Browsing by Author "Väänänen, Mika"

For millennia, phenomena of the magnetosphere have intrigued mankind. Studies of the geomagnetic field were first initiated to locate precious minerals, later on continued for purposes of navigation and in the modern times for scientific interest and protection of modern society. Strong changes in the interplanetary magnetic field and pulses of charged particles originating from the Sun pose serious risks to many cornerstones of our lifestyle, such as the power grid, telecommunication and space safety. Understanding the interaction between the interplanetary magnetic field, solar wind and the geomagnetic field is crucial in building protection systems for these critical technologies. Magnetometers are practically the only instrument to monitor changed in the magnetic environment and thus a key instrument in broadening this understanding. In this thesis I describe two projects: development of a digitization algorithm for old, analog magnetometer data and the design and building process of two small magnetometers: one for ground based measurements and one for space applications. The aim of the digitization project was to digitize a magnetic timeseries produced in 1970s and 1980s. The quality of the dataset is very high, but since the data is saved on photographic film as graphs, proper time series analysis is difficult. During the project, I used a custom-made film scanner and developed a MATLAB program to read out the measured values from the scanned films. The aim of the magnetometer building project was to show that it is possible to build science grade magnetometers from commercial-off-the-shelf (COTS) components, enabling magnetometric campaigns where state of the art instruments would be prohibitively expensive. One magnetometer was built based on the Honeywell HMC5883L sensor, controlled by a Raspberry Pi miniature computer. This magnetometer was placed at the Metsähovi Radio Observatory. Another magnetometer, the CubeMAG, was based on the Honeywell HMC2003 sensor and controlled by an STM32F100 microcontroller. This magnetometer will be one of the science payloads of the ESTCube-2 satellite. The magnetometer placed in Metsähovi showed promising results, recording one strong geomagnetic storm which was also recorded with observatory quality instruments at the Nurmijärvi geophysical observatory. The resolution of the HMC5883L was too low to record most interesting features of the storm, but was high enough to show that the Metsähovi observatory is a suitable place for a more sensitive magnetometer. As of writing this thesis, ESTCube-2 is in development and preparing for launch and scientific results from the CubeMAG are not available. Initial laboratory tests show promising results, with the significantly higher resolution of the HMC2003 compared to the HMC5883L being able to record very small changes in the surrounding magnetic field.