We describe a class of diffractive optical elements intended for use in holographic optical trapping systems that project ring-like optical traps. Unlike optical vortex traps, which carry orbital angular momentum, these ring-like traps implement a force-free one-dimensional potential energy well for micrometer scale objects. Also unlike most optical vortices or ring-like Bessel beams, these rin...

Stability of onand off-site vortex solitons with unit charge in a photorefractive optical lattice is analysed. It is shown that both types of vortex solitons are linearly unstable in the highand low-intensity regimes. In the highintensity regime, the vortex appears as a familiar ring vortex, and it suffers oscillatory instabilities. In the low-intensity regime, the vortex suffers both oscillato...

We construct a smooth family of Hamiltonian systems, together with a family of group symmetries and momentum maps, for the dynamics of point vortices on surfaces parametrized by the curvature of the surface. Equivariant bifurcations in this family are characterized, whence the stability of the Thomson heptagon is deduced without recourse to the Birkhoff normal form, which has hitherto been a ne...

R. N. Bisset,1,* Wenlong Wang,2 C. Ticknor,3 R. Carretero-González,4 D. J. Frantzeskakis,5 L. A. Collins,3 and P. G. Kevrekidis1,6 1Center for Nonlinear Studies and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA 2Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA 3Theoretical Division, Los Alamos National Laboratory, Lo...

Graduate Aeronautical Laboratories, Californ ia Institute ol Technology, Pasadena. CA 91125 The interaction of turbulent vortex rings that approach a clean water surface under various angles is experimentally investigated. The temporal evolution of the vortex rings with an initial Reynolds number of Re0 = 7500 is characterized by the Laminar/ turbulent transition and asymptotic relaminarization...

A joint experimental and computational methodology is developed and applied to investigate a vortex ring impinging normally on a wall. The method uses digital particle image velocimetry to make planar flow measurements, which are then used to initialize a second-order finite difference calculation. The experiment and the simulation are compared at later times and agree extremely well. The ring ...

Saturn rings are most beautiful and dynamic places in the solar system, consisting of ice particles in a constant battle between the gravitational forces of Saturn and its many moons. Fan, spiral, propellers, moonlets and streamer-channels observed by CASSINI in the F-ring have been attributed to encounters by Prometheus on the F ring, with investigations of optical thickness revealing large po...

The nonlinear Schrödinger equation is used to analyze the superfluid flow around an ion and to elucidate the vortex nucleation process. Asymptotic expansion for the flow is used to find the critical velocity of the ion for vortex production. 3D numerical calculations demonstrate, that if the axisymmetry of the flow is broken by introducing a solid boundary several healing length from the sphere...