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M. Akbari-Moghanjoughi

Publications and source records attributed to M. Akbari-Moghanjoughi.

At least 37 records · Page 2Linked to original sources
arXiv2017

Pseudoquatum Features of Parametrically Driven Classical Fluids

Recent experiments on walking droplets suggest an underlying connection between fluid dynamics and the quantum mechanics. Such experiments may be used to support the de Broglie-Bohm pilot-wave theory. In this paper we show that many quantum-like features of hydrodynamic excitations can be explained in the framework of the parametrically driven nonlinear Schrödinger equation (DNLSE). It is shown that the nonlinear Schrödinger equation (NLSE) describes the pseudoquantum features of a given pseudoparticle in the Sagdeev pseudopotential just as the ordinary linear Schrödinger equation (LSE) describes the quantum nature of real particles. The NLSE is shown to reduce to nonlinear Hamilton-Jacobi equation (NHJE) for the phase function of the complex wavefunction. The origin of the wave-particle dual-character in both LSE and NLSE is explained and basic similarities between the two models is highlighted. It is shown that many more pseudoquantum effects (yet to be explored) such as pseudoentanglement, self-interference effect and quantization of pseudoparticle energy are inherent features of classical fluids. Current investigation suggests that emergence of the quantum nature of fluids is independent from dynamics of the bouncing droplets or their interactions with the surface waves instantaneously created by them. In contrast to previous suggestions, it is remarked that intrinsically nonlinear collective excitations of a fluid can drive any particle even a pseudoparticle to behave quantum mechanically. These collective interactions in hydrodynamic model confirm the important nonlocal character (which is a key aspect of the de Broglie-Bohm pilot-wave theory) of all the pseudoquantum phenomena. The recent hydrodynamic quantum analog experiments and extensive new theoretical models may hopefully enable physicists to unlock the decade long hidden mystery of the quantum weirdness.

nlin.PS↗
arXiv2012

Comment on "On Novel attractive forces between ions in quantum plasmas -- failure of linearized quantum hydrodynamics"

In a recent paper Bonitz, Pehlke and Schoof [1], hereafter referred to as BPS, have raised some points against the newly found Shukla-Eliasson attractive potential [2,3], hereafter refererred to as SEAP, around a stationary test charge in a quantum plasma [2,3]. Our objective here is to discuss the inappropriateness of BPS reasoning concerning the applicability of the linearized quantum hydrodynamic theory, as well as to point out the shortcomings in BSP's arguments and to suggest for rescuing the BSP's density functional theory and simulations which have failed to produce results that correctly match with that of Shukla and Eliasson [2,3].

physics.plasm-ph↗
arXiv2012

Shukla-Eliasson Attractive Force: Revisited

By investigation of the dielectric response of a Fermi-Dirac plasma in the linear limit and evaluation of the electrostatic potential around the positive stationary test charge, we find that the Shukla-Eliasson attractive force is present for the plasma density range expected in the interiors of large planets for a wide range of plasma atomic-number. This research which is based on the generalized electron Fermi-momentum further confirms the existence of the newly discovered Lennard-Jones-like attractive potential and its inevitable role in plasma crystallization in the cores of planets. Moreover, it is observed that the characteristics of the attractive potential is strongly sensitive to the variation of the plasma density and composition. Current research can also have applications in the study of strong laser-matter interactions and innertially confined plasmas.

astro-ph.EP↗
arXiv2012

Phase Transition in Relativistically Degenerate Quantum Plasmas

In this paper we present the generalized phase separation diagram for quantum plasmas revealing the fundamental mechanism called the spontaneous core collapse (SCC) for a white dwarf star core-density based on the extended Shukla-Eliasson force for relativistically degenerate matter taking into account the most important electron interaction features such as Fermi-Dirac statistical pressure, Coulomb, exchange-correlation and quantum tunneling effects. A critical core mass-density value is reported for white dwarf stars beyond which the SCC mechanism will be inevitable. It is revealed that the SCC critical core-density value is slightly affected by the ion charge state, $Z$ (the core composition). Such fundamental effect which is mainly caused by the electron quantum diffraction effect can progressively lead the white dwarf star with a mass beyond the Chandrasekhar limit through SCC, core fusion and the ultimate supernova stages.

