Search

Most HTS (high-temperature superconductor) coils will quench due to defects in the winding. Some of these defects come from tape manufacturing, but more commonly are generated in the process of making a coil, especially for the YBCO racetrack coils that use epoxy resin to solidify the winding. In order to find out defects, chemical solutions are used to dissolve epoxy resin of three damaged YBCO racetrack coils. YBCO tapes reclaimed from these coils are scanned by MCorder, a continuous critical current measurement device that can tell amplitude of defects and distribution of defects in a high speed and high resolution. The scan result shows severe defects everywhere in the winding. However, during the solidification process, outer turns are more vulnerable to the defects than the inner turns. We believe that the delamination of YBCO tape caused by contraction of the epoxy resin contributes to the defects. [ABSTRACT FROM PUBLISHER]

Since there is no iron core and the energy is only coupled through the primary and secondary windings, air-core transformers have advantages of no iron loss, no magnetic saturation, and compact in size, which make them attractive to be studied for practical applications. Due to its high current density and low loss, high temperature superconductor (HTS) brings additional advantages for this type of transformer. The HTS wires are highly magnetic field dependent and their characteristics are required for the HTS implementation and the design of the air-core transformers. As a result, magnetic field distribution of the HTS windings is researched, and its influence on the HTS critical currents, ac loss, and the transforming efficiency of the HTS air-core are analyzed. [ABSTRACT FROM AUTHOR]