Width-amplitude relation of Bernstein-Greene-Kruskal solitary waves

Inequality width-amplitude relations for three-dimensional Bernstein-Greene-Kruskal solitary waves are derived for magnetized plasmas. Criteria for neglecting effects of nonzero cyclotron radius are obtained. We emphasize that the form of the solitary potential is not tightly constrained, and the amplitude and widths of the potential are constrained by inequalities. The existence of a continuous range of allowed sizes and shapes for these waves makes them easily accessible. We propose that these solitary waves can be spontaneously generated in turbulence or thermal fluctuations. We expect that the high excitation probability of these waves should alter the bulk properties of the plasma medium such as electrical resistivity and thermal conductivity.Comment: 5 pages, 2 figure

Pseudospectral time-domain modeling of diffractive optical elements

We develop a pseudospectral multi-domain formulation for the accurate modeling of generic diffractive optical elements, here exemplified by off-plane waveguide holograms for the coupling between guided waves and freely propagating wavefronts. The individual elements entering the multi-domain formulation for the solution of the time-domain Maxwell equations is described, stressing the ability to accurately and efficiently handling very general geometric complexity and combinations of several materials. The efficacy of the overall scheme is illustrated by computing the time-domain solution of a plane waveguide problem and an off-plane waveguide coupler

Dynamics of nonstationary dipole vortices

The dynamics of tilted dipole vortices in the equivalent barotropic vorticity (or Hasegawa-Mima) equation is studied. A recent theory is compared with numerical simulations and found to describe the short time behavior of dipole vortices well. In the long time limit the dipoles are found to either disintegrate or relax toward a steady eastward propagating dipole vortex. This relaxation is a consequence of nonviscous enstrophy loss by the dipole vortex