physics.plasm-ph↗
arXiv2012

Theory for large amplitude electrostatic ion shocks in quantum plasmas

We present a generalized nonlinear theory for large amplitude electrostatic (ES) ion shocks in collisional quantum plasmas composed of mildly coupled degenerate electron fluids of arbitrary degeneracy and non-degenerate strongly correlated ion fluids with arbitrary atomic number. For our purposes, we use the inertialess electron momentum equation including the electrostatic, pressure gradient and relevant quantum forces, as well as a generalized viscoelastic momentum (GVEM) equation for strongly correlated non-degenerate ions. The ion continuity equation, in the quasi-neutral approximation, then closes our nonlinear system of equations. When the electric field is eliminated from the GVEM equation by using the inertialess electron momentum equation, we then obtain a generalized GVEM and the ion continuity equations exhibiting nonlinear couplings between the ion number density and the ion fluid velocity. The pair of nonlinear equations is numerically solved to study the dynamics of arbitrary large amplitudes planar and non-planar ES shocks arising from the balance between harmonic generation nonlinearities and the ion fluid viscosity for a wide range of the plasma mass-density and the ion atomic-number that are relevant for the cores of giant planets (viz. the Jupiter) and compact stars (viz. white dwarfs). Our numerical results reveal that the ES shock density profiles strongly depend on the plasma number density and composition (the atomic-number) parameters. Furthermore, density perturbations propagate with Mach numbers which significantly dependent on the studied plasma fractional parameters. It is concluded that the dynamics of the ES shocks in the super-dense degenerate plasma is quite different in the core of a white dwarf star from that in the lower density crust region.

astro-ph.HE↗
arXiv2012

Field-Induced Degeneracy Regimes in Quantum Plasmas

It is shown that in degenerate magnetized Fermi-Dirac plasma where the electron-orbital are quantized distinct quantum hydrodynamic (QHD) limits exist in which the nonlinear density waves behave differently. The Coulomb interaction among degenerate electrons affect the electrostatic nonlinear wave dynamics more significant in the ground-state Landau quantization or the so-called quantum-limit ($l=0$) rather than in the classical-limit ($l=\infty$). It is also remarked that the effective electron quantum potential unlike the number-density and degeneracy pressure is independent of the applied magnetic field in the classical-limit plasma, while, it depends strongly on the field strength in the quantum-limit. Current findings are equally important in the study of wave dynamics in arbitrarily-high magnetized astrophysical and laboratory dense plasmas.

physics.plasm-ph↗
arXiv2012

Orbital Ferromagnetism and the Chandrasekhar Mass-Limit

In this paper, using both quantum magnetohydrodynamic (MHD) and magnetohydrostatic (MHS) models of a relativistically degenerate magnetic compact star, the fundamental role of Landau orbital ferromagnetism (LOFER) on the magneto-gravitational stability of such star is revealed. It is shown that the previously suggested magnetic equation of state for LOFER with some generalization of form $B=βρ^{2s/3}$ only within the range $0\leq s\leq 1$ and $0\leq β< \sqrt{2π}$ leads to magneto-gravitational stability with distinct critical value $β_{cr}=\sqrt{2π}$ governing the magnetohydrostatic stability of the compact star. Furthermore, the value of the parameters $s$ and $β$ is shown to fundamentally control both the quantum and Chandrasekhar gravitational collapse mechanisms and the previously discovered mass-limit on white dwarfs. Current findings can help to understand the origin of magnetism and its inevitable role on the stability of the relativistically degenerate super-dense magnetized matter encountered in many white-dwarfs and neutron stars.

