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A field tracking digital NMR magnetometer for in situ use with superconducting solenoids

1976; IOP Publishing; Volume: 9; Issue: 4 Linguagem: Inglês

10.1088/0022-3735/9/4/013

2051-5685

J.K. Hulbert,

Atomic and Subatomic Physics Research

A digital NMR magnetometer is described. It is designed to track changing magnetic fields over a wide range, and is suitable for use at low temperatures with high field superconducting solenoids. The instrument is not of the marginal oscillator type but is based on a small non-resonant sample coil (total volume 40 mm3) and all the RF components are wideband. The circuit uses frequency modulation to avoid disturbing the field and detects on second harmonic. The use of linear integral and second integral feedback for the holding circuit has resulted in a system which is very reliable. Using a copper resonance the circuit can reliably track fields changing at 7 mT s-1 with an absolute accuracy of 1 mT while greater accuracy is achieved at lower rates.