Depths of equivalent dipole polarizability resolution for some transmitter receiver configurations
- LBNL Library
Equivalent dipole polarizability matrices and equivalent dipole location are a convenient way to summarize magnetic induction data arising from currents induced in isolated conductive objects. The uncertainties in polarizability estimates and in equivalent dipole location provide a quantitative measure of the performance of different configurations of transmitters and receivers. Uncertainties in equivalent dipole polarizability matrices and equivalent dipole position are estimated using a linearized inversion. For a number of systems of rectangular loop transmitters and dipole receivers sited on a horizontal grid, equivalent dipole depth is determined to 10% approximately 20% deeper, than the polarizability matrix elements can be determined to the same precision. Systems that have a lower product of rms polarizability uncertainty and square root of their number of transmitter-receiver pairs are considered more effective for their number of transmitter-receiver pairs. Among the systems studied, a system with three orthogonal transmitter loops and a three component receiver is the most effective, for objects shallower than 0.6 times the instrument siting grid spacing, yielding an rms polarizability uncertainty 0.04 times that of a single transmitter single receiver system. At intermediate depths, a system with two vertical component receivers on the diagonal of a horizontal transmitter loop is most effective for its number of transmitter-receiver pairs, yielding an rms polarizability uncertainty 0.07 times that of a single receiver system. At depths greater than 2.5 times the siting grid spacing a 3 orthogonal loop transmitter with a single vertical component receiver is about the most effective for its number of transmitter-receiver pairs, yielding an rms polarizability uncertainty 0.08 times that of a single transmitter system.
- Research Organization:
- Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
- Sponsoring Organization:
- U.S. Dept. of the Army. Contract W74RDV93447299 (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 825039
- Report Number(s):
- LBNL--50636
- Country of Publication:
- United States
- Language:
- English
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