Spin-induced localized density excitations in quantum plasmas

In this paper the dominant effect of electron inertia on the dynamics of localized density excitations is studied in a quantum plasma in the presence of electron spin effects. Using the quantum magnetohydrodynamics (QMHD) model including electron tunneling and spin polarization phenomena, it is revealed that the quantum effects such as plasma paramagnetism and diamagnetism play inevitable role on soliton existence criteria in quantum plasmas. Furthermore, it is shown that the magnetosonic localized density-excitation stability depends strongly on the quantum system dimensionality. Two distinct region of soliton stability is shown to exist depending on the value of the electron effective mass, where, the soliton amplitude variation with respect to the external magnetic field strength is quite opposite in these regions. Current findings can be important in the study of dynamical nonlinear wave features in dense laboratory or inertial-confined plasmas.Comment: Paper accepted in journal IEEE Trans. Plasma Sc

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.Comment: To appear in IEEE Trans. Plasma Sci. arXiv admin note: text overlap with arXiv:1106.022

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.Comment: To appear in journal Physics of Plasma

Propagation of arbitrary amplitude nonlinear quantum ion-acoustic waves in electron-ion plasmas: Dimensionality effects

Propagation of arbitrary-amplitude ion-acoustic solitary (IASWs) as well as periodic waves (IAPWs) is investigated in a fully degenerate quantum electron-ion plasma consisting of isothermal- or adiabatic-ion species. It is shown that the system dimensionality and degrees of freedom play critical roles in matching criteria for propagation of such waves. Furthermore, it is revealed that for the case of adiabatic-ion unlike isothermal one, in some cases, there exists an upper fractional ion-temperature limit for the existence of IAPWs. It is also shown that, the variations of wave-amplitude with respect to the change in fractional ion-temperature is quite different for the cases of isothermal and adiabatic-ion plasmas.Comment: Accepted for publication in IEEE Trans. on Plasma Scienc