A recent study published in Scientific Reports has shed light on the challenges faced by high-field nuclear magnetic resonance (NMR) magnets that utilize rare earth barium copper oxide (REBCO) coated conductors. Lead author Jeseok Bang from the Department of Electrical and Computer Engineering at Seoul National University highlights significant issues regarding field uniformity that arise during the operational phase of these magnets.
REBCO materials have emerged as a promising option for high-field magnets due to their exceptional current-carrying capacity and durability under stress. However, the research reveals that after constructing and charging a 9.4 T REBCO NMR magnet, discrepancies between the designed and measured magnetic field uniformity were observed, resulting in what are termed harmonic errors. These errors can critically impact the performance of NMR systems, which are vital in various applications, including medical imaging and materials research.
The study focused on a 400 MHz NMR magnet development project, where the magnet was subjected to multiple overcharge-discharge cycles as part of its operational protocol. A field mapping device was used to assess the magnetic fields at specific locations within the magnet’s bore, revealing a significant field uniformity difference of over 100 parts per million (ppm) between the intended and actual values.
Bang and his team developed a simulation model to better understand the causes of these discrepancies, identifying screening currents and inconsistent conductor thickness as primary factors contributing to the harmonic errors. “Even and odd-order harmonics are mainly attributed to screening current and geometric inconsistency,” Bang stated, emphasizing the importance of addressing these issues for future designs.
This research has important commercial implications. With the ability to achieve higher field uniformity, industries relying on NMR technology, such as pharmaceuticals and materials science, could see enhanced performance and accuracy in their applications. The findings suggest that while the goal of achieving sub-ppm level field uniformity may be challenging with current designs, there is a clear opportunity for innovation in the development of REBCO NMR magnets.
As the demand for advanced NMR systems grows, addressing these technical challenges could lead to significant advancements in the field, opening doors for improved research capabilities and commercial applications. The insights from Bang’s study offer a pathway for researchers and engineers to refine the design and manufacturing processes of high-field magnets, ultimately benefiting various sectors that depend on precise magnetic field applications.
