Nonuniform Magnetoplasma Research Articles

Investigation of electromagnetic oscillations and their instabilities in a nonuniform quantum electron-positron magnetoplasma interacting with a short pulse laser

Investigation of electromagnetic oscillations and their instabilities in a nonuniform quantum electron-positron magnetoplasma interacting with a short pulse laser

Propagatory dynamics of electromagnetic drift waves in inhomogeneous spin degenerate compact objects plasmas

A theoretical analysis is carried out to investigate the dynamics of electromagnetic drift modes in non-uniform spin quantum magnetoplasmas found in degenerate compact objects. General dispersion relations are derived using spin quantum hydrodynamic equations, Poisson equation, and Maxwell equation, with and without ion inertial effects. The effects of quantum spin magnetization, Bohm potential, and density inhomogeneity on the dispersion of electromagnetic drift modes are explored numerically. The advancing theoretical analysis demonstrated herein has strong correlations and consistencies with the dynamic growth of compact astrophysical objects and their surrounding atmospheres, such as black holes, white dwarfs, and dense molecular clouds.

Rayleigh-Taylor instability in an adiabatic-radiative rare plasma

Considering the particle nature of photons, the impact of electromagnetic radiation pressure is examined on the Rayleigh-Taylor instability (RTI) in a non-uniform rare magnetoplasma. For low-density and high-temperature rare plasma, the RTI with radiation pressure is revisited in the adiabatic limit. The growth rate conditions and propagating modes are derived using the framework of a developed fluid model. For specific values of ion temperature, the cut-off values of propagation of the fringing instability is found to be temperature dependent. A numerical comparison of the present results with previous work Maryam N, Rozina C and Ali S (2021, IEEE Transactions on Plasma Science 49 1072–1078) is displayed in table 1. It is found that the radiative acoustic speed is increased due to electromagnetic radiation pressure in rare plasmas as compared to radiative acoustic speed in dense plasmas. However, the growth rate of RTI increases comparatively as function of radiation pressure in rare plasmas. The present findings reveals that the consequences of RTI are remarkably concerned with the choice of electromagnetic radiation pressure either in dense (astrophysical) or rare (laboratory) plasmas. These findings are relevant to the observations of long-lived irregularities for explaining the gravitational instability in laboratory plasmas, e.g. in fusion devices like tokamaks.

Ion velocity shear‐induced drift wave and momentum transport in non‐Maxwellian magnetoplasma flows

AbstractWe have investigated the diamagnetic flow in a non‐uniform partially ionized plasma with non‐Maxwellian electron population to explain the dynamics of ion velocity shear‐induced low‐frequency drift mode and associated instabilities. The dispersion relations are found, and instability threshold conditions are pointed out along with ion‐parallel momentum transport due to drift motion with relative phase shift of fluctuating quantities in a non‐conservative system. The real frequencies and instability growth rates are studied numerically and illustrated for typical space and laboratory plasmas. This study should be useful in understanding some aspects of low‐frequency time‐delayed perturbations with sheared flow leading to drift instabilities and cross‐field parallel ion momentum transport in nonuniform magnetoplasmas containing a non‐Maxwellian electron population.

Shear flow driven counter rotating vortices in non-uniform magnetoplasmas with warm ions and generalized (r, q) distributed electrons

We have analyzed the linear and nonlinear finite amplitude coupled drift ion acoustic waves in a spatially non-uniform plasma consisting of warm ions in the presence of sheared ion flow and electrons whose distribution in high and low phase space density regions is governed by two spectral indices, namely, r and q respectively. It has been found that stationary solution of the nonlinear equations in the form of a counter rotating vortex can be obtained for a particular choice of the equilibrium potential profile. It has been found that the double spectral indices r and q make a very pronounced effect on the formation and size of the counter-rotating vortices in spatially inhomogeneous plasmas and the applicability of the current study in understanding the wave phenomena with reference to space plasmas is also discussed.

Quantum Rayleigh-Taylor instability: the exchange and correlation effects of electron

Using quantum magneto-hydrodynamic (Q-MHD) model, a set of governing equations is presented for a Rayleigh–Taylor (RT) instability in an extremely dense plasma. A local dispersion relation is derived for the RT mode in a magnetized plasma, where the effects of exchange and correlation for electrons are taken into account. The dispersion relation is then analyzed both analytically as well as numerically. It is found that inclusion of the exchange and correlation effects modifies the growth rate of the RT instability and gives the quantum RT mode a stabilizing effect. The linear growth rate of the mode is found to be localized due to Bohm potential and the potential associated with the exchange and correlation. It is estimated that results might be useful in interpreting the dynamical properties of a quantum nonuniform magneto-plasma system on industrial phenomena such as ultra-small electronic devices as well as natural phenomena such as astrophysical compact objects (white dwarfs/neutron stars).

