Speakers
Description
Characterization of superconducting Rare-Earth Barium Copper oxide (REBCO) tapes is a prerequisite to produce electrotechnical devices such as electromagnets, superconducting fault current limiters or superconducting magnetic energy storage.
The Grenoble applied superconductivity group is developing a high field large bore cryocooled magnet and knowing the critical current Ic everywhere in the device is essential for the realization and operation of the magnet. Therefore, a transport current characterization activity for commercial tape is under development. The chosen approach is the pulsed current method coupled with the use of microbridges. The greatest advantage of the pulsed current method over the ramp method is that, for sufficiently short pulses in the order of the millisecond, the temperature drift of the sample can be neglected [1], and the behavior at high dissipation levels can be observed safely. On the other hand, other phenomena such as magnetic relaxation and the noise of a high-speed acquisition system must be considered to obtain consistent results. The use of microbridge is chosen to reduce the amount of current to be injected through the characterization probe.
A characterization probe was designed and assembled to fit into a 19T superconducting magnet available at the high field facility LNCMI with a variable temperature insert. This probe can carry upward of 200 A between 4.2 K and 77 K, supports a rotating sample holder for Ic-θ measurements and has superconducting current leads to reduce heat dissipation in the cryogenic environment.
Measurement of the V-I characteristic of REBCO tape samples using both pulsed current and ramp method combined with the use of current sharing algorithms, enables us to estimate not only the critical current Ic but the E(J) relationship over a wide range of Electrical field.
Reference
[1] Y. Tsuchiya et al., IEEE Trans. Appl. Supercond. 34, 9500207 (2024).
