1. C. J. Kovacs, M. Majoros, M. D. Sumption, E. Collings
2MOr1A Coated Conductors II: Properties Important for Applications
REBCO Roebel cable stability, current sharing, and quench measurements in a liquid helium bath and applied magnetic fields up to 10 Tesla
C. J. Kovacs, M. Majoros, M. D. Sumption, E. Collings
This work was supported by the U.S. Department of Energy, Office of Science, Division of High Energy Physics, under Grant DE-SC

2. 2MOr1A-03 - Coated Conductors II: Properties Important for Applications
Motivation
Measure:
MQE
NZP
Current Sharing
All at varying I/Ic of REBCO Roebel cables in LHe at fields up to 12 Tesla. Previous measurements by Majoros et al. at 77K demonstrated high ICR and little current sharing without the use of soldered on copper splices.
Majoros et al. “Stability, Inter-Strand Contact Resistance, and AC Losses in YBCO Roebel Cables” IEEE Trans on Appl Supercond 24, 3 (2014)

3. Probe G-10 U-shaped holder Helium cooled leads (rated for 1000A)
2MOr1A Coated Conductors II: Properties Important for Applications
Probe
G-10 U-shaped holder
Helium cooled leads (rated for 1000A)
Teflon sheet and Kapton Tape to hold sample stationary.
Designed to barely fit in 60mm bore magnet.

4. 2MOr1A-03 - Coated Conductors II: Properties Important for Applications
Probe

5. Sample 9-tape REBCO Roebel cable.
2MOr1A Coated Conductors II: Properties Important for Applications
Sample
9-tape REBCO Roebel cable.
Tapes from SuperPower, Cable from Robinson Research Institute.
Each 14mm tape ~300A at 77K (before cut).
Width off individual tapes after cut: 4.9 mm
Length of cable inbetween solder regions: 35.5 cm
Shielded from direct LHe environment with kapton/Teflon sheet wrap.

6. Instrumentation 40 voltage taps 5 Type-E thermocouples
2MOr1A Coated Conductors II: Properties Important for Applications
Instrumentation
40 voltage taps
5 Type-E thermocouples
3 40Ω Kapton heaters
Labview with:
National Instruments DAQ
Lakeshore 224 Temperature monitors
Keithley 2182A nanovoltmeters
= Voltage Tap
= Type-E Thermocouple
= Kapton Heater
= Soldered Current Tap

7. Ic Measurement at 10T and 4.2K
2MOr1A Coated Conductors II: Properties Important for Applications
Ic Measurement at 10T and 4.2K
Iq= 1140 amps
Quench protection worked and sample not damaged.
No current sharing was witnessed.
There was an baseline during current ramping (1A/s), most likely a thermovoltage.
Voltage jumps are likely due to cable transverse motion due to Lorentz forces
The cable wasn’t epoxy impregnated and at 10T and carrying 1140 A the transverse force on the cable was 140 lbs.

8. Heat Pulse Measurement
2MOr1A Coated Conductors II: Properties Important for Applications
Heat Pulse Measurement

9. Heat Pulse Measurement
2MOr1A Coated Conductors II: Properties Important for Applications
Heat Pulse Measurement
I/Ic= 0.27 (300A)
Heat pulse was 37 J total (~3.7W over 10s)
No transverse current sharing was witnessed, so:
MQE > 37 J at 10T, 4.2K, and I/Ic=0.27

10. Instrumentation Damage
2MOr1A Coated Conductors II: Properties Important for Applications
Instrumentation Damage
After the Ic measurement (which was above the recommended 1000A current lead limit) instrumentation wires were damaged due to heat.
An additional feedthrough was leaking helium gas pressure, preventing it from traveling through the He-cooled leads.

11. 2MOr1A-03 - Coated Conductors II: Properties Important for Applications
Conclusions
The Ic at 10T and 4.2K of the 9 tape Superpower REBCO Roebel cable was 1140A.
The MQE of the cable with I/Ic=0.27 and at 10T and 4.2K was greater than 37 J (assuming 100% of the energy went into the cable).