Measurement of Declination and Inclination Angles of the Earth's Magnetic Field Using a Pair of Barker Coil Systems and a Proton Magnetometer

摘要

Applying homogeneous bias fields to a Proton Precession Magnetometer (PPM) can facilitate measurement of vector components of the Earth's magnetic field accurately. This paper describes a Vector Proton Precession Magnetometer (referred as dIdD VPPM) which was designed using a PPM and two pairs of Barker coil systems mounted orthogonal to each other and to an axis which is aligned along the Ibcal magnetic field direction. This orthogonal coil arrangement is used with the Proton Magnetometer to get deflected Inclination (dI) - deflected Declination (dD) and total field F from which absolute values of Declination, Inclination, Horizontal Intensity H and vertical Intensity Z can be computed. The time series variations dl and dD from dIdD VPPM are compared with that of DFM. From the recorded instantaneous values of I and D by VPPM at Alibag M.O, total I and D were computed. Scatter plots of the various components Earth's field were analyzed using the data recorded at Alibag M.O by two standard Instruments namely Digital Fluxgate Magnetometer (DFM) and dIdD VPPM. It was found after analysis that maximum scatter in D and I are less than few nTs. Correlation Coefficients were calculated from these scatter plots. They are in the range 0.96 to 0.99. Results obtained from a prototype System model over a period of several months shows that dIdD VPPM system can provide adequate absolute field values for maintaining observatory calibration data.