astro-ph.SR↗
arXiv2012

Characteristics of Quantum Magnetosonic-Wave Dispersion

Using the quantum magnetohydrodynamics (QMHD) model, linear dispersion of magnetosonic waves are studied in a quasineutral quantum electron-ion plasma in two distinct regimes of nonrelativistic and relativistic degeneracies considering also the plasma composition effect. It is shown that the paramagnetic spin effects of the degenerated electrons plays a key role in dynamics of magnetosonic waves. The linear wave-speed is found to have minimum value at some degeneracy parameter in such plasmas. This is due to delicate interplay between relativistic degeneracy and the Pauli spin-magnetization. It is also revealed that the plasma composition has significant effect on the linear dispersion in the relativistic degeneracy limit contrary to that of nonrelativistic case and Zeeman energy has significant effect in nonrelativistic degeneracy regime unlike that of relativistic one in the linear perturbation-limit. Current findings can have important applications in both inertial plasma confinement and astrophysical degenerate plasmas.

physics.plasm-ph↗
arXiv2012

Exact Nonlinear Excitations in Double-Degenerate Plasmas

In this work we use the conventional hydrodynamics (HD) formalism and incorporate the Chew-Goldberger-Low (CGL) double-adiabatic theory to evaluate the nonlinear electrostatic ion excitations in double-degenerate (electron spin-orbit degenerate) magnetized quantum plasmas. Based on the Sagdeev pseudopotential method an exact general pseudopotential is calculated which leads to the allowed Mach-number range criteria for such localized density structures in an anisotropic magnetized plasma. We employ the criteria on the Mach-number range for diverse magnetized quantums plasma with different equations of state (EoS). It is remarked that various plasma fractional parameters such as the system dimensionality, ion-temperature, relativistic-degeneracy, Zeeman-energy, and plasma composition are involved in the stability of an obliquely propagating nonlinear ion-acoustic wave in a double-degenerate quantum plasma. Current study is most appropriate for nonlinear wave analysis in the dense astrophysical magnetized plasma environments such as white-dwarfs and neutron-star crusts where the strong magnetic fields can be present.

physics.flu-dyn↗
arXiv2012

Heavy-Fermion Instability in Double-Degenerate Plasmas

In this work we study the propagations of normal frequency modes for quantum hydrodynamic (QHD) waves in the linear limit and introduce a new kind of instability in a double-degenerate plasma. Three different regimes, namely, low, intermediate and high magnetic field strengths are considered which span the applicability of the work to a wide variety of environments. Distinct behavior is observed for different regimes, for instance, in the laboratory-scale field regime no frequency-mode instability occurs unlike those of intermediate and high magnetic-field strength regimes. It is also found that the instability of this kind is due to the heavy-fermions which appear below a critical effective-mass parameter ($μ_{cr}=\sqrt{3}$) and that the responses of the two (lower and upper frequency) modes to fractional effective-mass change in different effective-mass parameter ranges (below and above the critical value) are quite opposite to each other. It is shown that, the heavy-fermion instability due to extremely high magnetic field such as that encountered for a neutron-star crust can lead to confinement of stable propagations in both lower and upper frequency modes to the magnetic poles. Current study can have important implications for linear wave dynamics in both laboratory and astrophysical environments possessing high magnetic fields.

physics.plasm-ph↗
arXiv2012

Comment on the article "Solitary waves and double layers in an ultra-relativistic degenerate dusty electron-positron-ion plasma" [Phys. Plasmas \textbf{19}, 033705 (2012)]

More recently, N. Roy et al. [Phys. Plasmas \textbf{19}, 033705 (2012)] have investigated the occurrence of nonlinear solitary and double-layers in an ultrarelativistic dusty electron-positron-ion degenerate plasma using a Sagdeev potential method. They have considered a full parametric examination on Mach-number criteria for existence of such nonlinear excitations using the specific degeneracy limits of Chandrasekhar equation of state (EoS) for Fermi-Dirac plasmas. In this comment we point-out a misleading extension of polytropic EoS to study the Fermi-Dirac relativistically degenerate plasmas.

