1887

Abstract

Summary

The Magnetic Resonance Sounding (MRS) Method allows for the direct quantification and characterization of non or weakly bounded water in near surface soil. MRS measurements in densely populated areas, like almost everywhere in central Europe, frequently cause S/R ratios of less than 1. This is why last year we have added a transmitter for the pre-polarization (PP) of the soil to our MRS apparatus MRS-MIDI-III. A field of 500 □T can be generated for several seconds within the 2 metre PP-Loop. In doing so, the nuclear magnetisation of the water within the upper 1–2 metres increases up to one magnitude. The directly following “conventional” MRS measurement then stimulates an up to 10 times greater response signal (FID). Recently we have added a further innovation to our instrument: an adiabatic pulse (AP). A Tx pulse to deviate the protons in the soil is normally constant in regards to frequency and amplitude. The specific characteristic of adiabatic pulses is that the frequency and/or current change during the pulse. Through this, the distribution of the sensitivity in the soil can be advantageously influenced and the signal amplitude increases by a factor of up to 3.

Loading

Article metrics loading...

/content/papers/10.3997/2214-4609.201802650
2018-09-09
2024-03-28
Loading full text...

Full text loading...

References

  1. De Pasquale, G. and Mohnke, O.
    [2014] Numerical Study of Pre-Polarized Surface Nuclear Magnetic Resonance in the Vadose Zone. Vadose Zone Journal, 2014, doi:10.2136/vzj2014.06.0069.
    https://doi.org/10.2136/vzj2014.06.0069 [Google Scholar]
  2. Grunwald, E., Grombacher, D. and Walsh, D.
    [2016] Adiabatic pulses enhance surface nuclear magnetic resonance measurements and survey speed for groundwater investigations. Geophysics, Vol. 81, No. 4., P85–96.
    [Google Scholar]
  3. Radic, T. and Lehmann-Horn, J.
    [2011] First field tests of a new multi-channel SNMR measuring concept. 24th European Meeting of Environmental and Engineering Geophysics, Leicester, UK.
    [Google Scholar]
  4. Radic, T. and Costabel, S.
    [2017] Steigerung des Signal zu Rausch Verhältnisses bei Feld-NMR (SNMR, MRS) Messungen mittels Vorpolarisation 77. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, Poster, 27.-30.3.2017, Potsdam.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609.201802650
Loading
/content/papers/10.3997/2214-4609.201802650
Loading

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error