Development of Split-Type RF Coil Using High-Temperature Superconductor for NMR

We developed a split-type radio frequency (RF) coil using a high-temperature superconductor (HTS) for nuclear magnetic resonance (NMR). The coil does not have HTS thin film on substrates in the area closest to the cylindrical sample. Thus, the coil suppressed the distortion of the static magnetic field. The decreasing quality factor of the coil when a sample was loaded was suppressed because the electric-field-concentration area was placed far from the sample. The measured quality factor of the coil cooled to 11 K was 20 times higher than that of the cooled copper RF coil when D₂O was loaded. The measured maximum distortion of the static magnetic field when the split-type HTS coil was implemented was suppressed to about 37% of that when the conventional HTS coil was implemented.