Magnetic field stability of superconducting magnets using external power supplies for NMR/MRI

The magnetic field stability of superconducting magnets powered by external power supplies has been investigated. The magnetic field fluctuation caused by current fluctuation generated in the external power supply is classified according to its frequency and range. Superconducting magnets for high-resolution NMR (Nuclear Magnetic Resonance) require one of the highest stability in the variety of application. It is demonstrated that high temperature superconducting magnets in driven mode can be applicable for high-resolution NMR. Such kind of technology will also be used for the future field swept NMR of quadrupolar nuclei which is now being developed. (author)