Study of model coils made of superconductor intended for the winding of the T-15 tokamak

Anashkin, I.O.; Klimenko, E. Yu.; Lelekhov, S.A.; Martovetskii, N. N.; Posadskii, I. A.

doi:10.1007/bf01132855

Cited by 7 publications

(1 citation statement)

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“…One of the first systematic observations of the correlation between the performance of the Nb 3 Sn conductors and degradation was the model coil effort on the T − 15 tokamak [8]. The T − 15 monolithic conductor was made by an electroplating deposition of copper on a Rutherford type cable with two copper tubes.…”

Section: Observation Of the Broadness Of Transition Correlation With ...mentioning

confidence: 99%

Correlation between degradation and broadness of the transition in CICC

Martovetsky¹

2013

Supercond. Sci. Technol.

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Cable in Conduit Conductor (CICC) performance is characterized in terms of relationships involving the electric field (E), voltage (V), temperature (T), current (I), magnetic field (B), and strain. Development of the electrical field in the V-T or V-I transitions in CICC is exponential, and in the coordinates log E vs T or log E vs I looks as a straight line.ITER Nb3Sn CICCs show degradation of properties versus load cycles that could be attributed to plastic deformation of the Nb3Sn strands or fracture of the superconducting filaments. The degradation is expressed in terms of reduction of the current sharing temperature Tcs or critical current Ic, respectively. It was noticed long ago that degradation is accompanied by a significant broadening of the V-T or V-I transition, that looks like a change in the slope in the semi-log coordinate plot. This paper presents some systematic observations of correlations between the critical parameters and broadness of the transition in many conductors tested in CICC. In most cases, the broadness of the transition seems to be a more sensitive indicator of the conductor damage even in cases when Tcs degradation is not clearly seen. Tcs degradation typically becomes obvious later in the cycling, especially after warm up and following cooldown and more cycling.In some cases, a CICC manifests temporary or even a permanent growth of Tcs with load cycles, especially in the latest measurements of the CS conductors with short twist pitches. A possible mechanism of degradation that allows qualitative explanation of this phenomenon is discussed, which is supported by the voltage measurements on the cable in TFUS1 with the voltage taps penetrating the jacket to the cable. IntroductionSince middle of 1990's, when an intensive development of the Nb3Sn CICC took place, a wealth of data on degradation of the high current Nb3Sn CICC has been developed. However, this knowledge has not yet produced a quantitative correlation that would allow predicting performance of the CICC from the properties of the strand, cabling pattern, void fraction and jacket properties and geometry.

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Section: Observation Of the Broadness Of Transition Correlation With ...mentioning

confidence: 99%