Reel-to-Reel Scanning Hall Probe Microscope Measurement on REBCO Tapes

In the past two years, a reel-to-reel (R2R) scanning hall probe microscope (SHPM) measurement system has been developed and routinely used at the University of Houston for continuous and 100% testing of REBCO-coated conductors. The background magnetic field interference has been eliminated by introducing FFT into the current density calculation. The noise has been reduced by a factor of 5 after customizing the motor driver. Moreover, since the data acquisition module has been upgraded to 100 kSPS sampling rate, the resolution has reached 0.06 mm² under the measurement configuration of 8 scans per second with scanning range of 18 mm and tape motion speed of 10 mm/s. Such resolution is likely the best reported by any group at such testing speed. It has enabled our R2R measurement system to obtain detailed current density map of narrow wires and striated multifilament tapes. With the features, the R2R SHPM is turning out to be very valuable metrology and quality assurance tool for long REBCO-coated conductors.