Search results for "Nonlinear"
showing 10 items of 3684 documents
Nonlinear inverse bremsstrahlung and highly anisotropic electron distributions
1996
A procedure is proposed to deal with the approximate solution of the kinetic equation for the velocity distribution function of electrons in a fully ionized plasma in the presence of strong, high frequency radiation. The Legendre polynomial expansion is applied after the kinetic equation has been written in an oscillating frame, where some directions are appropriately scaled, with the aim of making approximately isotropic, on the average, distributions that are otherwise anisotropic. The equations are derived for the isotropic part of the electron distribution in the scaled frame and for the scaling factor. The procedure is meant to display its potential in cases where the electron distribu…
Non-adiabatic manipulation of slow-light solitons
2005
We provide an exact analytic description of decelerating, stopping and reaccelerating optical solitons in atomic media in the non-adiabatic regime. Dynamical control over slow-light pulses is realized via a nonlinear interplay between the solitons and the controlling field generated by an auxiliary laser. This leads to recovery of optical information. We discuss physically interesting features of our solution, which are in good agreement with recent experiments.
Ansatz independent solution of a soliton in a strong dispersion-management system
2001
We introduce a theoretical approach to the study of propagation in systems with periodic strongmanagement dispersion. Our approach does not assume any ansatz about the form of the solution nor does it make use of any average procedure. We find an explicit solution for the pulse evolution in the fast dynamics regime ~distances smaller than the dispersion period!. We also establish the equation of motion governing the slow dynamics of an arbitrary pulse and prove that the pulse evolution is nonlinear and Hamiltonian. We solve this equation and find that a nonlinear solitonlike solution occurs self-consistently in the form of an asymptotic stationary eigenfunction of the Hamiltonian.
COMPRESSION OF ENVELOPE SOLITONS IN NONLINEAR ELECTRICAL LINES
1989
Resume : La propagation des solitons enveloppe dans les lignes non lineaires de transmission electrique et de transmission Josephson est etudiee sous l'aspect theorique et en simulation numerique. Dans l'approximation des milieux continus et la limite des faibles amplitudes, les equations caracteristiques de ces lignes se ramenent a l'equation NLS . La solution "a deux solitons enveloppe" se propage parfaitement dans les lignes considerees avec des phenomenes de recurrence et de compression d'enveloppe. Ceci est observe egalement pour des profils d'excitation non solution de NLS, ce qui est d'un grand interet pour les applications pratiques.
Nonlinear SDE Excited by External Lévy White Noise Processes
2011
A numerical method for approximating the statistics of the solution of nonlinear stochastic systems excited by Gaussian and non-Gaussian external white noises is proposed. The differential equation governing the evolution in time of the characteristic function is resolved by the convolution quadrature method. This approach is especially suited for those problems in which the nonlinear drift term is not of polynomial form. In such cases the equation governing the evolution in time of the characteristic function is not a partial differential equation. Statistics are found by introducing an integral operator of Wiener-Hopf type, called the transformation operator, and applying the Lubich's con…
Static freezing transition at a finite temperature in a quasi-one-dimensional deuteron glass.
1996
The dipolar freezing process of a quasi-one-dimensional betaine deuteron glass was studied using linear and nonlinear dielectric spectroscopy. The linear response as measured for frequencies $5\mathrm{mHz}l\ensuremath{\nu}l200\mathrm{MHz}$ was analyzed using the recently invented $\ensuremath{\delta}$ plot, providing evidence for a static freezing transition near 30 K. Measurements of the ergodic to nonergodic transition as well as of the incipient divergence of the nonlinear susceptibility yield independent confirmation of this quasistatic freezing transition temperature. The critical exponent describing the nonlinear behavior is found to be $\ensuremath{\gamma}\phantom{\rule{0ex}{0ex}}=\p…
Incoherent Soliton Turbulence in Nonlocal Nonlinear Media
2011
The long-term behavior of a modulationally unstable nonintegrable system is known to be characterized by the soliton turbulence self-organization process: It is thermodynamically advantageous for the system to generate a large-scale coherent soliton in order to reach the (‘‘most disordered’’) equilibrium state. We show that this universal process of self-organization breaks down in the presence of a highly nonlocal nonlinear response. A wave turbulence approach based on a Vlasov-like kinetic equation reveals the existence of an incoherent soliton turbulence process: It is advantageous for the system to self-organize into a large-scale, spatially localized, incoherent soliton structure.
Influence of domain wall anisotropy on the current-induced hysteresis loop shift for quantification of the Dzyaloshinskii-Moriya interaction
2021
Using several material systems with various magnitudes of the interfacial Dzyaloshinskii-Moriya interaction (DMI), we elucidate a critical influence of domain wall (DW) anisotropy on the current-induced hysteresis loop shift scheme widely employed to determine the magnitude of the Dzyaloshinskii-Moriya effective field (${H}_{\mathrm{DMI}}$). Taking into account the DW anisotropy in the analysis of the hysteresis loop shift, which has not been included in the original model [Phys. Rev. B 93, 144409 (2016)], we show that it provides quantitative agreement of ${H}_{\mathrm{DMI}}$ with that determined from an asymmetric bubble expansion technique for small DMI material systems. For large DMI sy…
Nonlinear Evolution Equations, Quasi-Solitons and their Experimental Manifestation
1990
We review the typical experimental facts which characterize quasisolitons in one-dimensional real systems, in connection with their modeling by nonlinear partial differential equations.We consider these nonlinear waves or excitations in two different domains of the real world : the macroworld and the microworld. In the macroworld we examine typical one-dimensional devices : the electrical networks, the Josephson transmission lines and the optical fibers, where the localized waves or pulses can be simply and coherently created, easily observed and manipulated on a macroscopic scale. In the microworld, we consider the magnetic chains and polymers, where the indirect experimental signatures of…
Comment on "Highly nonlinear, sign-varying shift of hydrogen spectral lines in dense plasmas".
2004
The shift of hydrogen and hydrogenlike spectral lines in dense plasmas, calculated with the full computer simulation method, in nonquenching, classical path, dipole approximation for plasma-emitter interaction, is equal to zero. In the paper commented on, Escarguel et al., Phys. Rev. E 62, 2667 (2000) the electron concentrations ${N}_{e}$ and the corresponding temperature values T are shown to have been determined incorrectly.