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Nonlinear processes in space plasmas and their effects on the generation and propagation of electromagnetic waves
Hanzelka, Miroslav ; Santolík, Ondřej (advisor) ; Hellinger, Petr (referee) ; Rycroft, Michael J. (referee)
Nonlinear interactions of charged particles and large-amplitude waves have a signif- icant impact on magnetospheric dynamics. Here we focus on the cyclotron resonant interaction between energetic electrons and the discrete, whistler-mode chorus emissions in the Earth's outer radiation belt. The subject is introduced by an extensive review of whistler-mode dispersion properties, resonant electron trajectories and nonlinear wave- growth theories. We then present a new semi-empirical model of rising-tone chorus emis- sions with a fine subpacket structure. The model is then used in test-particle simulations to investigate nonlinear perturbations in hot electron distributions. Based on changes in electron fluxes, we estimate the resolution of spacecraft particle detectors required to detect the predicted perturbations. The test-particle method is further used to sim- ulate atmospheric precipitation of electrons caused by interaction with a single chorus wavepacket, and the result is put into connection with microbursts and pulsating auro- ras. We also detected a violation of the strong diffusion limit by the cyclotron resonant interaction, resulting in loss cone overfilling. 1
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Turbulence in the solar wind from inertial to kinetic scales
Pitňa, Alexander ; Šafránková, Jana (advisor) ; Hellinger, Petr (referee) ; Kulhánek, Petr (referee)
Solar wind, a stream of supersonic plasma emanating from the solar corona, serves as an ideal laboratory for a study of high Reynolds number plasma flows. Turbulent processes that govern the dynamics of the so-called inertial range, i.e., the spatial scales smaller than energy injection scales but larger than the scales where the dissipation processes set in, have been studied for decades. At present, it is believed that the large-scale free energy in a form of kinetic and magnetic fluctuations is transferred via turbulent cascade into smaller scales, where kinetic effects become dominant and heating takes place. In order to understand dissipation processes, high-cadence measurements of solar wind parameters are necessary. The bright monitor of the solar wind (BMSW) instrument on board the Spektr-R spacecraft provides such data, and in tandem with high-cadence measurements of the magnetic field from the Wind spacecraft, we are able address the nature of the sub-ion scale fluctuations. The thesis focus on three interconnected topics, (a) what changes are induced by the passage of a collisionless IP shock in the framework of turbulence, (b) study of a decay of the turbulent energy downstream an IP shock, and (c) identifying the dominant mode of the sub-ion scale fluctuations.
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Turbulence in the solar wind from inertial to kinetic scales
Pitňa, Alexander ; Šafránková, Jana (advisor) ; Hellinger, Petr (referee) ; Kulhánek, Petr (referee)
Solar wind, a stream of supersonic plasma emanating from the solar corona, serves as an ideal laboratory for a study of high Reynolds number plasma flows. Turbulent processes that govern the dynamics of the so-called inertial range, i.e., the spatial scales smaller than energy injection scales but larger than the scales where the dissipation processes set in, have been studied for decades. At present, it is believed that the large-scale free energy in a form of kinetic and magnetic fluctuations is transferred via turbulent cascade into smaller scales, where kinetic effects become dominant and heating takes place. In order to understand dissipation processes, high-cadence measurements of solar wind parameters are necessary. The bright monitor of the solar wind (BMSW) instrument on board the Spektr-R spacecraft provides such data, and in tandem with high-cadence measurements of the magnetic field from the Wind spacecraft, we are able address the nature of the sub-ion scale fluctuations. The thesis focus on three interconnected topics, (a) what changes are induced by the passage of a collisionless IP shock in the framework of turbulence, (b) study of a decay of the turbulent energy downstream an IP shock, and (c) identifying the dominant mode of the sub-ion scale fluctuations.
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L-DEPP Definition Study for Lunar Lander FINAL REPORT "
Trávníček, Pavel M. ; Štverák, Štěpán ; Hellinger, Petr ; Herčík, David ; Laifr, Jaroslav ; Pavelka, Roman ; Váňa, P. ; Břínek, J. ; Kozáček, Z. ; Rucker, H. ; Sampl, M. ; Auster, U. ; Glassmeier, K. - H. ; Kataria, D. ; Owen, C. J. ; Farrell, W.M. ; MacDowall, R. J. ; Sternovsky, Z. ; Horanyi, M. ; Delory, G.T. ; Turin, P.
A complete set of scientific instrumentation for the L-DEPP dust, plasma and waves package for the ESA Lunar Lander mission has been proposed and fully assessed with respect to the system and scientific requirements derived by ESA and the L-DEPP project team. The preliminary design from the system level down to the individual sensors is presented.
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