Simulation of Magnetic Resonance Sounding With a Delayed Adiabatic Pulse

Abstract

Magnetic resonance sounding (MRS) is used to identify groundwater by exciting and measuring the nuclear magnetic resonance of hydrogen nuclei in subsurface aquifers. However, the MRS response is particularly weak and has a low signal-to-noise ratio (SNR); therefore, signal enhancement methods, such as adiabatic pulses, are essential for MRS applications with strong interference. The key challenges of utilizing this novel method are to increase the MRS signal response and sensitivity for field measurements. In this letter, we report an improved transmitting mode of a commonly used adiabatic half-passage (AHP) pulse by combining this pulse with an earlier fixed frequency off-resonant pulse of short duration, thereby increasing the theoretical MRS sensitivity. Simulation results demonstrate that the novel approach could be used to further improve the signal responses, i.e., in terms of the SNR and potential resolution, for MRS exploration of high-noise environments.