arXiv subjects
Publications and source records attributed to L. Stenflo.
The existence of two new low-frequency electrostatic modes in quantum dusty plasmas is pointed out. These modes can be useful to diagnose charged dust impurities in micro-electro-mechanical systems.
This paper is withdrawn because it is a duplicate of astro-ph/0601311
The collective production of electron-positron pairs by electrostatic waves in quantum plasmas is investigated. In particular, a semi-classical governing set of equation for a self-consistent treatment of pair creation by the Schwinger mechanism in a quantum plasma is derived.
The resonant interaction between three waves in a uniform magnetized plasma is considered. Using the somewhat inaccessible result of the general theory we deduce the explicit expressions for the coupling coefficients of a cold magnetized two-component plasma.
Using Hall-MHD theory, we focus on the resonant interaction between three kinetic Alfvén waves. We thus derive three coupled equations which govern this process. It turns out that these equations contain the same coupling coefficient, directly showing that they satisfy the Manley-Rowe relations. The coupling coefficient can be written in a comparatively very simple form, that has not been deduced before. The decay rate, when a pump kinetic Alfvén wave decays into two similar Alfvén waves, is therefore easily estimated for plasmas of astrophysical interest.
Nonlinear oscillations within a plasma slab are analyzed. Two types of solutions are found, depending on the initial value of the electron density. The first represents regular oscillations within the plasma slab, while the second gives rise to explosive growth at the slab centre or at the edges. The results are discussed.
We present a stability analysis of a modified nonlinear Schroedinger equation describing the propagation of ultra-short pulses in negative refractive index media. Moreover, using methods of quantum statistics, we derive a kinetic equation for the pulses, making it possible to analyze and describe partial coherence in metamaterials. It is shown that a novel short pulse soliton, which is found analytically, can propagate in the medium.
A dispersion relation for electromagnetic wave propagation in a strongly magnetized cold plasma is deduced, taking photon-photon scattering into account. It is shown that the combined plasma and quantum electrodynamic effect is important for understanding the mode-structures in magnetar and pulsar atmospheres. The implications of our results are discussed.
A new nonlinear electromagnetic wave mode in a magnetized dusty plasma is predicted. Its existence depends on the interaction of an intense circularly polarized electromagnetic wave with a dusty plasma, where quantum electrodynamical photon-photon scattering is taken into account. Specifically, we consider a dusty electron-positron-ion plasma, and show that the propagation of the new mode is admitted. It could be of significance for the physics of supernova remnants and in neutron star formation.
The stability of colliding Bose-Einstein condensates is investigated. A set of coupled Gross-Pitaevskii equations is thus considered, and analyzed via a perturbative approach. No assumption is made on the signs (or magnitudes) of the relevant parameters like the scattering lengths and the coupling coefficients. The formalism is therefore valid for asymmetric as well as symmetric coupled condensate wave states. A new set of explicit criteria is derived and analyzed. An extended instability region, in addition to an enhanced instability growth rate is predicted for unstable two component bosons, as compared to the individual (uncoupled) state.
A new nonlinear electromagnetic wave mode in a magnetized plasma is predicted. Its existence depends on the interaction of an intense circularly polarized electromagnetic wave with a plasma, where quantum electrodynamical photon--photon scattering is taken into account. This scattering gives rise to a new coupling between the matter and the radiation. Specifically, we consider an electron--positron plasma, and show that the propagation of the new mode is admitted. It could be of significance in pulsar magnetospheres, and result in energy transport between the pulsar poles.
We present exact electromagnetic solitary pulses that can be experimentally obtained within nonlinear left-handed metamaterials. The effect of pulse decoherence on the modulation instability of partially incoherent electromagnetic waves is also investigated. The results may contribute to a better understanding of nonlinear electromagnetic pulse propagation in media with negative index of refraction.
It is well-known that a charged particle moving with constant velocity in vacuum does not radiate. In a medium the situation can be different. If the so called Cherenkov condition is satisfied, i.e. the particle velocity exceeds the phase speed in the medium, the particle will radiate. We show that a charge moving with a constant velocity in a gas of photons emits Cherenkov radiation, even in the gamma-ray regime, due to nonlinear quantum electrodynamic effects. Our result is evaluated with respect to the radiation background in the early universe, and it is argued that the effect can be significant.
The nonlinear interaction, due to quantum electrodynamical (QED) effects, between photons is investigated using a wave-kinetic description. Starting from a coherent wave description, we use the Wigner transform technique to obtain a set of wave-kinetic equations, the so called Wigner-Moyal equations. These equations are coupled to a background radiation fluid, whose dynamics is determined by an acoustic wave equation. In the slowly varying acoustic limit, we analyse the resulting system of kinetic equations, and show that they describe instabilities, as well as Landau-like damping. The instabilities may lead to break-up and focusing of ultra-high intensity multi-beam systems, which in conjunction with the damping may result in stationary strong field structures. The results could be of relevance for the next generation of laser-plasma systems.
The nonlinear interaction, due to quantum electrodynamical (QED) effects, between two electromagnetic pulses and a radiation gas is investigated. It is found that the governing equations admit both modulational and filamentational instabilities. The instability growth rates are derived, and the results are discussed.
In quantum electrodynamics, photon--photon scattering can be the result of the exchange of virtual electron--positron pairs. Effectively, this gives rise to self-interaction terms in Maxwell's equations, similar to the nonlinearities due to polarization in nonlinear optics. These self-interaction terms vanish in the limit of parallel propagating waves. However if the modes generated in bounded regions are used, there will be a non-zero total effect. We show that stationary two-dimensional light bullets can form in guiding structures, due to the balancing effect of quantum electrodynamical vacuum nonlinearities on dispersion and diffraction. These light bullets are unstable and exhibit the possibility of self-focusing collapse. The consequences of our results are also discussed.