The concept of a ponderomotive force due to the intrinsic spin of electrons is developed. An expression containing both the classical as well as the spin-induced ponderomotive force is derived. The results are used to demonstrate that an electromagnetic pulse can induce a spin-polarized plasma. Furthermore, it is shown that for certain parameters, the nonlinear back-reaction on the electromagnetic pulse from the spin magnetization current can be larger than that from the classical free current. Suitable parameter values for a direct test of this effect are presented.PACS numbers: 52.35. Mw, The use of the spin properties of material constituents for e.g., carrying information is currently an important paradigm [1]. However, the spin properties of the material constituents also make its presence felt through collective effects. In particular, recent findings point to the possibility of observing quantum plasma effects [2] through the electron spin [3] in regimes otherwise thought to be classical [4]. Such results are due to the complex interplay between collective plasma effects and the system nonlinearities. In classical plasmas, nonlinear effects play an important, sometimes a crucial, role. For example, the density fluctuations induced by the ponderomotive force of an electromagnetic (EM) wave lead to an electrostatic wake field [5], as used in advanced particle accelerator schemes [6]. In other regimes, the back-reaction on the EM-wave due to the density fluctuations leads to phenomena such as soliton formation, self-focusing or wave collapse [7]. Such radiation pressure-like effects are widely used in high-intensity laser experiments [8], and generalizations to include certain types of quantum plasma effects have recently been made [9]. However, to our knowledge the possibility of spin induced contribution to the ponderomotive forces has not been explored.In the present work we will solve the full set of equations for the spin dynamics of charged particles in the presence of a weakly nonlinear EM wave pulse, propagating parallel to an external magnetic field, in order to find the contribution to the ponderomotive force. In the classical limit, we recover the well-known expression first derived by Karpman and Washimi [14]. The spin contribution to the ponderomotive force will in general act in opposite directions for spin-up and spin-down populations. As a consequence, an EM-pulse (due to, e.g., a laser or a microwave source) may induce a spin-polarized plasma. In particular, it is demonstrated that this mechanism can induce large spin-polarization for a laser source in the UV-regime. For this case it should be noted that the effect of the external magnetic field is negligible as the laser frequency is much higher than the cyclotron frequency, but our general expression applies also for lowfrequency (lf) waves in magnetized plasmas.When combined with the high-frequency (hf) oscillations, the classical lf density response generates a hf current that results in a cubical nonlinearity. This classical nonlinearit...

The influence of the intrinsic spin of electrons on the propagation of circularly polarized waves in a magnetized plasma is considered. New eigenmodes are identified, one of which propagates below the electron cyclotron frequency, one above the spin-precession frequency, and another close to the spin-precession frequency.\ The latter corresponds to the spin modes in ferromagnets under certain conditions. In the nonrelativistic motion of electrons, the spin effects become noticeable even when the external magnetic field $B_{0}$ is below the quantum critical\ magnetic field strength, i.e., $B_{0}<$ $B_{Q} =4.4138\times10^{9}\, \mathrm{T}$ and the electron density satisfies $n_{0} \gg n_{c}\simeq10^{32}$m$^{-3}$. The importance of electron spin (paramagnetic) resonance (ESR) for plasma diagnostics is discussed.Comment: 10 page

The one-dimensional quantum hydrodynamic model is considered in the limit of low phase velocity (compared to the Fermi thermal velocities) as well as the limit of low frequency (compared to the particle-neutral collision frequency) to study the amplitude modulation of dust-acoustic waves in a three-species quantum dusty plasma. Using the standard reductive perturbation technique, a nonlinear Schrödinger equation containing the quantum effects is derived. The quantum mechanical effects containing the quantum diffraction and quantum statistics on the modulational instability are studied both analytically and numerically. It is found that quantum effects are to suppress the instability.