Electromagnetic Viscous-Resistive-Drift-Wave Instability in Burning Plasma

Drift wave instabilities (DWI) might be take a part for anomalous transport in modern day tokamaks due to contributions of edge turbulence and zonal flows. Experimentally, it is found that micro-level turbulence (associated with two-fluid dynamics) braced with macro-level (associated with single-fluid dynamics) magnetohydrodynamics-type processes. In this paper, additional two-fluid effect viz. ion viscosity on the electromagnetic (EM) linear resistive drift wave instability is analyzed by using a two-fluid MHD model. A modify dispersion relation for EM drift modes in a nonuniform magnetized plasma is derived, taken into account equilibrium pressure gradients, effect of finite ion-sound gyro-radius associated with electron–ion decoupling and viscous effect due to ions. The dispersion relation is then analyzed both analytically as well as numerically. It is shown, how additional two-fluid effects modify the growth rate for DWI in different regimes. The standard resistive drift-Alfven mode is reproduced in the cold ion case. Moreover, it is estimated that these effects provide the possibility of novel effects on EM instabilities in a nonuniform magnetized plasma. The results should be useful in the interpretation of EM fluctuations in nonuniform magneto-plasmas in which resistivity is a key element in calculations of dissipative drift instabilities.

Resistive drift instabilities for thermal and non-thermal electron distributions in electron-ion plasma

Local dispersion relations for resistive drift mode in a nonuniform magnetize plasma are derived for thermal and non-thermal distribution of electrons. The coupled mode equations are obtained by using Braginskii's transport equations for ions and electrons with thermal as well as non-thermal (Cairns and kappa) distribution for electrons. The dispersion relations are then analyzed both analytically as well as numerically for all distributions. It is found that growth rate is highest for Maxwellian, Intermediate for kappa and lowest for Cairns distribution. It has been found that increasing values of Γ (which estimate population of non-thermal electrons) for Cairn distributed electrons are able to stabilize the mode. Furthermore, increasing the values of κ (which is spectral index) for the kappa distributed electrons have destabilizing effects on the mode. The result might be useful in the interpretation of electromagnetic fluctuations in nonuniform magneto-plasma in which resistivity is a key element in calculation of drift instabilities in the presence of thermal or nonthermal electron distributions, such systems are extensively observed in laboratory as well as space plasma.

Electrons in regions of high phase density exhibit uncanny traits in the study of linear and nonlinear drift waves in spatially non-uniform magnetoplasmas

Linear and nonlinear waves are examined on the ion time scale in a spatially inhomogeneous plasma having electrons that follow product bi (r,q) distribution. It has been shown that the linear dispersion relation for product bi (r,q) distribution undergoes appreciable changes as opposed to the one for the Maxwellian electrons. It has been found that the drift wave frequency is highest for flat-topped distribution, whereas it is lowest for the spiky distribution. It has been found that the drift solitary wave with flat-topped distribution (i.e., r > 0) is one of a kind and exhibits peculiar characteristics. It has been shown that Maxwellian and kappa-like electrons cannot alter the nature of the electrostatic drift waves under consideration; however, the spiky electrons can. The results obtained here are general and can be applied to many regions of space plasmas where the satellite missions have reported the presence of electron distribution functions that show deviation from the Gaussian behavior.

Gestational Diabetes and Subsequent Risk of Albuminuria in Later Life Among US Women

Local dispersion relations for resistive drift mode in a nonuniform magnetize plasma are derived for thermal and non-thermal distribution of electrons. The coupled mode equations are obtained by using Braginskii's transport equations for ions and electrons with thermal as well as non-thermal (Cairns and kappa) distribution for electrons. The dispersion relations are then analyzed both analytically as well as numerically for all distributions. It is found that growth rate is highest for Maxwellian, Intermediate for kappa and lowest for Cairns distribution. It has been found that increasing values of Γ (which estimate population of non-thermal electrons) for Cairn distributed electrons are able to stabilize the mode. Furthermore, increasing the values of κ (which is spectral index) for the kappa distributed electrons have destabilizing effects on the mode. The result might be useful in the interpretation of electromagnetic fluctuations in nonuniform magneto-plasma in which resistivity is a key element in calculation of drift instabilities in the presence of thermal or nonthermal electron distributions, such systems are extensively observed in laboratory as well as space plasma.

