Articles | Volume 14, issue 2
https://doi.org/10.5194/gi-14-139-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gi-14-139-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
A high-duty-cycle transmitter unit for steady-state surface NMR instruments
Nikhil B. Gaikwad
Department of Electrical and Computer Engineering, Aarhus University, 8200 Aarhus N, Denmark
Lichao Liu
Hydrogeophysics Group, Department of Geoscience, Aarhus University, 8000 Aarhus C, Denmark
Matthew P. Griffiths
Hydrogeophysics Group, Department of Geoscience, Aarhus University, 8000 Aarhus C, Denmark
Denys Grombacher
Hydrogeophysics Group, Department of Geoscience, Aarhus University, 8000 Aarhus C, Denmark
Department of Electrical and Computer Engineering, Aarhus University, 8200 Aarhus N, Denmark
Related authors
No articles found.
Mathias Vang, Jakob Juul Larsen, Anders Vest Christiansen, and Denys Grombacher
EGUsphere, https://doi.org/10.5194/egusphere-2025-406, https://doi.org/10.5194/egusphere-2025-406, 2025
Short summary
Short summary
To manage groundwater effectively, it's important to understand subsurface water systems. Geophysical methods can characterize subsurface layers, but relying on just one method can be misleading. This study combines two methods – Transient electromagnetics and surface nuclear magnetic resonance – in a K-means clustering scheme to better resolve freshwater and saltwater zones. Two case studies showed how a combined approach improves characterization of these hydrogeological important layers.
Smith Kashiram Khare, Paul McLachlan, Pradip Kumar Maurya, and Jakob Juul Larsen
Geosci. Instrum. Method. Data Syst., 13, 27–41, https://doi.org/10.5194/gi-13-27-2024, https://doi.org/10.5194/gi-13-27-2024, 2024
Short summary
Short summary
Data recorded with transient electromagnetics are typically gated to improve the signal-to-noise ratio. Gating corresponds to low-pass filtering of data with the shape of the gate giving the frequency response. We show that standard gate shapes can lead to significant correlation between gates caused by distortion from VLF radios. A multi-objective cost function is used to select optimum gate shapes with less influence from radio noise. Performance is demonstrated using synthetic and field data.
Mathias Vang, Denys Grombacher, Matthew P. Griffiths, Lichao Liu, and Jakob Juul Larsen
Hydrol. Earth Syst. Sci., 27, 3115–3124, https://doi.org/10.5194/hess-27-3115-2023, https://doi.org/10.5194/hess-27-3115-2023, 2023
Short summary
Short summary
In this paper, we use a novel surface nuclear magnetic resonance (SNMR) method for rapid high-quality data acquisition. The SNMR results from more than 100 soundings in three different case studies were used to map groundwater. The soundings successfully track the water table through the three areas and are compared to boreholes and other geophysical measurements. The study highlights the use of SNMR in hydrological surveys and as a tool for regional mapping of the water table.
Muhammad Rizwan Asif, Nikolaj Foged, Thue Bording, Jakob Juul Larsen, and Anders Vest Christiansen
Earth Syst. Sci. Data, 15, 1389–1401, https://doi.org/10.5194/essd-15-1389-2023, https://doi.org/10.5194/essd-15-1389-2023, 2023
Short summary
Short summary
To apply a deep learning (DL) algorithm to electromagnetic (EM) methods, subsurface resistivity models and/or the corresponding EM responses are often required. To date, there are no standardized EM datasets, which hinders the progress and evolution of DL methods due to data inconsistency. Therefore, we present a large-scale physics-driven model database of geologically plausible and EM-resolvable subsurface models to incorporate consistency and reliability into DL applications for EM methods.
Hilary A. Dugan, Peter T. Doran, Denys Grombacher, Esben Auken, Thue Bording, Nikolaj Foged, Neil Foley, Jill Mikucki, Ross A. Virginia, and Slawek Tulaczyk
The Cryosphere, 16, 4977–4983, https://doi.org/10.5194/tc-16-4977-2022, https://doi.org/10.5194/tc-16-4977-2022, 2022
Short summary
Short summary
In the McMurdo Dry Valleys of Antarctica, a deep groundwater system has been hypothesized to connect Don Juan Pond and Lake Vanda, both surface waterbodies that contain very high concentrations of salt. This is unusual, since permafrost in polar landscapes is thought to prevent subsurface hydrologic connectivity. We show results from an airborne geophysical survey that reveals widespread unfrozen brine in Wright Valley and points to the potential for deep valley-wide brine conduits.
