Development of CORC® cable terminations and

low-loss joints for use in magnets for fusion

Tapering of tapes allows even current injection

CORC® conductors

Future work

Joints tested with and without tapering

Consistent contact resistance between terminations and every tape in

an HTS cable is essential to energize the cable to its full capacity

Milled MSR

powder

Demountable joints

This work was in part supported by the US

Department of Energy under agreement

numbers DE-SC0013723, DE-SC0018125,

DE-SC0014009

Conductor on Round Core (CORC®) cables

and wires consist of High Temperature

Superconducting (HTS) tapes wound

helically around a small former

CORC® magnet cables and wires are being

developed for fusion magnets with high in-field

operating currents

Jeremy Weiss and Danko van der Laan Advanced Conductor Technologies LLC, Boulder, Colorado 80301, U.S.A

CORC® tube terminals can easily be

clamped together into joints

CORC® cables or wires can be bundled

together into cable-in-conduit

conductors (CICC) rated for currents of

50-100 kA or more

CORC®

magnet cables CORC®

magnet wires

Diameter 5 to 8 mm 2.5 to 4.5 mm

Temperature, Field 4.2 K, 20 T 30 K, 8 T 4.2 K, 20 T 30 K, 8 T

Current > 10,000 A > 7,500 A > 5,000 A > 3,500 A

Current density Up to 600

A/mm2

Up to 450 A/mm2

Up to 450 A/mm2

Up to 340 A/mm2

Tim Mulder and Herman ten Kate CERN and University of Twente

Tube terminals: R (76 K) = 5 to 50 nΩ

0 1000 2000 3000 4000

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

0.0030

101 n184 n

R (at 70 % Ic)

Untapered

Single taper

Fully tapered

V(V

)I(A)

76 K

350 n

Top terminals

(lap joint with current lead)

Bottom terminals/joint

(praying hands joint)

Plug style Male to Female connectors:

R (76 K) = 465 nΩ (old data, not-tapered)

Clamped praying hands joint between tube

terminals: R (4.2 K) = 7.9 nΩ

Image courtesy

of X. Wang

Uneven current injection from terminals with untapered tapes results in higher overall

contact resistance and non-linear V(I) transitions below the critical current

Joints tested between two CORC®

cables with 30 tapes each

Thu-Mo-Po4.04-02 [25]

0 5000 10000

0.00

0.05

0.10

77K

194 n

Vo

lta

ge

(m

V)

I(A)

7.9 n

4.2K

6x1 CORC® CICC terminations and joints

CORC® bundle O.D. 22 – 24 mm

Tim Mulder’s thesis: Advancing ReBCO-CORC Wire and Cable-

In-Conduit Conductor Technology for Superconducting Magnets

https://doi.org/10.3990/1.9789036546164

6x1 CICC terminations: R (5 K) = 2 to 4 nΩ

Splice between two samples: R (5 K) = 3.3 nΩ

Two samples tested in series at

the SULTAN test facility

Terminal dimensions

Sample 1: Top terminal

Sample 1: Bottom terminal

Sample 2: Top terminal

Sample 2: Bottom terminal

Sample 1: Total

Sample 2: Total

Plug style joint with tapered cables

Plate style joints

Next generation of CORC® demountable

joints aiming at < 1 nΩ resistance at 4.2 K