Overhauser Geomagnetic Sensor Based on the Dynamic Nuclear Polarization Effect for Magnetic Prospecting

Area of Science:

• Geophysics
• Physics
• Sensor Technology

Background:

• Overhauser magnetometers offer sensitive magnetic field measurements.
• Enhancing proton polarization is key to improving signal amplitude and sensor performance.
• Electromagnetic interference and resonant circuit quality factor are critical challenges.

Purpose of the Study:

• To present an alternative Overhauser geomagnetic sensor design utilizing dynamic nuclear polarization (DNP).
• To enhance proton polarization and the free induction decay (FID) signal amplitude.
• To address electromagnetic interference and improve resonant circuit performance.

Main Methods:

• Implementing dynamic nuclear polarization (DNP) for enhanced proton polarization.
• Utilizing a short-pulse method to generate the free induction decay (FID) signal.
• Designing anti-interference pick-up coils and a capacitive-loaded coaxial cavity for RF polarization.
• Developing a specialized instrument for simultaneous testing of classical proton precession and Overhauser sensors.

Main Results:

• The DNP effect significantly improves the amplitude and quality of the FID signal.
• Achieved magnetic sensitivity of 10 pT/Hz^1/2 @1 Hz.
• Demonstrated a resolution of 0.0023 nT and a measurement range of 20-100 μT.
• The capacitive-loaded coaxial cavity improved the resonant circuit's quality factor.

Conclusions:

• The proposed DNP-enhanced Overhauser geomagnetic sensor design effectively improves signal quality and sensitivity.
• The anti-interference measures and improved RF polarization method enhance sensor robustness and performance.
• The sensor achieves high sensitivity and resolution suitable for geomagnetic applications.