Coupled mechanical–electromagnetic–thermal–hydraulic effects in Nb₃Sn cable-in-conduit conductors for ITER

Abstract

The crucial multi-physics problem of how to extrapolate from the performance of an isolated Nb 3 Sn strand measured in the laboratory to the performance of a superconducting coil using multi-strand twisted cables is addressed here. We consider the particular case of the path going from the LMI strand to the international thermonuclear experimental reactor (ITER) toroidal field model coil (TFMC), through its associated Full Size Joint Sample, the TFMC-FSJS. Mechanical, electromagnetic and thermal-hydraulic conditions are simulated using the ANSYS, ENSIC and Mithrandir/M&M codes, respectively. At least in this case, the DC performance of the short sample turns out to be relatively close to (considering error bars) but not fully representative of that of the coil, showing higher (less compressive) effective thermal strain but also higher sensitivity to the electromechanical load.

Quality control in the design, fabrication and operation of the ITER magnets

“…[15,16] and some of the latest interpretations in Refs. [7,8,13]. Because the conductor has undergone some modifications to improve performance after the results from these tests, a performance re-verification is required for the various combinations of strand, cable layout and jacket type used in the ITER coils.…”

“…However this sample does not reflect the coil operating conditions, due to the lack of operating strain and the proximity of the end joints to the high field, and it is necessary to link the short sample results to those of the model coils to enable an appropriate correction to be made. Such link is available from the model coils for one Incoloy conductor from the CSMC and one with a steel jacket from the TFMC [7,8]. The comparison shows some unexplained discrepancies which have to be covered by an adequate margin in the design, although this carries a cost penalty.…”

Numerical investigation on transverse heat transfer properties in cross section of full size Nb3Sn CICC ITER conductor

“…[1][2][3][4] The predictions on the macroscopic performance of cable involving mechanical, electromagnetic and thermodynamic properties under the complex multi-field coupled effects have been the matter of people's concern. [5][6][7] The investigations of mechanical properties of cables under transverse electromagnetic loads have been tried and studied by many researchers. [8][9][10][11] However, the main factors that affect the thermodynamic behavior in the cross section of this complex geometry are still not well understood.…”

Comparison of Critical Current Versus Axial Strain Measurements on Internal Tin <inline-formula> <tex-math notation="TeX">$\hbox{Nb}_{3}\hbox{Sn}$</tex-math></inline-formula> Strand at ASIPP and University of Twente

“…The transport properties of the superconductors might be changed under the influence of stress [1]- [3]. Influence of the axial strain can be studied with a variety of measurement techniques.…”