Ultra-Low Field SQUID-NMR using LN2 Cooled Cu Polarizing Field coil

29th International Symposium on Superconductivity

Demachi, K.^1 ; Kawagoe, S.^1 ; Ariyoshi, S.^1 ; Tanaka, S.^1

Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi

441-8580, Japan^1

关键词: Environmental magnetic fields;    Flux transformers;    Magnetically shielded room;    Measurement field;    Measurement system;    Polarizing fields;    T1 relaxation time;    Ultra-low field magnetic resonance imaging (mri) (ULF);   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/871/1/012076/pdf
DOI  :  10.1088/1742-6596/871/1/012076

来源: IOP

【 摘 要 】

We are developing an Ultra-Low Field (ULF) Magnetic Resonance Imaging (MRI) system using a High-Temperature Superconductor superconducting quantum interference device (HTS rf-SQUID) for food inspection. The advantages of the ULF-NMR (Nuclear Magnetic Resonance) / MRI as compared with a conventional high field MRI are that they are compact and of low cost. In this study, we developed a ULF SQUID-NMR system using a polarizing coil to measure fat of which relaxation time T1is shorter. The handmade polarizing coil was cooled by liquid nitrogen to reduce the resistance and accordingly increase the allowable current. The measured decay time of the polarizing field was 40 ms. The measurement system consisted of the liquid nitrogen cooled polarizing coil, a SQUID, a Cu wound flux transformer, a measurement field coil for the field of 47 μT, and an AC pulse coil for a 90°pulse field. The NMR measurements were performed in a magnetically shielded room to reduce the environmental magnetic field. The size of the sample was φ35 mm × L80 mm. After applying a polarizing field and a 90°pulse, an NMR signal was detected by the SQUID through the flux transformer. As a result, the NMR spectra of fat samples were obtained at 2.0 kHz corresponding to the measurement field Bmof 47 μT. The T1relaxation time of the mineral oil measured in Bmwas 45 ms. These results suggested that the ULF-NMR/MRI system has potential for food inspection.