Overview of results from Wendelstein7-X HTS current lead testing

Drotziger, S.; Buscher, Klaus-Peter; Fietz, W.H.; Heiduk, M.; Heller, R.; Hollik, M.; Lange, Christian; Lietzow, R.; Moennich, Thomas; Richter, T.; Rummel, Thomas

doi:10.1016/j.fusengdes.2013.01.104

Cited by 17 publications

(4 citation statements)

References 10 publications

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“…The average losses before starting current operation are estimated to be (7.03±3.43) W. The results obtained so far are compared to those from the acceptance test [9]. While the total resistance along the HTS module estimated from the data taken during plasma operation are in nice agreement to the results obtained during the acceptance tests, the average losses measured before starting the current operation are much larger than the zero current losses measured for each current lead at KIT.…”

Section: Description Of Superconducting Coil and Auxil-iary Systemssupporting

confidence: 53%

Operation Experience of the Wendelstein 7-X High-Temperature Superconductor Current Leads

Heller

Bau

Nagel

et al. 2019

IEEE Trans. Appl. Supercond.

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The fusion device Wendelstein 7-X (W7-X) is a modular stellarator which went into operation at the Greifswald branch of the Max-Planck-Institut für Plasmaphysik in December 2015. The main component is the superconducting magnet system which consists of 50 nonplanar and 20 planar coils, 14 high temperature superconductor (HTS) current leads (CLs), and more than 100 superconducting bus bars. The HTS CLs with a maximum current of 18.2 kA were constructed, tested and delivered by the Karlsruhe Institute of Technology (KIT). In the first plasma physics campaign the nonplanar coils were operated with a maximum current of 12.4 kA while the planar coils were energized up to 4.9 kA. The paper describes the performance of the HTS CLs during plasma operation. A comparison to the acceptance test results performed after the construction of the CLs at KIT will be presented.

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Section: Description Of Superconducting Coil and Auxil-iary Systemssupporting

confidence: 53%

Operation Experience of the Wendelstein 7-X High-Temperature Superconductor Current Leads

Heller

Bau

Nagel

et al. 2019

IEEE Trans. Appl. Supercond.

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“…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%

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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“…All superconducting magnets and all current leads were tested separately under cryogenic conditions up to the nominal current in the self field directly after fabrication [10]- [12]. Nevertheless the integral commissioning of one coil circuit comprises also additional components like the power supply, the room temperature bus bars, the flexible copper braids at the transition to the warm side of the two current leads, 11 superconducting bus bars which connect coils with each other and with the current leads.…”

Section: A Strategy and Organizationmentioning

confidence: 99%

Commissioning Results of the Superconducting Magnet System of Wendelstein 7-X

Rummel

Nagel

Bykov

et al. 2017

IEEE Trans. Appl. Supercond.

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The superconducting fusion device Wendelstein 7-X (W7-X) went into operation in December 2015. One of the most important steps was the commissioning of the superconducting magnet system. It consists of 70 superconducting coils, 14 HTS current leads, and more than 100 superconducting bus bars. The system is divided into seven electrical circuits with ten coils, associated bus bars and two current leads each. The commissioning of the magnet system was performed in two major steps: In a first step the seven coil circuits were separately energized and operated at several current levels in a range between 2 kA and 12.8 kA. In a second step all seven circuits were operated together. The adjustment of the quench detectors, the evaluation of the thermal and mechanical behavior, and the test of the magnet safety system were further work packages. Fast discharges were initiated to check the proper behavior of the magnet safety system. Steady-state operation of up to eight hours was performed to adjust the helium mass flows. The commissioning was successfully completed, the main goal of the magnet system is fully reached, which is also confirmed by magnetic flux measurements and the results of the first plasma operation.

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Overview of results from Wendelstein7-X HTS current lead testing

Cited by 17 publications

References 10 publications

Operation Experience of the Wendelstein 7-X High-Temperature Superconductor Current Leads

Operation Experience of the Wendelstein 7-X High-Temperature Superconductor Current Leads

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

Commissioning Results of the Superconducting Magnet System of Wendelstein 7-X

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