Coupled ion acoustic and drift waves in magnetized superthermal electron-positron-ion plasmas

Linear and nonlinear coupled drift-ion acoustic waves are investigated in a nonuniform magnetoplasma having kappa distributed electrons and positrons. In the linear regime, the role of kappa distribution and positron content on the dispersion relation has been highlighted; it is found that strong superthermality (low value of κ) and addition of positrons lowers the phase velocity via decreasing the fundamental scalelengths of the plasmas. In the nonlinear regime, first, coherent nonlinear structure in the form of dipoles and monopoles are obtained and the boundary conditions (boundedness) in the context of superthermality and positron concentrations are discussed. Second, in case of scalar nonlinearity, a Korteweg–de Vries-type equation is obtained, which admit solitary wave solution. It is found that both compressive and rarefactive solitons are formed in the present model. The present work may be useful to understand the low frequency electrostatic modes in inhomogeneous electron positron ion plasmas, which exist in astrophysical plasma situations such as those found in the pulsar magnetosphere.

Modulation of drift-wave envelopes in a nonuniform quantum magnetoplasma

We study the amplitude modulation of low-frequency, long-wavelength electrostatic drift-wave envelopes in a nonuniform quantum magnetoplasma consisting of cold ions and degenerate electrons. The effects of tunneling associated with the quantum Bohm potential and the Fermi pressure for nonrelativistic degenerate electrons, as well as the equilibrium density and magnetic field inhomogeneities are taken into account. Starting from a set of quantum magnetohydrodynamic equations, we derive a nonlinear Schrödinger equation (NLSE) that governs the dynamics of the modulated quantum drift-wave packets. The NLSE is used to study the modulational instability (MI) of a Stoke's wave train to a small plane wave perturbation. It is shown that the quantum tunneling effect as well as the scale length of inhomogeneity plays crucial roles for the MI of the drift-wave packets. Thus, the latter can propagate in the form of bright and dark envelope solitons or as drift-wave rogons in degenerate dense magnetoplasmas.

Shear flow driven tripolar vortices in a nonuniform electron-ion magnetoplasma with non-Maxwellian electrons

A set of nonlinear equations governing the dynamics of finite amplitude drift-ion acoustic-waves is derived for sheared ion flows parallel and perpendicular to the ambient magnetic field in the presence of Cairns and Kappa distributed electrons. It is shown that stationary solution of the nonlinear equations can be represented in the form of a tripolar vortex for specific profiles of the equilibrium sheared flows. The tripolar vortices are, however, observed to form on a scale of the order of ion Larmor radius ρi which is calculated to be around a Kilometer for the plasma parameters found in the Saturn’s E-ring. The relevance of the present investigation in planetary environments is also pointed out.

Formation of solitary structures in uniform and nonuniform magnetoplasmas with superthermal electrons: a non-reductive perturbative approach

Electrostatic solitary structures are studied in uniform and nonuniform magnetoplasmas with superthermal electrons. In the linear analysis, the differences in the acoustic frequencies for Maxwellian, Cairns, and Kappa distributed electrons for both homogeneous and inhomogeneous plasmas are highlighted and discussed. It is shown that using the linear dispersion relation, nonlinear Zakharov-Kuznetsov (ZK) equation can be derived both for the homogeneous and inhomogeneous magnetoplasmas. The solution of the ZK equation is presented using the tangent hyperbolic method. It is found that the increasing magnetic field and the angle of propagation enhances the amplitude whereas the increasing number density mitigates the amplitude of the acoustic drift solitary wave. Furthermore, it is observed that the amplitude of the solitary structure is maximum for Cairns, intermediate for Maxwellian, and minimum for the Kappa distributed electrons. The results presented in this paper may be beneficial to understand the formation of electrostatic drift solitary waves in planetary environments where the nonthermal population of electrons are observed by various satellite missions.

Vortex formation in nonlinearly coupled modes in a magnetized quantum plasma

Linear and nonlinear properties of coupled modes in a magnetized quantum plasma in the presence of electron Fermi pressure are studied in a nonuniform magnetoplasma composed of electrons, ions, and extremely massive and negatively charged immobile dust grains. Stationary solutions of the nonlinear equations that govern the dynamics of coupled modes are presented. It is found that electrostatic dipolar vortex structure can form in such a plasma. The dipolar structures in dense plasmas are observed to be formed on a much shorter scalelength by comparison with their classical counterparts. It is found that the increasing Fermi temperature shortens the scalelength over which the nonlinear coherent structures are formed. The relevance of the present investigation with regard to the dense astrophysical plasmas is also pointed out.

