High-sensitivity cooled coil system for nuclear magnetic resonance in kHz range
- College of Instrumentation and Electrical Engineering, Jilin University, Changchun 130061 (China)
- Peter Grünberg Institute (PGI-8), Forschungszentrum Jülich (FZJ), D-52425 Jülich (Germany)
In several low-field Nuclear Magnetic Resonance (LF-NMR) and surface nuclear magnetic resonance applications, i.e., in the frequency range of kHz, high sensitivity magnetic field detectors are needed. Usually, low-T{sub c} superconducting quantum interference devices (SQUIDs) with a high field sensitivity of about 1 fT/Hz{sup 1/2} are employed as detectors. Considering the flux trapping and operational difficulties associated with low-T{sub c} SQUIDs, we designed and fabricated liquid-nitrogen-cooled Cu coils for NMR detection in the kHz range. A cooled coil system consisting of a 9-cm diameter Cu coil and a low noise preamplifier was systematically investigated and reached a sensitivity of 2 fT/Hz{sup 1/2} at 77 K, which is 3 times better compared to the sensitivity at 300 K. A Q-switch circuit as an essential element for damping the ringing effects of the pickup coil was developed to acquire free induction decay signals of a water sample with minimum loss of signal. Our studies demonstrate that cooled Cu coils, if designed properly, can provide a comparable sensitivity to low-T{sub c} SQUIDs.
- OSTI ID:
- 22392244
- Journal Information:
- Review of Scientific Instruments, Vol. 85, Issue 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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