Christian Kwisanga received the B.Sc. and M.Sc. degrees in Applied Physics from the University of Science and Technology of Algiers, Algeria, in 2008 and 2010 respectively. In 2016, he obtained his Ph.D. degree in Electronic Engineering from Stellenbosch University, South Africa. Since 2011, he has been a Lecturer at the College of Science and Technology, University of Rwanda. His research interests include using advanced magnetometers to detect precursory geomagnetic signals associated to volcanic/seismic activity.
Due to its extreme sensitivity to magnetic flux, vast dynamic range and wide bandwidth, the Super... more Due to its extreme sensitivity to magnetic flux, vast dynamic range and wide bandwidth, the Superconductive Quantum Interference Device (SQUID) is at the frontier of all existing magnetic field sensors. The direct current SQUID principle is based on quantised flux induced current tunnelling across weak link barriers embedded in a superconductive ring. The SQUID can sense a field of the order of 10−15 T, in the same range as the neuron-cell magnetic activity and operates from quasi-dc to the GHz range. The extreme versatility of the SQUID technology makes it an instrument of choice in state-of-the-art applications including monitoring the Earth’s magnetic field. The geomagnetic field is by far one of the most complex systems, as it encompasses field generation phenomena inside the Earth, and the extension of the field into the near-Earth environment, where interaction of ions from the Sun, solar magnetic field and Earth’s magnetic field create a highly dynamic plasma system controlle...
Polarisation properties of the geomagnetic signal are computed using the coherence matrix of hori... more Polarisation properties of the geomagnetic signal are computed using the coherence matrix of horizontal components (EW and NS) of the [SQUID] 2 datasets, in a relatively small bandwidth. Wavefront ellipticity, signal-to-noise ratio (snr) and wavefront arrival angle of the magnetic quasi-monochromatic waves are determined. From the variation of ellipticity extremum position in the vicinity of 8 Hz, the temporal variation of the peak frequency is traced for the LSBB and two Northern American stations distant from the LSBB by ∼8, 000 km. The spectra of the peak frequency variation display the daily, half daily and third-daily harmonics at all stations, which are characteristic of the first Schumann resonance. Ellipticity spectrograms also unveil a type of chirping local nighttime resonances, known as ionospheric Alfvén resonances (IAR), observed at all stations. Thanks to the snr spectrograms, components of the signal which are local to the LSBB station are cancelled from the output, particularly the 50-Hz power grid signal which is minimised in the snr spectra.
Due to its extreme sensitivity to magnetic flux, vast dynamic range and wide bandwidth, the Super... more Due to its extreme sensitivity to magnetic flux, vast dynamic range and wide bandwidth, the Superconductive Quantum Interference Device (SQUID) is at the frontier of all existing magnetic field sensors. The direct current SQUID principle is based on quantised flux induced current tunnelling across weak link barriers embedded in a superconductive ring. The SQUID can sense a field of the order of 10−15 T, in the same range as the neuron-cell magnetic activity and operates from quasi-dc to the GHz range. The extreme versatility of the SQUID technology makes it an instrument of choice in state-of-the-art applications including monitoring the Earth’s magnetic field. The geomagnetic field is by far one of the most complex systems, as it encompasses field generation phenomena inside the Earth, and the extension of the field into the near-Earth environment, where interaction of ions from the Sun, solar magnetic field and Earth’s magnetic field create a highly dynamic plasma system controlle...
Polarisation properties of the geomagnetic signal are computed using the coherence matrix of hori... more Polarisation properties of the geomagnetic signal are computed using the coherence matrix of horizontal components (EW and NS) of the [SQUID] 2 datasets, in a relatively small bandwidth. Wavefront ellipticity, signal-to-noise ratio (snr) and wavefront arrival angle of the magnetic quasi-monochromatic waves are determined. From the variation of ellipticity extremum position in the vicinity of 8 Hz, the temporal variation of the peak frequency is traced for the LSBB and two Northern American stations distant from the LSBB by ∼8, 000 km. The spectra of the peak frequency variation display the daily, half daily and third-daily harmonics at all stations, which are characteristic of the first Schumann resonance. Ellipticity spectrograms also unveil a type of chirping local nighttime resonances, known as ionospheric Alfvén resonances (IAR), observed at all stations. Thanks to the snr spectrograms, components of the signal which are local to the LSBB station are cancelled from the output, particularly the 50-Hz power grid signal which is minimised in the snr spectra.
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