Electromagnetic Evaluation of HTS RF Coils for Nuclear Magnetic Resonance
T. Yamada, A. Saito, S. Oikawa, K. Koshita, M. Takahashi, H. Maeda, S. Ohshima
IEEE Transactions on Applied Superconductivity
Volume: 25 Issue: 3
NMR RF coil, quality factor, high temperature superconductors, two frequency, in-phase mode, out-phase mode
We propose a Helmholtz-type probe coil that uses a high-temperature superconductor (HTS) for use as 700-MHz NMR RF coils with a high unloaded quality factor (Qu). We analyzed the microwave resonant properties of a one-turn coil set face-to-face. The coils were made of a YBa2Cu3O7-d (YBCO) film deposited on an r-plane sapphire substrate. The film thickness was 300 nm. The resonant frequency was found to split into an in-phase (lower frequency) and out-phase (higher frequency) modes. We focused on the self-resonant frequency of the one-turn coil. We simulated the horizontal magnetic field caused by the RF coil. Although the coil could generate a sufficiently large transverse magnetic field in the in-phase mode, such a large field could not be generated in the out-phase mode. Therefore, we decided to use the in-phase mode. We also measured and simulated Qu to confirm that it was large enough for use in the 700-MHz NMR system.
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