Surface NMR Coil Layout for Faster, Higher-SNR Groundwater Detection
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Solution Overview
Problem
Traditional surface nuclear magnetic resonance groundwater detection methods suffer from low signal-to-noise ratio and low detection efficiency, especially in complex noise environments, making large-scale regional surveys impractical.
Innovation Solution
A method utilizing a concentric arrangement of a direct current transmitting coil and an alternating current transmitting coil, adjusting pulse times and intervals to control magnetization intensity, enhancing signal amplitude and improving detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pre-polarization method is used to improve signal-to-noise ratio, then signal amplitude is significantly improved, but detection efficiency is reduced due to long pre-polarization pulse (4-7 seconds or more)
Solution Approach 1:
The patent applies preliminary pre-polarization action to align hydrogen atom magnetization vectors before the main detection pulse, thereby enhancing the signal amplitude and improving the signal-to-noise ratio without requiring excessively long pulse durations
Solution Approach 2:
The patent employs periodic alternating excitation pulses with optimized time intervals to repeatedly flip the magnetization vectors, allowing the system to accumulate signal while maintaining efficient detection cycles, thus improving both signal-to-noise ratio and detection efficiency
2Productivity
If steady-state pulse detection method is used to improve detection efficiency, then pulse interval is shortened and emission time is reduced, but signal-to-noise ratio is not improved
Solution Approach 1:
The patent applies preliminary pre-polarization action to align hydrogen atom magnetization vectors before the main detection pulse, thereby enhancing the signal amplitude and improving the signal-to-noise ratio without requiring excessively long pulse durations
Solution Approach 2:
The patent employs periodic alternating excitation pulses with optimized time intervals to repeatedly flip the magnetization vectors, allowing the system to accumulate signal while maintaining efficient detection cycles, thus improving both signal-to-noise ratio and detection efficiency
3Device complexity
If traditional surface nuclear magnetic resonance method is used, then geomagnetic field is utilized as background field, but signal-to-noise ratio is low and effective signal is overwhelmed by noise in strong interference environments
Solution Approach 1:
The patent changes the parameter of background magnetic field from geomagnetic field to controllable DC pre-polarization field, which provides a stronger and more stable magnetic field environment, thereby significantly improving the signal-to-noise ratio while maintaining system feasibility
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves a high signal-to-noise ratio and increased detection efficiency by stabilizing magnetization intensity within a certain range, reducing pulse emission time to under 1 second.
Implementation Method 1
calculating a direct current pre-polarization magnetic field generated by the direct current transmitting coil in an underground space
Implementation Method 2
calculating a radio frequency excitation magnetic field generated by the alternating current transmitting coil in the underground space
Implementation Method 3
uses an alternating current transmitting coil to emit radio frequency pulses to excite hydrogen atoms in groundwater to undergo magnetic resonance phenomenon
Data Source
AI summary
A high-efficiency and high signal-to-noise ratio surface nuclear magnetic resonance detection method is provided. The present disclosure adopts a concentric arrangement of a direct current transmitting coil and an alternating current transmitting coil to form a transmitting coil group, replacing the traditional single alternating current transmitting coil. Through the change of magnetization intensity caused by alternating excitation, the direct current emission time, alternating current emission time and emission interval time are adjusted, and the magnetization intensity is controlled to be gradually accumulated and stabilized in a certain range, thus improving the macro magnetization vector of hydrogen atoms. The single pulse emission time of the alternating excitation emission mode provided by the present disclosure is within 1 second, which can effectively improve the detection efficiency. The present disclosure achieves the effect of simultaneously improving the signal-to-noise ratio of surface nuclear magnetic resonance detection signals and enhancing detection efficiency.