Magnetized current filaments as a source of circularly polarized light

We show that the Weibel or current filamentation instability can lead to the emission of circularly polarized radiation. Using particle-in-cell simulations and a radiation post-processing numerical algorithm, we demonstrate that the level of circular polarization increases with the initial plasma magnetization, saturating at ${\sim }13\,\%$ when the magnetization, given by the ratio of magnetic energy density to the electron kinetic energy density, is larger than 0.05. Furthermore, we show that this effect requires an ion–electron mass ratio greater than unity. These findings, which could also be tested in currently available laboratory conditions, show that the recent observation of circular polarization in gamma-ray burst afterglows could be attributed to the presence of magnetized current filaments driven by the Weibel or current filamentation instability.

In-Fiber Structured Particles and Filament Arrays from the Perspective of Fluid Instabilities

In-fiber structured particles and filament array have been recently emerging, providing unique advantages of feasible fabrication, diverse structures and sophisticated functionalities. This review will focus on the progress of this topic mainly from the perspective of fluid instabilities. By suppressing the capillary instability, the uniform layered structures down to nanometers are attained with the suitable materials selection. On the other hand, by utilizing capillary instability via post-drawing thermal treatment, the unprecedent structured particles can be designed with multimaterials for multifunctional fiber devices. Moreover, an interesting filamentation instability of a stretching viscous sheet has been identified during thermal drawing, resulting in an array of filaments. This review may inspire more future work to produce versatile devices for fiber electronics, either at a single fiber level or in large-scale fabrics and textiles, simply by manipulating and controlling fluid instabilities.