Test results of a 1 kA (2 kA)-20 kV HTSC current lead model

Herrmann, P.F.; Beghin, E.; Bottini, Gabriella; Cottevieille, C.; Leriche, Anne; Verhaege, T.; Böck, J.

doi:10.1016/0011-2275(94)90216-x

Cited by 30 publications

(8 citation statements)

References 10 publications

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“…Several prototypes of current leads of the 1 -2 kA class have been designed and tested [3][4][5]. The results were encouraging although the refrigeration power was not as low as given above.…”

Section: Introductionmentioning

confidence: 66%

Conceptual design of a forced-flow-cooled 20-kA current lead using Ag-alloy-sheathed Bi-2223 high-temperature superconductors

Heller

Hull

1994

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The use of high-temperature superconductors in current leads lo reduce refrigeration power has been investigated by many groups in the past. Most used YBCO and Bi-2212 bulk superconductors, although their critical current density is not very high. In this paper, Bi-2223 HTSC tapes sheathed with Ag alloys are used in the design of a 20-kA current lead because of their higher critical current in medium magnetic fields. The lead current of 20 kA is related to the coil current of the planned stellarator WENDELSTEIN 7-X. Forced-flow helium cooling has been used in the design, allowing position-independent and well-controlled operation. The design characteristics of the lead are presented and 4-K helium cooling of the whole lead, as well as 60-K helium cooling of the copper part of the lead, is discussed. The power consumption at zero current, and the lead's behaviour in case of loss of coolant flow, are given. The results of the design allow extrapolation to current leads of the 50-kA range. Konzeptioneller

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Section: Introductionmentioning

confidence: 66%

Conceptual design of a forced-flow-cooled 20-kA current lead using Ag-alloy-sheathed Bi-2223 high-temperature superconductors

Heller

Hull

1994

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“…Whereas for normal metals the Wiedemann-Franz relation between electrical and thermal conduction results in a universal minimum value ~ 1 W/kA for charge transport to a 4 K heat load, HTS in the superconducting state offer a large current capability at the low thermal conductivity of oxide ceramics [46]. Bi-2212 bulk based leads demonstrated a reduction of the 4 K heat load by a factor ~ 5 compared to conventional leads in dc as well as in ac application [47,48]. Current leads based on Bi-2223 tapes with AgAu alloy sheath (with one order of magnitude lower thermal conductivity compared to Ag) achieve similar performance [49].…”

Section: Magnetsmentioning

confidence: 99%

Application Fields of High-Temperature Superconductors

Hott

2004

High Temperature Superconductivity 2

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“…Recently, s e v d HTSC c m t leads have been constmcted and tested [7]- [9]. Most of the HTSC leads were designed by iterative calculations for a particular case [ lo].…”

Section: Htroducfionmentioning

confidence: 99%

Design chart of high temperature superconducting gas cooled current leads

Maehata

Nishioka

Ishibashi

et al. 1995

IEEE Trans. Appl. Supercond.

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General design equations derived from one dimensional energy balance equations are solved to evaluate generalized characteristics of gas cooled current leads which are made of high temperature superconducting (HTSC) material. Design parameters of the conductor and the cooling channel are combined into a single general cooling parameter with the consideration of laminar flow. Generalized characteristics of HTSC current leads, namely the heat fiow from the cold end of the leads, the geometrical dimension of the conductor and the pressure drop of the cooling gas are represented in a design chart with the general cooling parameter. Thermal runaway of the conductor is analyzed for various geometrical dimensions in the case of stoppage of the cooling gas with the consideration of the quench propagation. The temperature rise time works as a criterion for determining the g e e metrical dimension. By determining the geometrical dimension according to the criterion, the heat flow from the cold end is estimated to be less than 0.lmWIA I. hTRODUCFIONSuperconducting magnets are operated by supplying the electric current through cufTent leads fiom the power supply at the room temperature. Usual cryogenic systems for superconducting magnets employ conventional copper current leads, which are made of copper material. Conventional current leads are cooled by cold helium gas and optimized to minimize the heat leak into the low temperature region with the consumption of cooling gas flow as small as possible. The usual design procedure requires iterative and complicated calculation to evaluate such operational characteristics as the heat le& as a function of the geometry of the conductor, the pressure drop of the cooling gas and the temperature rise time of the conductor during the thermal runaway[l],[2]. To simplify the design procedure, we developed a generalized design method. In this method, the characteristics of leads, such as the heat leak, the geometrical dimension of the conductor and the pressure drop of the cooling gas, were obtained in the generalized form and summarized in a design chart [3]. Sevea-al current leads were designed by the use of the design chart and exhibited good operational performance[4], [5]. Even in the case of an ideal heat exchange, optimum copper leads has a lower limit of the heat leak of -1 .O mW/A[ 11.Because of the generation of no Joule heating and very low thermal conductivity, high temperature superconducting (HTSC) material has a possibility of the application to current leads which reduce the lower limit of the heat leak of the Manuscript received October 17, 1994. This work was supported in part bv Inoue Foundation for Science. NOMENCLATURE C Specific heat of conductor (J w1 R I ) C Specific heat of helium gas (J k') d8 Hydraulic diameter i. e. d = 4sdf(m) f Cooling perimeter (m) F f m d z e d by current ( d A ) G m per unit area in cooling channel (kg m-2 8") Z Current (A) 1 Conductor length effective for heat exchange (m) m Mass flow rate of cooling gas @g i ' ) M m normalized by curren...

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Test results of a 1 kA (2 kA)-20 kV HTSC current lead model

Cited by 30 publications

References 10 publications

Conceptual design of a forced-flow-cooled 20-kA current lead using Ag-alloy-sheathed Bi-2223 high-temperature superconductors

Conceptual design of a forced-flow-cooled 20-kA current lead using Ag-alloy-sheathed Bi-2223 high-temperature superconductors

Application Fields of High-Temperature Superconductors

Design chart of high temperature superconducting gas cooled current leads

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