Apsu - A compact surface NMR instrument for groundwater investigations

Jakob Juul Larsen*, Matthew Griffiths, Mathias Vang, Lichao Liu, Denys Grombacher

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperConference articleResearchpeer-review


We have recently developed a new surface nuclear magnetic resonance (NMR) instrument, named Apsu. The instrument is designed with low weight and flexibility in mind. Our design differs from the commercial surface NMR instruments in several aspects. In particular, the instrument is based on an un-tuned transmitter coil, the NMR pulses are independently controlled at the half-cycle level and the instrument is powered from a generator. The modular instrument uses a 50 m x 50 m coil to transmit the NMR excitation pulse and receives the NMR signal in one or several small 9 m x 9 m receiver coils. Recently, the instrument has been updated to operate in coincident coil mode, so the transmitter coil can also be used to receive the NMR signal. For remote reference noise cancellation, the instrument can connect to multiple receiver units through WiFi. The effective peak current of the system is 105 A at a Larmor frequency of 2 kHz, which corresponds to approximately 30 m depth of investigation. We give an overview of the instrument and provide a field example from Kompedal Forest, Denmark.

Original languageEnglish
JournalSEG Technical Program Expanded Abstracts
Pages (from-to)3135-3139
Number of pages5
Publication statusPublished - 2021
Event1st International Meeting for Applied Geoscience and Energy - Denver, United States
Duration: 26 Sept 20211 Oct 2021


Conference1st International Meeting for Applied Geoscience and Energy
Country/TerritoryUnited States


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