Amplitude modulated drift wave packets in a nonuniform magnetoplasma

We consider the amplitude modulation of low-frequency, long wavelength electrostatic drift wave packets in a nonuniform magnetoplasma with the effects of equilibrium density, electron temperature and magnetic field inhomogeneities. The dynamics of the modulated drift wave packet is governed by a nonlinear Schrödinger equation. The latter is used to study the modulational instability of a Stokeʼs wave train to a small longitudinal perturbation. It is shown that the drift wave packet is stable (unstable) against the modulation when the drift wave number lies in 0<k<1/2 (1/2<k<1). Thus, the modulated drift wave packet can propagate in the form of bright and dark envelope solitons or as a drift wave rogon.

Diamagnetic drift instabilities in collisional non-uniform quantum dusty magnetoplasmas

AbstractDust-acoustic and dust-lower-hybrid diamagnetic drift wave instabilities have been examined in a collisional non-uniform quantum dusty magnetoplasma. The dust-acoustic drift instability arises through the Fermi degenerate pressure of electrons for a high-density plasma, while for a relatively low-density collisional quantum plasma and short wavelength consideration, the instability is dominated by the Bohm potential effect exciting a new quantum dust-acoustic wave. In the long-range wavelength limit, dust-lower-hybrid waves are found to be unstable because of the diamagnetic drift of magnetized ions. Various possible instability conditions are found for diamagnetic drift instability.

Stability analysis of self-gravitational electrostatic drift waves for a streaming nonuniform quantum dusty magnetoplasma

Using the quantum hydrodynamic model of plasmas, the stability analysis of self-gravitational electrostatic drift waves for a streaming non-uniform quantum dusty magnetoplasma is presented. For two different frequency domains, i.e., Ω0d≪ω&amp;lt;Ω0i (unmagnetized dust) and ω≪Ω0d&amp;lt;Ω0i (magnetized dust), we simplify the general dispersion relation for self-gravitational electrostatic drift waves, which incorporates the effects of density inhomogeneity ∇n0α, streaming velocity v0α due to magnetic field inhomogeneity ∇B0, Bohm potential, and the Fermi degenerate pressure. For both frequency domains, the effect of density inhomogeneity gives rise to real oscillations while the ions streaming velocity v0i as well as the effective electron quantum velocity vFe' make these oscillations propagate perpendicular to the ambient magnetic field. This oscillatory behavior of self-gravitational drift waves increases with increase in inhomogeneities and quantum effects while it decreases with increase in the gravitational potential. However, only for the unmagnetized case, the drift waves may become unstable under appropriate conditions giving rise to Jeans instability. The modified threshold condition is also determined for instability by using the intersection method for solving the cubic equation. We note that the inhomogeneity in magnetic field (equilibrium density) through streaming velocity (diamagnetic drift velocity) suppress the Jeans instability depending upon the characteristic scale length of these inhomogeneities. On the other hand, the dust-lower-hybrid wave and the quantum mechanical effects of electrons tend to reduce the growth rate as expected. A number of special cases are also discussed.

Guiding of a laser beam in collisional magnetoplasma channel

AbstractLaser guiding through an axially non-uniform collisional magnetoplasma channel formed by ionizing laser prepulse has been investigated. Self-defocusing of the ionizing prepulse leads to an axial non-uniform plasma channel. Due to the propagation of second laser beam through such preformed plasma channel, non-uniform heating of electrons takes place on account of non-uniform intensity distribution of laser beam. Non-uniform heating diffuses the electrons away from the axis and thereby enhances the plasma channel. Due to the competition between diffraction and refraction phenomenon through such an axial non-uniform collisional magnetoplasma channel, there is a periodic beam width variation with the distance of propagation. Second order ordinary differential equations for the beam width parameter of prepulse and the guided beam have been set up using the moment theory approach. Effect of axial non-uniformity, intensity of guided beam and magnetic field has been seen on the propagation of the second guided beam in the plasma channel.

Dissipative drift wave instability in a radially bounded nonuniform dusty magnetoplasma

Properties of the dissipative drift wave instability in a radially bounded nonuniform dusty magnetoplasma are investigated. By using the two-fluid model for the electrons and ions, we derive a nonlocal wave equation for the low-frequency collisional drift wave in the bounded system. The charged dust is assumed to be immobile on the time scale of the instability. The wave equation admits a dispersion relation, which exhibits the modification of the drift wave frequency and the dissipative drift wave instability growth rate due to radial boundaries. Possible application of our investigation to forthcoming nonuniform dusty magnetoplasma experiments is discussed.