Airborne Detection of Perfect Conductors: Project Gemini
Macnae, J. [1], Smiarowski, A. [2]
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1. School of Applied Sciences, RMIT University
2. Dept. of Physics, University of Toronto
ABSTRACT
High-grade nickel and copper sulphides appear as ‘perfect conductors’ to most electromagnetic and airborne electromagnetic
systems, since they have bulk electrical conductivities of the order of 100,000 S/m. Their EM response is essentially undetectable with
off-time measurements or when using non-rigid towed-bird systems. Compact AEM systems with accurate primary field bucking and
on-time or in-phase measurements are sensitive to perfect conductors, but are incapable of detecting deep targets. Calculations in
2004 suggested that it should be easy for AEM to detect ‘perfect conductors’ using GPS systems to define geometry, provided the
receiver was several hundred metres distant from the transmitter. A twin (Gemini) aircraft test was undertaken to test this concept in
2005. The field test was completely successful. Geometric and signal noise levels in the test were much better than 0.5% of the
primary field at 400 m separation, allowing detection and characterisation of the 30Hz, in-phase response of both small and extended
‘perfect conductors’ It is predicted that a 200 m by 100 m perfect conductor target should be detectable to depths of 200 m below
surface using off-the-shelf technology
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