Topic
Equilibrium mode distribution
About: Equilibrium mode distribution is a research topic. Over the lifetime, 928 publications have been published within this topic receiving 14939 citations.
Papers published on a yearly basis
Papers
More filters
01 Nov 2017
TL;DR: In this paper, a short-fiber-length mode scrambler that reproduces the equilibrium mode distribution of an A3e fiber was proposed. But it is not suitable for all-glass and optical fibers.
Abstract: We proposed a short-fiber-length mode scrambler that reproduces the equilibrium mode distribution of an A3e fiber. The mode scrambler is compact, mode-controllable and has low attenuation. It is effective for not only hard plastic-clad fiber but also all step-index fibers, such as all-glass and plastic optical fibers.
01 Jan 2008
TL;DR: In this article, a broad set of diagnostics is employed: the Mirnov coils show clearly the footprints of all electromagnetic modes with finite perturbation at the plasma edge and allow for a reliable mode number identification.
Abstract: Introduction and experimental features In many ICRF heated discharges (hydrogen minority heating) at ASDEX-Upgrade a variety of fast particle driven modes can be observed. In order to determine their nature and their possible impact on fast particle transport, a broad set of diagnostics is employed: the Mirnov coils show clearly the footprints of all electromagnetic modes with finite perturbation at the plasma edge and allow for a reliable mode number identification. The soft x-ray cameras deliver valuable information about the radial mode position. Finally, the energy and the pitch angle of expelled particles can be directly measured by the fast-ion-loss detector (FILD) diagnostic allowing to reconstruct possible resonance conditions and the mode amplitude evolution. During an IRCF power ramp, the toroidal Alfven Eigenmodes (TAE) with typical mode numbers n = 4...7 at typically 200 280 kHz appear first, indicating that they are the least damped modes under these experimental conditions. At higher heating power another electromagnetic mode at about 70 110kHz is observed, a so-called ’BAE’ [1, 2] or ’sierpes’ [3] mode. At ASDEX-Upgrade this mode seems to be closely connected with the appearance of a q = 1 surface and therefore with sawtooth oscillations (see Fig. 2). Its mode numbers are n = 4 with a dominant m = 4 component and it is located radially at ρ pol � 0.2 0.4 (SXR reconstruction with the MHD-IC code [4]). It has been demonstrated that this mode is non-Alfvenic since neither B-field ramps nor density changes influence the mode frequency. Furthermore, the appearance of the ’BAE’ mode enhances the FILD-losses induced by the TAE mode [3] suggesting a possible ’channelling’ effect between the ’BAE’ and the TAE. As in earlier publications [2], no clear scaling with only the ion sound speed or only the dia
TL;DR: A specialized coupler formed by two identical multimode graded-index slab fibers is described, which can be used to examine the tilt or the roughness of a surface through the reflected beam.
Abstract: A specialized coupler formed by two identical multimode graded-index slab fibers is described. This special coupler can be used to examine the tilt or the roughness of a surface through the reflected beam. It may also find applications as a mode filter, an alignment sensor, or a feed component of an optical monopulse tracking radar. Coupled-mode theory is generalized for this application. The coupling length for maximum power transfer of the higher-order modes from the excited to the coupled fiber, leaving as much power of the lowest mode as possible to continue in the excited fiber, is computed. The fields are computed at the output of the system for incident optical beams with different axial displacements and beams launched on axis with tilted wavefronts. This desired coupling length is shown to be substantially independent of characteristics of the incident light beam. To compute the fields propagated through the tapered section introduced to separate the slab fibers, the stairwise approximation is used, and mode matching is used to connect the fields at the junctions between the successive segments. An optimum taper to separate the coupled fibers, with minimal perturbation of the fields, is present at the right-hand end of the coupling section.
11 Jun 2006
TL;DR: In this article, a single mode optical fiber end coupled to an open cavity has been studied and the established fields inside the open cavity due to excited HE11 mode, transmission and reflection coefficients incorporating diffraction effects from the fiber end were formulated using the mode matching method.
Abstract: Fabry-Perot interferometer configuration consisting of a single mode optical fiber end coupled to an open cavity has been studied. The established fields inside the open cavity due to excited HE11 mode, transmission and reflection coefficients incorporating diffraction effects from the fiber end were formulated using the mode matching method. A semi-analytical algorithm that accounts for the vector nature of the fields was developed and evaluated. Numerical simulations were verified against experimental measurements.
18 Jul 2016
TL;DR: In this article, a large mode 3C optical fiber operating at 300kW of peak power and 25W of average power is shown to maintain truly single transverse mode functionality even after more than 1.5 years of continuous operation.
Abstract: Large mode 3C® optical fiber operating at 300kW of peak power and 25W of average power is shown to maintain truly single transverse mode functionality even after more than 1.5 years of continuous operation.