is elaborated. The multiple scale expansion method is employed to derive time-varying Schamel equation for small-amplitude electrostatic potential disturbances, carrying dissipative processes as well. The variations in superthermality, and beam speed parameters have been found to strongly impact the profiles of dissipative solitons obtained through numerical time evolution of Schamel equation. The significance of the work lies in the fact that positive potential electron acoustic solitons are sustained, which correspond to holes (or humps) in the cold (hot) electron number density. As trapping is a nonlinear phenomenon, so its impact on these solitary dissipative structures have also been highlighted with suitable application parameters. This study should be beneficial for understanding nonlinear structures reported in the dayside auroral zone and other regions of the magnetosphere.