Vortex bubble formation in pair plasmas.

It is shown that delocalized vortex solitons in relativistic pair plasmas with small temperature asymmetries can be unstable for intermediate intensities of the background electromagnetic field. Instability leads to the generation of ever-expanding cavitating bubbles in which the electromagnetic fields are zero. The existence of such electromagnetic bubbles is demonstrated by qualitative arguments based on a hydrodynamic analogy, and by numerical solutions of the appropriate nonlinear Schrödinger equation with a saturating nonlinearity.

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 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.

Plasma acceleration and cooling by strong laser field due to the action of radiation reaction force.

It is shown that for super intense laser pulses propagating in a hot plasma, the action of the radiation reaction force (appropriately incorporated into the equations of motion) causes strong bulk plasma motion with the kinetic energy raised even to relativistic values; the increase in bulk energy is accompanied by a corresponding cooling (intense cooling) of the plasma. The effects are demonstrated through explicit analytical calculations.

Radiation reaction and relativistic hydrodynamics.

By invoking the radiation reaction force, first perturbatively derived by Landau and Lifschitz, and later shown by Rohrlich to be exact for a single particle, we construct a set of fluid equations obeyed by a relativistic plasma interacting with the radiation field. After showing that this approach reproduces the known results for a locally Maxwellian plasma, we derive and display the basic dynamical equations for a general magnetized plasma in which the radiation reaction force augments the direct Lorentz force.

Angular momenta creation in relativistic electron-positron plasma.

Creation of angular momentum in a relativistic electron-positron plasma is explored. It is shown that a chain of angular momentum carrying vortices is a robust asymptotic state sustained by the generalized nonlinear Schrödinger equation characteristic to the system. The results may suggest a possible electromagnetic origin of angular momenta when it is applied to the MeV epoch of the early Universe.

Dynamics of self-trapped singular beams in an underdense plasma.

Dynamics of an intense short laser pulse with a phase singularity, propagating in an underdense cold plasma, is investigated. Such a pulse can propagate as a vortex soliton in a self-created channel. It is shown that vortices with the topological charge m=1,2 (and a corresponding angular momentum) are unstable against symmetry-breaking perturbations; the breakup of the original vortex leads to the formation of stable spatial solitons that steadily fly away tangentially from the initial ring of vortex distribution.

Self-trapping of strong electromagnetic beams in relativistic plasmas.

Interaction of an intense electromagnetic (em) beam with a relativistic electron-positron (e-p) plasma is investigated. It is shown that the thermal pressure brings about a fundamental change in the dynamics-localized, high amplitude, em field structures, not accessible to a cold (but relativistic) plasma, can now be formed under well-defined conditions. The possibilities of trapping em beams in self-guiding regimes to form stable two-dimensional solitonic structures in a pure e-p plasma are worked out.

Dynamics of localized and nonlocalized optical vortex solitons in cubic-quintic nonlinear media.

The nonlinear dynamics of laser beams carrying phase singularity in media with cubic-quintic nonlinearity changing from self-focusing to self-defocusing is examined. A novel kind of stable nonlocalized optical vortices appears in such media as well as localized vortex solitons. Linear stability analysis and numerical simulations show the stability of localized vortices only in the defocusing region.

Vortex solitons: mass, energy, and angular momentum bunching in relativistic electron-positron plasmas.

It is shown that the interaction of large amplitude electromagnetic waves with a hot electron-positron (e-p) plasma (a principal constituent of the universe in the MeV epoch) leads to a bunching of mass, energy, and angular momentum in stable, long-lived structures. Electromagnetism in the MeV epoch, then, could provide a possible route for seeding the observed large-scale structure of the universe.

Spatiotemporal dynamics of electromagnetic pulses in saturating nonlinear optical media with normal group velocity dispersion.

The nonlinear dynamics of ultrashort optical pulses in nonlinear saturating media with normal group velocity dispersion is examined. The studied saturating nonlinearity changes the sign at the peak intensity of the laser pulses. In the bulk media and the planar wave guides the temporal collapse of the pulse is arrested by its splitting in spatial domain leading to rings formation. The wave collapse in one dimensional geometry cannot be arrested; the field singularity develops for a finite propagation distance.