Development of a React & Wind Conductor for the ITER Toroidal Field Coils

Intra wire resistance and strain affecting the transport properties of Nb3Sn strands in cable-in-conduit conductors

“…It should also be noted that the periodicity in the crack density in the TARSIS AC loss strands is about 5 mm, which corresponds well with the TFPRO2-OST1 cable featuring an ITER Option-1 cable pattern [105], [235]. The fact that the hysteresis loss in both cable-in-conduit conductor samples corresponds so well suggests that the large degradation in the current sharing temperature T cs observed during the SULTAN cyclic loading test [83] is dominated by periodic filament strain variations due to plastic deformation of the strand, rather than a significant amount of distributed filament cracks. Obviously, the solution against this degradation is to limit the degree of filament deformation connected to strand bending and inter-strand contact stress to the utmost minimum [105], [235].…”

“…Furthermore, the use of coupling loss as a measure to assess the presence of cracks in cabled conductors is not appropriate. In cables, coupling currents between the wires dominate the magnetization signal and the reduction of inter-wire coupling loss in Nb 3 Sn cable-in-conduit conductors subjected to electromagnetic loading will mask the decrease of the intra-wire coupling loss due to crack initiation [83], [175], [176]. This implies that only measurement of the hysteresis loss conducted with sufficient accuracy in the low-frequency (mHz) range can lead to a successful comparison.…”

“…For this purpose, two sections of the full-size ITER TF sample TFPRO2-OST1 were cut by spark erosion after cyclic testing in the SULTAN facility [83]. The conductor is cabled with the same internal-tin strand OST-1 as the one discussed in section 4.4.…”

“…The coupling loss in the high-field section is 36% lower than in the low-field sample. This difference can mainly be attributed by an increase of the inter-strand resistance due to strand disengagement during cyclic loading [83], [175], [176], [233].…”

Magnetic Testing of a Superferric Dipole That Uses Metal-Oxide Insulated CICC

“…The current density in the conductor bundle is about 1 . For comparison, the current density in the ITER Toroidal Field Coils conductor bundle is 425 [5]. The strand short sample versus magnetic field and the conductor magnetic field is shown in Fig.…”