Full Tensor SQUID Gradiometer for airborne exploration

SummaryIPHT Jena and Supracon AG develop and fabricate full tensor magnetic gradiometer (FTMG) systems, based on low-temperature-superconducting (LTS) planar-type SQUID (Superconducting Quantum Interference Device) gradiometers of first order. The systems are operated by Spectrem Air Ltd., jointly owned by Anglo American and De Beers. This paper describes details of the system setup, data processing and achieved performance parameters.The sensors work at 4.2 K in liquid helium. With a base length of only 3.5 cm a real gradient measurement is possible. With six gradiometer the full magnetic gradient tensor can be measured with redundancy, allowing for high system reliability and the application of enhanced noise reduction techniques.The data of the FTMG system will allow for a 3D inversion for the underlying magnetic sources. Examples of 2D maps of tensor components with high spatial resolution are shown.