M. Andy Kass, Esben Auken, Jakob Juul Larsen, and Anders Vest Christiansen
Geosci. Instrum. Method. Data Syst., 10, 313–323, https://doi.org/10.5194/gi-10-313-2021, https://doi.org/10.5194/gi-10-313-2021, 2021
Short summary
Short summary
We have developed a towed magnetic gradiometer system for rapid acquisition of magnetic and magnetic gradient maps. This high-resolution system is flexible and has applications to utility detection, archaeology, unexploded ordnance, or any other applications where high-resolution maps of the magnetic field or gradient are required. Processing of the data has been simplified as much as possible to facilitate rapid results and interpretations.
Krista F. Myers, Peter T. Doran, Slawek M. Tulaczyk, Neil T. Foley, Thue S. Bording, Esben Auken, Hilary A. Dugan, Jill A. Mikucki, Nikolaj Foged, Denys Grombacher, and Ross A. Virginia
The Cryosphere, 15, 3577–3593, https://doi.org/10.5194/tc-15-3577-2021, https://doi.org/10.5194/tc-15-3577-2021, 2021
Short summary
Short summary
Lake Fryxell, Antarctica, has undergone hundreds of meters of change in recent geologic history. However, there is disagreement on when lake levels were higher and by how much. This study uses resistivity data to map the subsurface conditions (frozen versus unfrozen ground) to map ancient shorelines. Our models indicate that Lake Fryxell was up to 60 m higher just 1500 to 4000 years ago. This amount of lake level change shows how sensitive these systems are to small changes in temperature.
Jakob Juul Larsen, Stine Søgaard Pedersen, Nikolaj Foged, and Esben Auken
Geosci. Instrum. Method. Data Syst., 10, 81–90, https://doi.org/10.5194/gi-10-81-2021, https://doi.org/10.5194/gi-10-81-2021, 2021
Short summary
Short summary
The transient electromagnetic method (TEM) is widely used for mapping subsurface resistivity structures, but data are inevitably contaminated by noise from various sources including radio signals in the very low frequency (VLF) 3–30 kHz band. We present an approach where VLF noise is effectively suppressed with a new post-processing scheme where boxcar gates are combined into semi-tapered gates. The result is a 20 % increase in the depth of investigation for the presented test survey.
Cited articles
Beauchamp, R. M., Arumugam, D. D., Burgin, M. S., Bush, J. D., Khazendar, A., Gim, Y., Almorqi, S., Almalki, M., Almutairi, Y. A., Alsama, A. A., and Alanezi, A. G.: Can Airborne Ground Penetrating Radars Explore Groundwater in Hyper-Arid Regions?, IEEE Access, 6, 27736–27759, https://doi.org/10.1109/ACCESS.2018.2840038, 2018. a
Behroozmand, A. A., Keating, K., and Auken, E.: A review of the principles and applications of the NMR technique for near-surface characterization, Surv. Geophys., 36, 27–85, https://doi.org/10.1007/s10712-014-9304-0, 2015. a, b, c
Binley, A., Hubbard, S. S., Huisman, J. A., Revil, A., Robinson, D. A., Singha, K., and Slater, L. D.: The emergence of hydrogeophysics for improved understanding of subsurface processes over multiple scales, Water Resour. Res., 51, 3837–3866, https://doi.org/10.1002/2014WR015282, 2015. a
Carr, H. Y.: Steady-state free precession in nuclear magnetic resonance, Phys. Rev., 112, 1693–1701, https://doi.org/10.1103/PhysRev.112.1693, 1958. a
Chen, H., Yang, J., and Xu, S.: Electrothermal-Based Junction Temperature Estimation Model for Converter of Switched Reluctance Motor Drive System, IEEE T. Ind. Electron., 67, 874–883, https://doi.org/10.1109/TIE.2019.2898600, 2020. a
Costabel, S.: Noise analysis and cancellation for the underground application of magnetic resonance using a multi-component reference antenna – Case study from the rock laboratory of Mont Terri, Switzerland, J. Appl. Geophys., 169, 85–97, https://doi.org/10.1016/j.jappgeo.2019.06.019, 2019. a
