Fabrication and Testing of the 20 kA Binary Current Leads for the NHMFL Series-Connected Hybrid Magnet

Marshall, William; Bai, Hongyu; Bird, M.D.; Dixon, I.R.; Gavrilin, A.V.; Laureijs, Gideon A.; Lü, Jun; Ouden, A. den; Wijnen, Frans J. P.; Wulffers, Chris A.; Wulterkens, Gerben; Perenboom, J.A.A.J.

doi:10.1109/tasc.2016.2515544

Cited by 9 publications

(4 citation statements)

References 9 publications

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“…Two steady states are stable, indicated with a continuous curve, and one is unstable, marked with a dashed line. The source of the multiplicity is the nonlinear voltage-current relationship in Equation (5). To obtain a geometrical perspective of the multiplicity, the solution structure is schematically represented in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

“…Since the breakthrough discovery of Bednorz and Müller in 1986 [1], high-temperature superconductors (HTSs) have been extensively used in particle accelerators, tokamaks, and specialized high-field applications. The complexity and the development costs for such projects call for multi-national ventures across the globe [2][3][4][5][6][7][8][9][10]. An extensive summary of the active HTS current lead projects worldwide may be found in the work of Diev et al [10].…”

Section: Introductionmentioning

confidence: 99%

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Analysis of High-Temperature Superconducting Current Leads: Multiple Solutions, Thermal Runaway, and Protection

Krikkis¹

2023

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The multiple steady states of Ag/Bi2212-composite high-Tc superconducting leads modeling current delivery to a superconducting magnet have been numerically calculated. The model is based on longitudinal conduction combined with convective heat dissipation from a helium gas stream along the conductor. Because of the nonlinearities introduced by the voltage–current relationship and the temperature-dependent material properties, up to three solutions have been identified within the range of parameters considered. Linear stability analysis reveals that two of them are stable, i.e., the superconducting and the normal branches, while the remaining one is unstable. The limit points separating the stable from the unstable steady states form the blow-up threshold, beyond which any further increase in the operating current results in a thermal runway. Interesting findings are that for low filling ratios no bounded solution exists when the length of the lead exceeds the lower limit point, while very high maximum temperatures may be encountered along the normal solution branch. The effect of various parameters such as the conduction–convection parameter, the applied current, and the reduction in coolant flow (LOFA) on the bifurcation structure and their stabilization effect on the blow-up threshold are also evaluated. Apart from the steady and unsteady operating modes, the multiplicity analysis is also used to identify the range of the design and operating variables where safe operation, with a sufficient margin from the onset of instabilities, may beestablished, thus facilitating the protection of the leads and the device connected to it.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of High-Temperature Superconducting Current Leads: Multiple Solutions, Thermal Runaway, and Protection

Krikkis¹

2023

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“…The performance of the NHMFL current leads was successfully tested at HFML early 2015 in a dedicated test facility built for the purpose [23]. Especially the extremely stable temperature of 77 K of the HTS part at the liquid nitrogen intercept appears to be a virtue of this design and ensures very stable operation.…”

Section: Current Leadsmentioning

confidence: 99%

Progress in the Development of the HFML 45 T Hybrid Magnet

Ouden

Wulffers

Hussey

et al. 2016

IEEE Trans. Appl. Supercond.

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To extend its user's facilities, the High Field Magnet Laboratory (HFML-EMFL) at the Radboud University is in the process of building a 45-T hybrid magnet. The magnet system will consist of a 22 MW 32.7 T resistive insert and a 600-mmbore 12.3 T superconducting outsert magnet, and the design was significantly adjusted after a thorough design revision in 2011. The HFML hybrid magnet will be operated with separate current sources for the superconducting and resistive coils (20 kA at 10 V and 40 kA at up to 550 V, respectively). The outsert coil is a solenoid layer wound with all-Nb 3 Sn/Cu cable-in-conduit conductor (CICC), cooled by a forced flow of supercritical helium and operated at 20 kA. Similar to the series-connected hybrids for the HZB (Berlin, Germany) and the NHMFL (Tallahassee, FL, USA), the HFML outsert coil contains three grades of conductor. All CICC grades are based on high-current density Nb 3 Sn strand produced by Oxford Superconducting Technology. The CICC production and qualification program has been completed successfully. The coil will be wound at the NHMFL and, after heat treatment and impregnation, sent to Nijmegen for integration into the cryostat. In this paper, the design choices and current status of the program are presented. IndexTerms-CICC, high field magnet, Nb 3 Sn superconductivity. I. INTRODUCTIONT HE High Field Magnet Laboratory at the Radboud University Nijmegen (HFML, partner in the European Magnetic Field Laboratory, EMFL) is developing a 45 T hybrid magnet system, which will consist of a solenoidal 12.3 T Nb 3 Sn-CICC based superconducting outer magnet (outsert) and a 32.7 T Florida-Bitter type resistive inner magnet (insert) with a useful warm bore of 32 mm [1], [2]. After a thorough design review in

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“…HTS binary current leads were first proposed by Mumford in 1989 [3]. In the past few years, HTS binary current leads have been widely applied, not only in large-scale systems, such as particle accelerators [4][5][6][7] and fusion devices [8][9][10][11][12][13], but also for smaller isolated magnets, such as superconducting magnetic resonance imaging (MRI) magnets [14,15], high-field magnet system [16][17][18][19][20][21] and other special test facilities [22][23][24][25][26][27][28][29][30]. The typical structure of binary current leads comprises two parts: a hightemperature portion made by a normal conductor and a lowtemperature portion made by an HTS and a normal metal shunt.…”

Section: Introductionmentioning

confidence: 99%

The design of YBCO binary current leads and its electromagnetic-thermal coupling analysis based on PEEC and finite volume method

Zheng

Liu

Song

et al. 2023

Supercond. Sci. Technol.

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A superconducting magnet system is developed for the application of high frequency gyrotrons at XXX. The operation cost for the magnet is dominated by refrigeration power. To reduce the heat load for cryogenic system, a pair of YBCO binary current leads is designed in consideration of the industrial concentration on type II high temperature superconducting (HTS) YBCO material. In this paper, a simulation model is proposed to perform the electromagnetic-thermal coupling analysis of these YBCO binary leads under different operation conditions by combining Partial Element Equivalent Circuit (PEEC) method and Finite Volume Method (FVM). The simulation code can improve computational efficiency and enable high-accuracy coupling between the electromagnetic field and heat transfer process. Under steady state, the heat leakage at 4.2 K cold end of YBCO binary leads depends mainly on the geometric parameters of YBCO tape, especially the cross-sectional area of the copper layer in YBCO tape. The cooling mode and liquid helium level also have a significant impact on the heat leakage level. The optimal outer diameter of the normal copper section is identified, and the optimum value is largely influenced by the effective cooling power imposed on the cold end of the normal copper section. Under transient state, the simulation for charging process and the loss of cooling accident are performed, along with the detailed analysis of the electromagnetic-thermal response features of the leads under these conditions. The results indicate that the YBCO binary current leads possess high thermal stability and an ample time margin for the magnet system to be demagnetized.

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Fabrication and Testing of the 20 kA Binary Current Leads for the NHMFL Series-Connected Hybrid Magnet

Cited by 9 publications

References 9 publications

Analysis of High-Temperature Superconducting Current Leads: Multiple Solutions, Thermal Runaway, and Protection

Analysis of High-Temperature Superconducting Current Leads: Multiple Solutions, Thermal Runaway, and Protection

Progress in the Development of the HFML 45 T Hybrid Magnet

The design of YBCO binary current leads and its electromagnetic-thermal coupling analysis based on PEEC and finite volume method

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