213 research outputs found
Localized whistlers in magnetized spin quantum plasmas
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
Schr\"{o}dinger-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.Comment: 9 pages, 4 figures; To appear in Physical Review E (2010
Asymmetry-Driven Structure Formation in Pair Plasmas
The nonlinear propagation of electromagnetic waves in pair plasmas, in which
the electrostatic potential plays a very important but subdominant role of a
"binding glue" is investigated. Several mechanisms for structure formation are
investigated, in particular, the "asymmetry" in the initial temperatures of the
constituent species. It is shown that the temperature asymmetry leads to a
(localizing) nonlinearity that is new and qualitatively different from the ones
originating in ambient mass or density difference. The temperature asymmetry
driven focusing-defocusing nonlinearity supports stable localized wave
structures in 1-3 dimensions, which, for certain parameters, may have flat-top
shapes.Comment: 23 pages, 6 figures, introduction revised, edited typos, accepted for
publication in Phys. Rev.
- …