Experimental investigation of quench phenomena in YBCO thin films for SFCL applications

Superconducting Fault Current Limiters (SFCLs) are regarded as key components for modern power systems. The progress in the development of YBCO thin films opens new perspectives in the design of these devices. In this paper, the quenching phenomenon in YBCO thin films is investigated experimentally, in order to gain the proper technical know-how suitable for the design of resistive type SFCLs. In particular, the origin of the quenching, as well as the propagation dynamics within a YBCO tape, is investigated for different input current waveforms. The role of a parallel-connected protective resistance on the quench dynamic is also studied. © 2009 IEEE.

Modeling the carbon nanofiber addressed liquid crystal microlens array from experimentally observed optical phenomena

This paper presents a novel method of using experimentally observed optical phenomena to reverse-engineer a model of the carbon nanofiber-addressed liquid crystal microlens array (C-MLA) using Zemax. It presents the first images of the optical profile for the C-MLA along the optic axis. The first working optical models of the C-MLA have been developed by matching the simulation results to the experimental results. This approach bypasses the need to know the exact carbon nanofiber-liquid crystal interaction and can be easily adapted to other systems where the nature of an optical device is unknown. Results show that the C-MLA behaves like a simple lensing system at 0.060-0.276 V/μm. In this lensing mode the C-MLA is successfully modeled as a reflective convex lens array intersecting with a flat reflective plane. The C-MLA at these field strengths exhibits characteristics of mostly spherical or low order aspheric arrays, with some aspects of high power aspherics. It also exhibits properties associated with varying lens apertures and strengths, which concur with previously theorized models based on E-field patterns. This work uniquely provides evidence demonstrating an apparent "rippling" of the liquid crystal texture at low field strengths, which were successfully reproduced using rippled Gaussian-like lens profiles. © 2014 Published by Elsevier B.V.