Sökning: "rymd- och plasmafysik"
Visar resultat 6 - 10 av 83 avhandlingar innehållade orden rymd- och plasmafysik.
6. New Perspectives on Solar Wind-Magnetosphere Coupling
Sammanfattning : The streaming plasma in the solar wind is a never ending source of energy, plasma, and momentum for planetary magnetospheres, and it continuously drives large-scale plasma convection systems in our magnetosphere and over our polar ionosphere. This coupling between the solar wind and the magnetosphere is primarily explained by two different processes: magnetic reconnection at high latitudes, which interconnects the interplanetary magnetic field (IMF) with the planetary dipole field, and low-latitude dynamos such as viscous interaction, where the streaming plasma in the solar wind may trigger waves and instabilities at the flanks of the magnetosphere, and thereby allow solar wind plasma to enter into the system. LÄS MER
7. On the Properties of Ionospheric Convection
Sammanfattning : The solar wind interaction with the magnetosphere-ionosphere system continuously drives plasma convection in the polar regions of the ionosphere. The flow velocity and the shape of the convection pattern are closely dependent on the interplanetary conditions, in particular the direction of the interplanetary magnetic field (IMF). LÄS MER
8. Solitary waves and enhanced incoherent scatter ion lines
Sammanfattning : This thesis addresses solitary waves and their significance for auroral particle acceleration, coronal heating and incoherent scatter radar spectra. Solitary waves are formed due to a balance of nonlinear and dispersive effects. LÄS MER
9. A Simulation Approach to Plasma Waves
Sammanfattning : Electrostatic waves in the form of Broadband Electrostatic Noise (BEN) have been observed inthe Earth’s auroral region associated with high geomagnetic activity. Their broad frequencyspectrum consists of three electrostatic modes, namely electron plasma, electron acoustic andbeam-driven modes. LÄS MER
10. High Power Microwave Sources : design and experiments
Sammanfattning : High-Power Microwaves (HPM) can be used to intentionally disturb or destroy electronic equipment at a distance by inducing high voltages and currents. This thesis presents results from experiments with a narrow band HPM source, the vircator. LÄS MER