Dendritic flux avalanches in a superconducting MgB2 tape

TL;DR

This study investigates thermomagnetic avalanches in MgB2 superconducting tapes, revealing their structure, thresholds, and dependence on magnetic field, which is crucial for improving their operational stability.

Contribution

The paper provides the first detailed visualization and analysis of dendritic flux avalanches in MgB2 tapes, combining magneto-optical imaging with magnetic measurements.

Findings

Avalanches occur between 1.7 mT and 2.5 T magnetic fields.

Small avalanches are edge intrusions, undetectable in magnetic moment measurements.

Larger avalanches exhibit dendritic structures.

Abstract

MgB2 tapes with high critical current have a significant technological potential, but can experience operational breakdown due to thermomagnetic instability. Using magneto-optical imaging the spatial structure of the thermomagnetic avalanches has been resolved, and the reproducibility and thresholds for their appearance have been determined. By combining magneto-optical imaging with magnetic moment measurements, it is found that avalanches appear in a range between 1.7 mT and 2.5 T. Avalanches appearing at low fields are small intrusions at the tape's edge and non-detectable in measurements of magnetic moment. Larger avalanches have dendritic structures.