In this contribution the magnetic modelling and experimental validation of a superconducting degaussing system for maritime vessels is discussed. Degaussing coils compensate for the distortion in the earths’ magnetic field by the magnetized steel hull of a ship, thus rendering it ‘invisible’ for magnetic field sensors. Whereas typical power requirements with copper coils are of the order of...
No-insulation (NI) winding method has been widely used in the fabrication of superconducting coils due to its excellent thermal stability and mechanical stiffness. In the NI coil, there is a charging delay and heat loss due to leakage current and metal insulated (MI) winding method has been proposed to reduce the charging delay and the heat loss by the leakage current due to the increased...
This paper presents the results about analysis and experiment on the electrical and thermal characteristics of metal insulation (MI) REBCO racetrack coil wound with stainless steel (SS) tape under rotating magnetic field. The field windings of synchronous rotating machine can be occasionally operated under time-varying magnetic field due to the unsynchronized armature windings during...
Abstract:
High-temperature superconducting (HTS) magnet is a promising candidate for transportation systems and power systems, such as ultra-high field magnet, electrodynamic suspension (EDS) train, magnetic resonance imaging (MRI), due to its large current-carrying capacity and low power loss. The critical current of the HTS magnet depending on magnetic flux density is an essential...
We aim to develop a persistent-mode 1.3 GHz (30.5 T) LTS/HTS NMR magnet. For protecting the layer-wound REBCO innermost coil from quench, we have proposed the intra-Layer No-Insulation (LNI) method. This winding technique employs single-sided insulated copper sheets as inter-layer materials to provide the no-insulation state within each layer. For quench protection, the most influential...
REBCO tapes have good critical current characteristics under high magnetic fields. Their application to superconducting magnets generating above 25 T is under active study. However, performance inhomogeneity along their length can cause damaging hotspots. Adapted winding technologies are needed to mitigate this phenomenon. One of such winding techniques is the two-tape bundle co-winding...
The no-insulation (NI) winding technique provides high stability of HTS pancake coils and a high magnetic field NI HTS magnet was developed. On the other hand, the balance between the turn-to-turn contact resistance and the coil inductance is an important factor to characterize the thermal stability and charging delay of NI HTS coils. So, it is very important to accurately measure and evaluate...
Three racetrack type double-pancake coils were wound and assembled in a certain sequence to form a module. To improve the anisotropism between the straight sections and circular sections, the bobbin was designed and some clamping fixtures were added on both sides and on the straight sections. By investigating the viscosity and torque of rotor, the optimum range of temperature for impregnating...
In this study, the quench initiation and propagation characteristics of REBCO coil, which was electrically and thermally insulated by a vanadium III oxide (V2O3), were investigated under internal heater activation. When the quench occurs in REBCO coil, V2O3 insulator can enhance the thermal stability of REBCO coil due to its automatically and remarkably switched from high to low turn-to-turn...
The REBCO coil, which was electrically insulated using a metal-insulator transition (MIT) material between turn-to-turn contact layers, can achieve high stability in the transient operation as well as fast response of magnetic field in the normal operation due to its automatically switched electrical resistivity of MIT material according to the temperature changes. Among of MIT materials, A...
We propose a new active feedback control method to quickly charge no-insulation(NI) magnets, as well as sustaining thermal stability. The main feature of our suggested method is controlling ramping rate of the magnet to minimize consecutive Joule heating induced by the radial leakage current and resistive joint. The suggested method to be applicable for the iron core NI coils, dynamic...
No-insulation (NI) winding technique shows superior electrical and thermal performance for high temperature superconducting (HTS) coils compared with the insulation winding technique. However, the NI HTS winding technique is uncertain about the thermal contact resistance between winding turns because the HTS wire has various surface conditions such as roughness and oxidation. In this paper,...
