The main aim of the EU H2020 project EcoSwing was to demonstrate a technical readiness level of 6–7 for high-temperature superconducting (HTS) technology operating in a wind generator. To reach this goal, a full-scale synchronous HTS generator was successfully designed, built and field-tested in a 3.6 MW turbine. The generator has a rotor with 40 superconducting coils of 1.4 m long. The required >20 km of coated conductor was produced within the project’s time schedule. All coils were tested prior to assembly, with >90% of them behaving as expected. The technical readiness level of HTS coils was thus increased to level 7. Simultaneously, the maturing of cryogenic cooling technology over the last decade was illustrated by the several Gifford-McMahon cold-heads that were installed on-board the rotor and connected with the stationary compressors through a rotating coupling. The cryogenic system outperformed design expectations, enabling stable coil temperatures far below the design temperature of 30 K after only 14 d of cool-down. After ground-based testing at the IWES facility in Bremerhaven, Germany, the generator was installed on an existing turbine in Thyborøn, Denmark. Here, the generator reached the target power range and produced power for over 650 h of grid operation.
Numerous manufacturers and different strand processing techniques are involved with the production of the Nb 3 Sn strand material required for ITER. The superconducting transport properties of brittle Nb 3 Sn layers strongly depend on their strain state. Hence, the thermal compression and the substantial transverse load in combination with the key choice for the cabling pattern of the CICCs, will determine their performance. Knowledge of the influence of axial strain, periodic bending, and contact stress on the critical current ( c ) of the used Nb 3 Sn strands is inevitable to gain sufficient confidence in an economic design and a stable operation of ITER. We have measured the c and -value of Nb 3 Sn strands from various manufacturers in the TARSIS facility, when subjected to spatial periodic bending and contact stress. The c and -values have been determined for applied axial compressive and tensile strain varying from 0.8% up to +0.5%, between = 4 2 K and 10 K and = 6 T to 14 T. The strain sensitivity varies appreciably for different strand types. We present a selection of the results obtained so far.
Abstract-EUCARD2 aims to research ReBCO superconducting magnets for future accelerator applications. The properties of ReBCO conductors are very different from low temperature superconductors. To investigate dynamic field quality, stability and normal zone propagation an electrical network model for coated conductor cables was developed. To validate the model two identical samples were prepared at CERN after which measurements were taken at the University of Twente and Southampton University. The model predicts that for Roebel cable, in a changing magnetic field applied in the perpendicular direction, the hysteresis loss is much larger than the coupling loss. In the case of a changing magnetic field applied parallel to the cable coupling loss is dominant. In the first case the experiment is in good agreement with the model. In the second case the data can only be compared qualitatively because the calibration for the inductive measurement is not available.
-Last year a record central field of 11 T at first excitation at 4.4 K has been achieved with the experimental LHC model dipole magnet MSUT by utilising a high J , powderin-tube Nb3Sn conductor. This is the first real breakthrough towards fields well above 10 T at 4 K. The clear influence of magnetisation and coupling currents on the field quality, the quench behaviour and the temperature development in the coils has been measured and is discussed. For application in highfield accelerator magnets (10-15 T dipoles, 300-400 T/m quadrupoles) these experimental results clearly reveal the potential, the present limitations and the necessary improvements of Nb,Sn technology with respect to strand, cable and coil design and manufacturing. A brief review of developments in this field is presented. The focus is on accelerator dipole magnets but the key issues for quadrupole magnets are quite similar On strand and cable level the key issues comprise the reduction of I,. due to cabling (Silament damage), transverse stress sensitivity of .Ic, the istill existing controversy of a high J,. versus filament size, heat resistant and thermally conductive electrical insulation, control of the interstrand crossing and adjacent resistances R,. and R,, in relation to the thermal and electrical stability and the low normal zone propagation.To illustrate the present status and the potential of Nb3Sn accelerator magnets, the experimental results of the successful program to realise a 1 meter 11 T single aperture Nb$n dipole magnet MSUT are discussed. In this program the emphasis has been put on the main challenge, namely to increase the field strength by exploiting the high J, of the powder-in-tube Nb3Sn conductor [4] and developing Nb3Sn dedicated design and manufacturing concepts. I. INTRODUCTION 11. MSUT SYSTIEM CHARACTERISTICS The development of accelerator magnets (dipoles and quadrupoles) is focused on high-field strength c.q. high current density, field quality (normalised higher order muItipoles < I 0-4), reliable operation (mechanical and thermal stability) and high quality large scale production. The present practical field limit for NbTi magnets operating at 2 K amounts to about 8.5 T. The relation between design and manufacturing parameters and the quench behaviour (location, ageing and thermal cycling effects, thermal or mechanical limitations) is not well understood yet [ I], which impedes large scale production. The amplitude and the time dependent behaviour of the undesired higher order multipoles as well as the ramp rate sensitivity can be described quite well by modelling the interstrand coupling currents and the boundary induced coupling currents [2]. The necessary control of these currents and the consequences for cable stability is still under investigation [3].To attain a field of 10-15 T presently only Nb3Sn conductors, operating at 4.4 K, are available in satisfactory quality and quantity. Apart Srom the general issues concerning highfield accelerator magnets mentioned above, typical Nb3Sn related diffic...
Measurements have been made of the critical current on an Nb3Sn superconducting strand destined for the ITER (International Thermonuclear Experimental Reactor) prototype cable-in-conduit conductors. Characterization of the strand was performed on a recently developed spring device, named Pacman, allowing measurements of the voltage–current characteristic of an Nb3Sn strand over a wide range of applied axial strain, magnetic field, temperature and currents up to at least 700 A. The strand was measured in a magnetic field between 4 and 11 T, temperatures of 4.2–10 K and applied axial strain ranged from −0.9% (compressive) to +0.3% (tensile). The critical currents were then used to derive the superconducting and the deformation-related parameters for the scaling of measured results, based on the so-called ‘improved’ deviatoric strain model. We also demonstrate that the same values can be derived from a partial critical-current data set without spoiling the overall scaling accuracy. This indicates that the proposed scaling relation can be used not only as a fitting tool, but is promising for reliable extrapolation as well, providing substantial savings in cost and time for the experimental routine.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.