In this paper, we propose an improved wire structure that easily causes current bypass when the V2O3 material is applied turn-to-turn in 2G HTS no-insulation coils. A characteristic of the V2O3 material is that when a quench causes the coil temperature to rise the turn-to-turn resistance is lowered and current is bypassed. However, due to the high material resistance of the original 2G HTS...
A no-insulation (NI) winding technique has been utilized in high-temperature superconducting (HTS) coils owing to enhanced thermal and electrical stabilities as well as high mechanical strength. However, the charge-discharge rate of the NI coil is considerably slower than that of completely insulated coils. Although metal-insulation (MI) and partial-insulation (PI) winding techniques have been...
Recently, there have been sustained efforts to develop novel epoxy composites including various fillers for improving the physical properties of the epoxy-impregnated superconducting coil. Among the various filler materials, carbon nanotubes (CNTs) have emerged as one of the promising candidates because of the high thermal conductivity as well as the superior mechanical strength. However,...
Recently, no insulation (NI) and partial insulation (PI) techniques are proposed and studied for the compact and stable high temperature superconducting (HTS) coils. We have been studied the methods to improve the self-protection ability of HTS coils by removing the turn-to-turn insulation and inserting a metal tape instead of an electrical insulation. The operating current in the NI and/or PI...
If a quench occurs in an HTS magnet, it is almost impossible to protect the magnet from being burned. So far, it was usual to wind a magnet with insulated wires. However the insulated magnets are easily burned by a quench. To solve this problem no-insulation winding technique is developed recently. A no-insulation magnet shows very stable performance. However this magnet shows very poor...
A glass fiber reinforced plastic (GFRP) has been widely used for electric insulation in a high temperature superconducting (HTS) winding. Since thermal conductivity in the GFRP is low, the GFRP makes thermal flow from the superconducting winding to a cold head of a refrigerator worse. When a high thermal conduction plastic is used instead of the GFRP, the cooling performance in the winding...
AC loss and eddy current loss are inevitable in AC HTS (High Temperature Superconductor) magnets and even in DC HTS magnets under varying magnetic field or current. To secure thermal stability, especially in the conduction cooling, reduction of contact thermal resistances (CTR) is one of the crucial factors. To avoid the delamination problem, epoxy is not usually used between turns of ReBCO...
CCT technology promises, by its intrinsic stress-management, to lower coil stresses in high-field accelerator magnets. This is especially relevant for Nb3Sn magnets, which may be subject to irreversible degradation if the coil stresses exceed critical values. The internal structure of CCT coils, however, dilutes the engineering current density. For an efficient design, the internal structure,...
The electromagnetic-thermal model for Cable-in-Conduit Conductors JackPot-ACDC and THEA (Thermal, Hydraulic and Electric Analysis of superconducting cables) are combined for prediction of the stability of ITER Central Solenoid conductors. The combination of both models allows to predict the effect of any type of magnetic field perturbation in time relevant for the magnet coils during the...
REBCO coated conductor has architecture of metal substrate/ buffer layers / REBCO layer/ metal over-layers. Multilayer thin films are deposited on metal substrate by various deposition or coating technique. From this structures, films delamination and interfacial failure in coil applications are caused by thermal mismatch strains and potentially high Lorentz forces. We have proposed advanced...
We present a Finite Element Method (FEM) analysis of stability, heating and quench propagation in a conduction cooled race track coil at 20 K. The coil was assumed to be wound using YBCO coated conductor tape either non-insulated or insulated by a kapton tape. An anisotropic continuum model of the winding for thermal propagation, with input parameters taken from experiments, was developed and...
The development of the Toroidal field coils of the upcoming European DEMO reactor is under the coordination of the EUROfusion Consortium. The Swiss Plasma Center (SPC) and ENEA-Fusion produced two new cable concepts, RW1 (react and wind) and WR1 (wind and react) with rectangular cross section, inspired by existing concepts of Nb3Sn Cable-in-Conduit Conductors (CiCCs). The prototypes have been...
The JackPot-ACDC model, an electromagnetic-thermal model for Cable-in-Conduit Conductors and THEA, a thermo-hydraulic model for superconductors can be combined to reproduce and predict the behavior of a conductor under any current and magnetic field variations. JackPot+THEA is used to model the most demanding turns of the CSU2 module quadra-pancake of the ITER Central Solenoid. The chosen...
Many researchers have a great interest in applying no-insulation (NI) REBCO pancake coils to high field magnets used for NMR, MRI, and accelerator applications, because NI REBCO pancake coils have a high thermal stability. When a local normal hot spot appears in an NI REBCO pancake coil, the operating current can flow from the turn to the adjacent turns so as to avoid the hot spot. In other...
As a turn-to-turn insulation material on second generation high-temperature superconducting (2G HTS) coils, the smart insulation (SI) with a metal–insulator transition (MIT) materials, which have a resistivity variability on temperature, i.e., resistivity of MIT materials is decreased with temperature increase, may enhance not only the thermal stability but also current control performance of...
YBCO coated conductors are candidates for using in a number of High Energy Physics applications, like e.g. high field solenoids for muon colliders. A new approach in making YBCO magnets has been suggested recently, where the coils are neither insulated nor epoxied. It is believed that in this approach, the coil is much easier to protect, because once a given zone becomes normal, the lack of...