21-25 July 2019
Connecticut Convention Center, Level 6
US/Eastern timezone

M2Po2D-02 [44]: Experimental studies on the contact resistance and current sharing of superconducting CORC cables

23 Jul 2019, 13:30
2h
Level 6, Cryo Expo Exhibit Hall ()

Level 6, Cryo Expo Exhibit Hall

Speaker

Virginia Phifer

Description

$RE-Ba_2Cu_3O_{7−δ}$ (REBCO, RE = rare earth) coated conductors maintain high current densities in the presence of large magnetic fields, making REBCO a promising conductor for use in high magnetic field applications. Unfortunately, the manufacturing process produces defects, resulting in significant drops in the critical current, $I_c$, along the length of the conductor. Additional variations in $I_c$ can occur due to the anisotropic behavior of REBCO with respect to magnetic field orientation, which can reduce $I_c$ by a factor of 2 depending on field orientation at 77 K. Conductor on Round Core (CORC) cables contain multiple layers of helically wound REBCO tapes, producing a flexible, isotropic conductor that promotes current sharing between layers. This could allow current to bypass local drops in I_c and minimize the risk of hot spot formation. The current sharing capability of CORC cables depends on the tape-to-tape contact resistance, $R_c$, which can be quite large since the tapes in CORC cables are not generally soldered in order promote cable flexibility. Measurements were conducted on several CORC cables to achieve a better understanding of how different winding parameters, cable bending, and magnetic field affect $R_c$. We found that $R_c$ can take on values from 10 to over 1,000 $\mu\Omega\cdot cm^2$, resulting in a broad range of current transfer length between layers. Further experiments isolated 1 or 2 tapes with a significant drop in $I_c$ for detailed studies, from which the effects of current transfer were evident on the current-voltage transition data. We compare cables that permit current transfer around these $I_c$ drops to cables with insulation between tape layers, disabling current sharing, allowing us to clearly see the impact of current sharing on cable $I_c$.

Primary author

Co-authors

Danko van der Laan (Advanced Conductor Technologies) Drew Hazelton (SuperPower Inc.) Dr Jan Jaroszynski (Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University) Jeremy Weiss (Advanced Conductor Technologies) Lance Cooley (Fermilab) Sastry Pamidi (The Florida State University)

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