Single-Strand Excitation for Probing Current Sharing and Parallel Resistance in Cored Nb3Sn Rutherford Cables at 4.2 K and 10 Tesla
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Date
2017
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Publisher
IEEE
Abstract
A rig was fabricated to test single-strand excitation and current sharing in Nb3Sn Rutherford Cables. Measurements were performed on 400 mm lengths of a 27-strand, cored cable. In preparation for measurement, the cable was mounted onto a U-shaped holder, reacted for 72-48-50 h at 210-400-665 °C under 20 MPa. Current was injected into a single strand of the cable, and the onset of current sharing was seen above single strand Ic. After the onset of transition the I-V showed a flat baseline the slope of which gave the transfer resistance to the two neighboring strands. Two cable samples were measured, one of which was reacted in a dilute oxygen atmosphere. The slightly oxidized cable had a R// of 280 nΩ whereas the other sample had a R// was 70 nΩ per lay pitch. Varying I/Ic and a heat pulse from a carbon paste heater was used to turn off successive pairs of neighboring strands, and the resulting current-distribution was measured using voltage taps. These measurements were performed as a screening for cable and cable preparation protocol for larger scale measurements.
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Keywords
stability, Nb3Sn, LTS cables
Citation
Published version: IEEE Transactions on Applied Superconductivity (Volume: 27, Issue: 4, June 2017) Article Sequence Number: 4802204. https://doi.org/10.1109/TASC.2017.2661279