astro-ph.SR↗
arXiv2012

Nonlinear Excitations in Strongly-Coupled Fermi-Dirac Plasmas

In this paper we use the conventional quantum hydrodynamics (QHD) model in combination with the Sagdeev pseudopotential method to explore the effects of Thomas-Fermi nonuniform electron distribution, Coulomb interactions, electron exchange and ion correlation on the large-amplitude nonlinear soliton dynamics in Fermi-Dirac plasmas. It is found that in the presence of strong interactions significant differences in nonlinear wave dynamics of Fermi-Dirac plasmas in the two distinct regimes of nonrelativistic and relativistic degeneracies exist. Furthermore, it is remarked that first-order corrections due to such interactions (which are proportional to the fine-structure constant) are significant on soliton dynamics in nonrelativistic plasma degeneracy regime rather than relativistic one. In the relativistic degeneracy regime, however, these effects become less important and the electron quantum-tunneling and Pauli-exclusion dominate the nonlinear wave dynamics. Hence, application of non-interacting Fermi-Dirac QHD model to study the nonlinear wave dynamics in quantum plasmas such as compact stars is most appropriate for the relativistic degeneracy regime.

astro-ph.SR↗
arXiv2012

Coulomb Stability-Shatter: Consequences for Compact-Stars

In this research the transverse hydrostatic stability of a gravitating Fermi-Dirac plasma under a quantizing field is explored. It is revealed that such plasma is magnetically unstable due to the Landau electron spin-orbit quantization in all magnetic levels which might explain the gravitational compactification in the case of magnetic compact-stars. It is also revealed that the Coulomb interaction plays a fundamental role in the magnetic instability when a critical field is reached for a given plasma composition. It is remarked that, the Coulomb interaction, on specific condition depending on the field-strength and plasma composition, can suddenly destroy the transverse stability of the relativistically degenerate Fermi-Dirac plasma. The consequences of such instability on mass-limit of magnetic compact-stars and the neutron star crust with possible relation to gamma-ray bursts is numerically examined.

astro-ph.SR↗
arXiv2011

Orbital Ferromagnetism and Quantum Collapse in Stellar Plasmas

The possibility of quantum collapse and characteristics of nonlinear localized excitations is examined in dense stars with Landau orbital ferromagnetism in the framework of conventional quantum magnetohydrodynamics (QMHD) model including Bohm force and spin-orbit polarization effects. Employing the concepts of effective potential and Sagdeev pseudopotential, it is confirmed that the quantum collapse and Landau orbital ferromagnetism concepts are consistent with the magnetic field and mass-density range present in some white dwarf stars. Furthermore, the value of ferromagnetic-field found in this work is about the same order of magnitude as the values calculated earlier. It is revealed that the magnetosonic nonlinear propagations can behave much differently in the two distinct non-relativistic and relativistic degeneracy regimes in a ferromagnetic dense astrophysical object. Current findings should help to understand the origin of the most important mechanisms such as gravitational collapse and the high magnetic field present in many compact stars.

astro-ph.SR↗
arXiv2011

Universal characteristics of ion-acoustic wave dynamics in magnetized plasmas with emphasis on Tsallis distribution

Using the extended Poincaré-Lighthill-Kuo (PLK) reductive perturbation method, which incorporates the phase-shift variations, it is shown that common features on propagation and head-on collisions of ion-acoustic waves exist for a magnetized plasmas of different inertial-less particle distributions. For instance it is remarked that, the soliton amplitude is always independent of magnetic field strength while strictly depends on its angle regarding the propagation direction. Both types of solitons (compressive or rarefactive) are shown to exist which are defined through the critical angle $γ=π/2$ or other critical values depending on plasma fractional parameters. These critical plasma parameter values also define the sign of head-on collision phase shift. Furthermore, it is proved that for a given set of plasma parameters there is always a relative angle of propagation regarding to that of the magnetic-field for which the soliton width is maximum. Current findings applies to a wide range of magnetized plasmas including those containing background dust ingredients or two-temperature inertial-less particles and may be used to study laboratory or astrophysical magnetoplasmas.

astro-ph.HE↗
arXiv2011

Higher-order nonlinear electron-acoustic solitary excitations in partially degenerate quantum electron-ion plasmas

Propagation of dressed solitary excitations are studied in a partially degenerate quantum plasma in the framework of quantum-hydrodynamics (QHD) model using multiple scales technique. The evolution equation together with a linear inhomogeneous differential equation is solved using Kodama-Taniuti renormalizing technique. It is shown that the type of solitary excitations (bright or dark) is defined by two critical plasma parameter values.

astro-ph.SR↗