Du, G., Lin, J., Zhang, J., Yi, X., and Jiang, C.: Study on Shortening the Dead Time of Surface Nuclear Magnetic Resonance Instrument Using Bipolar Phase Pulses, IEEE T. Instrum. Meas., 69, 1268–1274, https://doi.org/10.1109/TIM.2019.2911755, 2020. a
Famiglietti, J. S.: The global groundwater crisis, Nat. Clim. Change, 4, 945–948, https://doi.org/10.1038/nclimate2425, 2014. a
Girard, J.-F., Jodry, C., and Matthey, P.: On-site characterization of the spatio-temporal structure of the noise for MRS measurements using a pair of eight-shape loops, J. Appl. Geophys., 178, 104075, https://doi.org/10.1016/j.jappgeo.2020.104075, 2020. a
Griffiths, M. P., Grombacher, D., and Larsen, J. J.: Efficient numerical Bloch solutions for multipulse surface NMR, Geophys. J. Int., 227, 1905–1916, https://doi.org/10.1093/gji/ggab321, 2021. a, b
Griffiths, M. P., Grombacher, D. J., Liu, L., Vang, M., and Larsen, J. J.: Forward modelling steady-state free-precession insurface NMR, IEEE T. Geosci. Remote, 60, 4513510, https://doi.org/10.1109/TGRS.2022.3221624, 2022. a
Grombacher, D., Liu, L., Griffiths, M. P., Vang, M. Ø., and Larsen, J. J.: Steady-state surface NMR for mapping of groundwater, Geophys. Res. Lett., 48, e2021GL095381, https://doi.org/10.1029/2021GL095381, 2021. a
Grombacher, D., Griffiths, M. P., Liu, L., Vang, M. Ø., and Larsen, J. J.: Frequency Shifting Steady-State Surface NMR Signals to Avoid Problematic Narrowband-Noise Sources, Geophys. Res. Lett., 49, e2021GL097402, https://doi.org/10.1029/2021GL097402, 2022. a, b
Grunewald, E., Grombacher, D., and Walsh, D.: Adiabatic pulses enhance surface nuclear magnetic resonance measurement and survey speed for groundwater investigations, Geophysics, 81, WB85–WB96, https://doi.org/10.1190/geo2015-0527.1, 2016. a
Hiller, T., Costabel, S., Radic, T., Dlugosch, R., and Müller-Petke, M.: Feasibility study on prepolarized surface nuclear magnetic resonance for soil moisture measurements, Vadose Zone J., 20, e20138, https://doi.org/10.1002/vzj2.20138, 2021. a
Infineon Technologies AG: AN2015-10 Transient Thermal Measurements and thermal equivalent circuit models (V1.2), Infineon Technologies AG, 2020-04-14, https://www.infineon.com/dgdl/Infineon-Thermal_equivalent_circuit_models-ApplicationNotes-v01_02-EN.pdf?fileId=db3a30431a5c32f2011aa65358394dd2 (last access: 2 July 2025) 2020. a
Jiang, C., Zhou, Y., Wang, Y., Duan, Q., and Tian, B.: Harmonic Noise-Elimination Method Based on the Synchroextracting Transform for Magnetic-Resonance Sounding Data, IEEE T. Instrum. Meas., 70, 1–11, https://doi.org/10.1109/TIM.2021.3102689, 2021. a
Kremer, T., Irons, T., Müller-Petke, M., and Larsen, J. J.: Review of Acquisition and Signal Processing Methods for Electromagnetic Noise Reduction and Retrieval of Surface Nuclear Magnetic Resonance Parameters, Surv. Geophys., 43, 999–1053, https://doi.org/10.1007/s10712-022-09695-3, 2022. a
Larsen, J. J., Liu, L., Grombacher, D., Osterman, G., and Auken, E.: Apsu – A New Compact Surface Nuclear Magnetic Resonance System for Groundwater Investigation, GEOPHYSICS, 85, JM1–JM11, https://doi.org/10.1190/geo2018-0779.1, 2020. a, b, c, d
Legchenko, A. and Pierrat, G.: Glimpse into the design of MRS instrument, Near Surf. Geophys., 12, 297–308, https://doi.org/10.3997/1873-0604.2014006, 2014. a
Legchenko, A., Baltassat, J.-M., Beauce, A., and Bernard, J.: Nuclear magnetic resonance as a geophysical tool for hydrogeologist, J. Appl. Geophys., 50, 21–46, https://doi.org/10.1016/S0926-9851(02)00128-3, 2002. a
Li, T., Feng, L.-B., Duan, Q.-M., Lin, J., Yi, X.-F., Jiang, C.-D., and Li, S.-Y.: Research and Realization of Short Dead-Time Surface Nuclear Magnetic Resonance for Groundwater Exploration, IEEE T. Instrum. Meas., 64, 278–287, https://doi.org/10.1109/TIM.2014.2338693, 2015. a
