Reel-to-reel Characterization towards Feedback Control in Manufacturing Long REBCO High-Temperature Superconducting Tapes

The thriving trend of large-scale, high-magnetic-field superconducting applications increases the demand for high-volume of uniform and high-performance REBCO tapes. This dissertation focuses on off-line and in-line characterization techniques for assessing the quality of long REBCO tapes. A reel-to-reel magnetization measurement method has been implemented for profiling the off-line critical current density of High-Temperature Superconducting (HTS) tapes. A cross-comparison on sensitivities via principle analysis and simulations incorporating various types of magnetization methods reveals that a combination of self-field remnant field measurement under dipole and quadrupole external magnetic field and in-field screening current field measurement is required to describe the tape performance for high-field applications and to identify the cracks and weak points. A variety of in-line monitoring techniques have been evaluated for assessment of REBCO tape quality. 2D-X-ray Diffraction (XRD) has been utilized to meet the specifications for reel-to-reel in-line measurement of REBCO tapes during manufacturing. The crystallography information is extracted from the tapes after necessary corrections and further post-processing of the acquired 2D-XRD diffraction data. Finally, the relationship between off-line and in-line characterization techniques has been investigated. Machine-learning models are trained to predict the self-field and in-field critical current based on the in-line measurement data. Also, a preliminary investigation of the relationship between process parameters and critical current has been conducted. It is anticipated that a combination of various characterization techniques will serve as a reliable feedback source for real-time quality control in a scaled-up Advanced Metal-Organic Chemical Vapor Deposition process, thereby providing longer and more uniform high-performance REBCO tapes for large-scale, high-field superconducting applications.