Nonlinear propagation of quantum ion-acoustic waves (QIAWs) in a dense quantum plasma whose constituents are electrons, positrons, and positive ions is investigated using a quantum hydrodynamic model. The standard reductive perturbation technique is used to derive the Korteweg–de Vries–Burger (KdVB) equation for QIAWs. It is shown by numerical simulation that the KdVB equation has either oscillatory or monotonic shock wave solutions depending on the system parameters H proportional to quantum diffraction, μi the effect of ion kinematic viscosity, and μ the equilibrium electron to ion density ratio. The results may have relevance in dense astrophysical plasmas (such as neutron stars) as well as in intense laser solid density plasma experiments where the particle density is about 1025−1028m−3.

We study the effects of ion-dust collisions and ion kinematic viscosities on the linear ion-acoustic instability as well as the nonlinear propagation of small amplitude solitary waves and shocks (SWS) in a negative ion plasma with immobile charged dusts. The existence of two linear ion modes, namely the 'fast' and 'slow' waves is shown, and their properties are analyzed in the collisional negative ion plasma. Using the standard reductive perturbation technique, we derive a modified Korteweg-de Vries-Burger (KdVB) equation which describes the evolution of small amplitude SWS. The profiles of the latter are numerically examined with parameters relevant for laboratory and space plasmas where charged dusts may be positively or negatively charged. It is found that negative ion plasmas containing positively charged dusts support the propagation of SWS with negative potential. However, the perturbations with both positive and negative potentials may exist when dusts are negatively charged. The results may be useful for the excitation of SWS in laboratory negative ion plasmas as well as for observation in space plasmas where charged dusts may be positively or negatively charged.

The nonlinear propagation of electromagnetic (EM) electron-cyclotron waves (whistlers) along an external magnetic field, and their modulation by electrostatic small but finite amplitude ion-acoustic density perturbations are investigated in a uniform quantum plasma with intrinsic spin of electrons. The effects of the quantum force associated with the Bohm potential and the combined effects of the classical as well as the spin-induced ponderomotive forces (CPF and SPF, respectively) are taken into consideration. The latter modify the local plasma density in a self-consistent manner. The coupled modes of wave propagation is shown to be governed by a modified set of nonlinear Schrödinger-Boussinesq-like equations which admit exact solutions in form of stationary localized envelopes. Numerical simulation reveals the existence of large-scale density fluctuations that are self-consistently created by the localized whistlers in a strongly magnetized high density plasma. The conditions for the modulational instability (MI) and the value of its growth rate are obtained. Possible applications of our results, e.g., in strongly magnetized dense plasmas and in the next generation laser-solid density plasma interaction experiments are discussed.

In this paper we calculate the contribution to the ponderomotive force in a plasma from the electron spin using a recently developed model. The spin-fluid model used in the present paper contains spin-velocity correlations, in contrast to previous models used for the same purpose. Is its then found that previous terms for the spin-ponderomotive force are recovered, but also that additional terms appear. Furthermore, the results due to the spin-velocity correlations are confirmed using the spin-kinetic theory. The significance of our results is discussed.

The formation of dust ion-acoustic shocks (DIASs) in a four-component quantum plasma whose constituents are electrons, both positive and negative ions and immobile charged dust grains, is studied. The effects of both the dissipation due to kinematic viscosity and the dispersion caused by the charge separation as well as the quantum tunneling due to the Bohm potential are taken into account. The propagation of small but finite amplitude dust ion-acoustic waves (DIAWs) is governed by the Korteweg-de Vries-Burger (KdVB) equation which exhibits both oscillatory and monotonic shocks depending not only on the viscosity parameters η ± = µ ± ω p− /c 2 s (where µ ± are the coefficients of kinematic viscosity, ω p− is the plasma frequency for negative ions and c s is the ion-sound speed) but also on the quantum parameter H (the ratio of the electron plasmon to the electron Fermi energy) and the positive to negative ion density ratio β. Large amplitude stationary shocks are recovered for a Mach number (M ) exceeding its critical value (M c ). Unlike the small amplitude shocks, quite a smaller value of η + , η − , H and β may lead to the large amplitude monotonic shock strucutres. The results could be of importance in astrophysical and laser produced plasmas.