Error Estimation in the $T_{cs}$ Measurement of TF Conductors in the SULTAN Facility

The performance of the toroidal field (TF) magnet conductors for the ITER machine are qualified by a short full-size sample (4 m) current sharing temperature (Tcs) test in the SULTAN facility at CRPP in Villigen, Switzerland, using the operating current of 68 kA and the design peak field of 11.8 T. Several samples, including at least one from each of the six ITER Domestic Agencies participating in TF conductor fabrication (China, European Union, Japan, Russia, South Korea and the United States), have been qualified by the ITER Organization after achieving Tcs values of 6.0–6.9 K, after 700–1000 electromagnetic cycles. These Tcs values exceed the ITER specification and enabled the industrial production of these long-lead items for the ITER tokamak to begin in each Domestic Agency. Some of these samples did not pass the qualification test. In this paper, we summarize the performance of the qualified samples, analyze the effect of strand performance on conductor performance, and discuss the details of the test results.

Section: Acceptance Criterionmentioning

confidence: 73%

Section: Dispersion Of the Voltage Tap Signalsmentioning

confidence: 99%

Results of the TF conductor performance qualification samples for the ITER project

Breschi

Devred

Casali

et al. 2012

“…This crucial experimental data is of course affected by some measurement error. It was shown in a previous studies [27] that this error can be correlated to the difference in current sharing temperature measured by individual voltage taps of the voltage tap crown mentioned above. The maximal difference in the current sharing assessment between the various voltage taps of the crown has been computed for all runs of each conductor.…”

Section: Assessment Of the Current Sharing Temperaturementioning

confidence: 88%

Performance tests of ITER CS conductor samples from series production

Breschi

Devred

Macioce

et al. 2023

The ITER magnet system is one of the most sophisticated superconducting magnet systems ever designed, with a stored energy of 51 GJ. The coils are wound from Cable-in-Conduit Conductors (CICCs) made of superconducting and copper strands assembled into a multistage rope-type cable, inserted into a conduit of austenitic steel tubes. The ITER Central Solenoid (CS) works in pulsed mode, reaching a peak field of 13 T, thus allowing the induction of a high intensity current in the plasma of the ITER tokamak. This magnet consists of a stack of six modules which include around 125 t of Nb3Sn strands. The production of all CS conductors has been completed and module manufacturing is well underway; throughout the production phase, samples were cut at the extremities of the conductor unit lengths to undergo quality control tests. About 25% of the conductor short samples were tested in current and field at cryogenic conditions at the SULTAN facility in Villigen, Switzerland. This work reports the comparative analysis of the short samples set of test results.

“…As already presented in [15] and [24,25] for the previous test campaigns on the TF conductors, a pair of about 2.4 m long Cable in Conduit Conductors (CICC), commonly named left and right leg, are introduced in the bore of a magnetic system of the SULTAN facility. The background DC field is generated by 6 pairs of split solenoids which allow reaching a peak background field up to 10.8 T. The length of the peak field region (indicated here as High Field Zone, HFZ) is 450 mm at 1% homogeneity.…”

Section: Description Of the Test Campaignmentioning

confidence: 99%

Impact of mechanical and thermal cycles at different operating conditions on the ITER toroidal field coil conductor performance

Breschi¹,

Cavallucci²,

Tronza³

et al. 2021

The impact of electromagnetic (EM) and thermal cyclic loading (referred as warm-up-cool-down—WUCD) on the Nb3Sn cable in conduit conductors for the toroidal field magnets of the ITER tokamak should be carefully assessed for the proper operation of the machine. The experience gained during the production phases of the TF conductors revealed that a degradation occurs when thermal and EM cyclic loading is applied at the nominal operating conditions of 10.78 T and 68 kA. Since at the beginning of the tokamak operation the nominal conditions will not be achieved, it is worth investigating to what extent lower EM loads affect the conductor performance, and the threshold of EM load that triggers the WUCD degradation. The aim of this investigation is to identify critical levels which determine the onset of this degradation, both in terms of thermal and EM cycles, and to study the performance of strands from different suppliers. For this assessment, a set of conductor samples were manufactured including all types of strands to be used in the TF coils of the ITER machine. These samples were subjected to a set of EM and thermal cycles representing in a realistic way the actual operation of the conductors in the ITER machine. The tests were performed in the SULTAN facility of the Swiss Plasma Center at working conditions ranging from 5.4 T–34 kA to 10.78 T–68 kA. This work presents the results obtained in these tests in terms of current sharing temperature (T cs), effective strain, rate of degradation at different working conditions and their implications for the prospected conductor performance in the machine.