Performance measurements of superconducting current leads with low helium boil-off rates

Niemann, R. C.; Cha, Y.S.; Hull, J.R.

doi:10.1109/77.233727

Cited by 15 publications

(6 citation statements)

References 6 publications

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“…In our experimental program to measure the performance of HTS leads [18], we discovered that pressure fluctuations within the dewar could cause significant changes in the measured helium boil-off rate. Such fluctuations in a commercial system could profoundly affect boil-off dynamics, and the system should be designed for such possibilities.…”

Section: Conclusion C Pressure Fluctuationsmentioning

confidence: 99%

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High-temperature superconducting current leads

Hull

1993

IEEE Trans. Appl. Supercond.

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Use of high-temperature superconductors (HTSs) for current leads to deliver power to devices at liquid helium temperature, now near commercial realization, has the potential to reduce refrigeration requirements and helium boil-off to values significantly lower than the theoretically best values achievable with conventional leads. Considerable advantage is achieved by operating these leads with an intermediate-temperature heat sink. The HTS part of the lead can be made from pressed and sintered powder. Powder-in-tube fabrication is also possible, but the normal metal part of the lead acts as a thermal short and cannot provide much stabilization without increasing the refrigeration requirement. For lead stability, designs with low current density are favored. Such leads can be manufactured with today's technology, and refrigeration requirements are lower for the same allowable burnout time. Higher current densities result in lower boil-off for the same lead length, but burnout times can be very short. In comparing experiment to theory in open systems, the density of helium vapor must be accounted for in calculating the expected boil-off. For very-low-loss leads, two-dimensional heat transfer and the state of the dewar near the leads may play dominant roles in lead performance.

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Section: Conclusion C Pressure Fluctuationsmentioning

confidence: 99%

“…Almost all analyses of selfthe heat entering the liquid he where CL is the latent heat experimental program to ac low-loss HTS leads [18], what m is being measured. constant pressure), Cha et approximation is given by…”

Section: Gas Density Correctionmentioning

confidence: 99%

High-temperature superconducting current leads

Hull

1993

IEEE Trans. Appl. Supercond.

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“…Conduction losses for HTS current leads have been obtained neglecting heat exchange with helium gas evaporating from the bath; a more detailed consumption computation needs to consider this heat exchange [4], [5].…”

Section: Calculated Thermal Leakmentioning

confidence: 99%

Cryocooler assisted cryostat for a 4 T split-coil NbTi magnet

Petrillo

Ariante

Mariani

et al. 2002

IEEE Trans. Appl. Supercond.

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A cryocooler assisted cryostat for a 4 T split-coil NbTi magnet operated in liquid helium bath is under development at the ANSALDO-CRIS.A two stage GM cryocooler (1st stage 15 W @ 45 K, 2nd stage 5 W @ 15 K) is used for the cooling of two radiation shields at temperatures less than 45 K and 15 K respectively.For magnet charge, a couple of 100 A vapor cooled HTS current leads, based on Bi-2223/AgAu tapes, operates between the 1st stage of cryocooler and the helium bath.AlN plates have been used to obtain a good thermal contact electrically insulated between HTS lead and cryocooler.The developed configuration allows to eliminate liquid nitrogen cooled radiation shields and to minimize static liquid helium consumption. Calculated and measured system performances are compared.

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“…The 2212 material is being fabricated for applications as current leads in superconducting magnets and for current interrupters [1,2,3]. The YBCO material has also been used for current leads for both SMES [4] and for superconducting magnets [5]. The most impressive performance of the YBCO material at 77 K has been obtained by the group in Texas [6,7,8].…”

Section: Introductionmentioning

confidence: 99%

High Tc monolithic helical magnets

et al. 1996

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Helical magnets have been manufactured of both high Tc and low Tc materials. The helical magnets are manufactured from solid hollow cylinders. A helix is machined in the cylinders, resulting in one-layer solenoids. In this paper, results of a BSCCO 2212 helical magnet are discussed. The magnet has been tested in fields up to 15 T. Stability, quench protection, and critical parameters have been determined. Results of local heating of the magnet, and the resulting quench propagation, have been studied. A distributed method of quench protection has been tested. The results may be used for quench protection of large high-Tc magnets. The details of the testing are described.

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Performance measurements of superconducting current leads with low helium boil-off rates

Cited by 15 publications

References 6 publications

High-temperature superconducting current leads

High-temperature superconducting current leads

Cryocooler assisted cryostat for a 4 T split-coil NbTi magnet

High Tc monolithic helical magnets

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