Effect of Cyclic Loading and Conductor Layout on Contact Resistance of Full-Size ITER PFCI Conductors

Ilyin, Y.; Nijhuis, A.; Abbas, Wouter; Bruzzone, P.; Stepanov, B.; Muzzi, L.; Gislon, P.; Zani, L.

doi:10.1109/tasc.2005.849088

Cited by 34 publications

(46 citation statements)

References 8 publications

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“…These confirmed that the asymptotic value of the coupling loss constant is of the order of 50 ms, in the range of the value expected from measurements on short samples [13] and well within the range acceptable from the point of view of heat removal.…”

Section: Discussionsupporting

confidence: 84%

“…The coupling loss measured in a short piece of the final conductors (400 mm) was found to be a strong function of the number of mechanical loading cycles under a transverse force of 315 kN/m [13], which is in the range of the maximum expected mechanical load from Lorentz forces in the ITER PF coils (270 to 330 kN/m). The initial product of demagnetization factor and coupling time constant , around 15 ms in virgin state, decreased to less than 10 ms in the first 100 cycles, to increase again above 40 ms after 10,000 cycles.…”

Section: The Pf Conductor Insertmentioning

confidence: 95%

“…Further details on the coil design [6], strand and cable manufacturing [7]- [11], coil manufacturing [12], short sample test results [5], [13], and supporting analyses to the insert test [14]- [17] can be found in the extensive list of references quoted. [19], [20], with the necessary adaptations to the different operating conditions and PF conductor characteristics [15].…”

Section: The Pf Conductor Insertmentioning

confidence: 99%

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Test Results From the PF Conductor Insert Coil and Implications for the ITER PF System

Bessette

Bottura

Devred

et al. 2009

IEEE Trans. Appl. Supercond.

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Abstract-In this paper we report the main test results obtained on the Poloidal Field Conductor Insert coil (PFI) for the International Thermonuclear Experimental Reactor (ITER), built jointly by the EU and RF ITER parties, recently installed and tested in the CS Model Coil facility, at JAEA-Naka. During the test we (a) verified the DC and AC operating margin of the NbTi Cable-in-Conduit Conductor in conditions representative of the operation of the ITER PF coils, (b) measured the intermediate conductor joint resistance, margin and loss, and (c) measured the AC loss of the conductor and its changes once subjected to a significant number of Lorentz force cycles. We compare the results obtained to expectations from strand and cable characterization, which were studied extensively earlier. We finally discuss the implications for the ITER PF system. Index Terms-Cable-in-conduit conductors, fusion reactors, Nb-Ti superconducting material, superconducting magnets. I. BACKGROUND ON ITER PF CONDUCTORST HE ITER Poloidal Field (PF) conductors have undergone a significant evolution in the past years. In the original ITER design (2001) the Cable-in-Conduit Conductors (CICCs) were optimized to match the current/field levels in each of the six PF coils [1]. Following recent design reviews, a number of modifications have been introduced [2], leading to the conductor designs detailed in Table I, for the envelope of operating conditions in the PF Coils reported in Table II. The main change with respect to the original design is a reduction in the Cu:nonCu ratio of the low field conductors (PF2 to PF5), implying that the Stekly condition of cryogenic stability [3] is no longer respected. Experiments on subsize conductors [4] have suggested that in the planned regime of operation, and for the expected perturbation spectrum, full cryostability (i.e. a copper fraction corresponding to the Stekly limit) is excessive. In fact, for the conditions considered, it is more convenient to design the conductor for larger temperature margin, increasing the fraction of Nb-Ti, while maintaining the copper fraction to the strict minimum demanded for protection. To achieve the operating requirements of Table II, two main conditions must be met. Firstly, the cable performance must be close to the sum of the projected performance of the individual strands, without the occurrence of the premature quenches often seen in large size Nb-Ti conductors and attributed to current non-uniformity [4], [5] (see also later discussion). In practice, we quantify this first condition using the temperature margin above the operating temperature. The design value of the temperature margin is 1.5 K, with a maximum uncertainty of 0.5 K, which results in a minimum acceptable margin of 1 K.Secondly, all AC loss sources in the cable must be controlled, so to limit the temperature increase due to the heating due to the pulsed operation. In particular, the product of the cable demagnetization factor and coupling time constant, , proportional to coupling loss, must be smalle...

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Section: Discussionsupporting

confidence: 84%

Section: The Pf Conductor Insertmentioning

confidence: 95%

Section: The Pf Conductor Insertmentioning

confidence: 99%

See 1 more Smart Citation

Test Results From the PF Conductor Insert Coil and Implications for the ITER PF System

Bessette

Bottura

Devred

et al. 2009

IEEE Trans. Appl. Supercond.

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“…In principle, the solution of the concerned 'normal equation' depends on the choice of an annular position of the petals inside the conduit. Since this position is unknown (and correlation between locations is poor due to variation in the cable twist pitch with length [12]), the solution in all three locations has been found for any combination of the rotation angles between 0 and 60 (the limits are due to periodicity of the solution) in both conductors. Then for each angle we have found an overloaded petal with the maximum deviation from the average current per petal.…”

Section: A Six-petals Problem Low Currentmentioning

confidence: 99%

“…6, the temperature increase causes a change in the self-field profile in all three locations along both conductors. Most likely the current redistribution happens through the joints as having lower contact resistances compared to inter-petal contact resistances [12] and hardly along the length, in particular for the sample with petal wraps. It is also confirmed by the resistance rise over the termination in the (see Fig.…”

Section: A Six-petals Problem Low Currentmentioning

confidence: 99%

Reconstruction of Current Unbalance in Full-Size ITER NbTi CICC by Self-Field Measurements

Ilyin

Nijhuis

Kate

et al. 2005

IEEE Trans. Appl. Supercond.

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Abstract-Methods have been developed to study the distribution of the transport current among the strand bundles of cable-in-conduit conductors (CICC) by using self-field measurements with Hall probe arrays. The unbalance in the transport current is mainly caused by the unavoidable nonuniformity of the joints and can be a reason for a change in the voltage-temperature characteristic and consequently of the temperature margin. In the present study we focus on the reconstruction of the current unbalance in a full size NbTi CICC tested in the SULTAN test facility. The crucial point in the reconstruction procedure is the proper choice of the reference self-field profile corresponding to a uniform current distribution. To achieve this uniform distribution, the conductors were driven far into the current sharing regime. The self-field profile corresponding to the highest achieved voltage level was taken as a reference. This assumption is supported by the modeling of current-sharing runs in the CUDI-CICC network model. Furthermore, local redistribution effects were observed in the conductors at high currents. The current transfer associated with this redistribution is analyzed as well.

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AC Loss of ITER Feeder Busbar in 15MA Plasma Current Reference Scenario

Rong

Huang

2015

J Fusion Energ

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Effect of Cyclic Loading and Conductor Layout on Contact Resistance of Full-Size ITER PFCI Conductors

Abstract: As a final goal, the test outcome will be used as a reference for calibration of the PFCI AC loss performance.

Cited by 34 publications

References 8 publications

Test Results From the PF Conductor Insert Coil and Implications for the ITER PF System

Test Results From the PF Conductor Insert Coil and Implications for the ITER PF System

Reconstruction of Current Unbalance in Full-Size ITER NbTi CICC by Self-Field Measurements

AC Loss of ITER Feeder Busbar in 15MA Plasma Current Reference Scenario

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