Lin, T., Li, S., Gao, X., and Zhang, Y.: Improved technology using transmitting currents with short shutdown times for surface nuclear magnetic resonance, Rev. Sci. Instrum., 91, 084501, https://doi.org/10.1063/5.0007848, 2020. a
Lin, T., Zhou, K., Chen, C., and Zhang, Y.: An Improved Air-Core Coil Sensor With a Fast Switch and Differential Structure for Prepolarization Surface Nuclear Magnetic Resonance, IEEE T. Instrum. Meas., 70, 1–10, https://doi.org/10.1109/TIM.2021.3109736, 2021. a, b
Liu, J., Yang, H., Gosling, S. N., Kummu, M., Flörke, M., Pfister, S., Hanasaki, N., Wada, Y., Zhang, X., Zheng, C., Alcomo, J., and Oki, T.: Water scarcity assessments in the past, presents, and the future, Earths Future, 5, 545–559, https://doi.org/10.1002/2016EF000518, 2017. a
Liu, L., Grombacher, D., Auken, E., and Larsen, J. J.: Apsu: a wireless multichannel receiver system for surface nuclear magnetic resonance groundwater investigations, Geosci. Instrum. Method. Data Syst., 8, 1–11, https://doi.org/10.5194/gi-8-1-2019, 2019. a, b
Postel, S. L.: Entering an era of water scarcity: the challenges ahead, Ecol. Appl., 10, 941–948, https://doi.org/10.1890/1051-0761(2000)010[0941:EAEOWS]2.0.CO;2, 2000. a
Radic, T.: Improving the Signal-to-Noise Ratio of Surface NMR Data Due to the Remote Reference Technique, in: Near Surface 2006 – 12th EAGE European Meeting of Environmental and Engineering Geophysics, 4–6 September 2006, Helsinki, Finland, https://doi.org/10.3997/2214-4609.201402690, 2006. a, b
Siemon, B., Christiansen, A. V., and Auken, E.: A review of helicopter-borne electromagnetic methods for groundwater exploration, Near Surf. Geophys., 7, 629–646, https://doi.org/10.3997/1873-0604.2009043, 2009. a
Walsh, D. O.: Multi-Channel Surface NMR Instrumentation and Software for 1D/2D Groundwater Investigations, J. Appl. Geophys., 66, 140–150, https://doi.org/10.1016/j.jappgeo.2008.03.006, 2008. a, b
Walsh, D. O., Grunewald, E. D., Turner, P., Hinnell, A., and Ferre, T. P. A.: Surface NMR Instrumentation and methods for detecting and characterizing water in the vadose zone, Near Surf. Geophys., 12, 271–284, https://doi.org/10.3997/1873-0604.2013066, 2014. a
Wang, P., Zhu, J., Wang, H., and Lin, T.: An On-Site Harmonic Noise Cancellation Antenna With a Multinode Loop for Magnetic Resonance Sounding Measurement, IEEE T. Instrum. Meas., 71, 1–10, https://doi.org/10.1109/TIM.2022.3169796, 2022. a
Wu, X., Xue, G., Fang, G., Li, X., and Ji, Y.: The Development and Applications of the Semi-Airborne Electromagnetic System in China, IEEE Access, 7, 104956–104966, https://doi.org/10.1109/ACCESS.2019.2930961, 2019. a, b
Yi, X., Zhang, J., Tian, B., and Jiang, C.: Design of Magnetic Resonance Sounding Antenna and Matching Circuit for the Risk Detection of Tunnel Water-Induced Disasters, IEEE T. Instrum. Meas., 68, 4945–4953, https://doi.org/10.1109/TIM.2019.2896372, 2019. a
Zhu, J., Yang, Y., Teng, F., and Lin, T.: Dynamic duty cycle control strategy for surface nuclear magnetic resonance sounding system, Rev. Sci. Instrum., 90, 035109, https://doi.org/10.1063/1.5078764, 2019. a
Short summary
This work presents simulations, modelling, and experimental verification of a novel steady-state surface nuclear magnetic resonance (NMR) transmitter used for the non-invasive exploration of groundwater. The paper focuses on three main aspects of high-current transmitter instrumentation: thermal management, current-drooping, and pulse stability. This work will interest readers involved in geoscientific instrument prototyping for groundwater exploration using portable geoscientific instruments.
This work presents simulations, modelling, and experimental verification of a novel steady-state...