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Investigation of Ionizing Radiation Infuence to the Communication Systems of Satellites
Golubev, Martin ; Hobst, Leonard (referee) ; Katovský, Karel (advisor)
This master thesis discuss about ionizing radiation, interaction with matter and effects on her. In the work is discussed differend types of interactions of directly ionizing radiation and indirectly ionizing radiation. Below is an overview of methods of shielding from all of types of ionizing radiation. Second part of this thesis discuss about single event effects in semiconductors which are cause by ionizing radiation. At the end is described design of measuring instrument included FPGA chips. This design is discused both from point of wiew hardware and software too.
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Fast solar wind helium abundance variations and their relations to solar processes
Ďurovcová, Tereza ; Šafránková, Jana (advisor) ; Vandas, Marek (referee)
Helium can significantly influence solar wind dynamics. The changes of its relative abundance are usually associated with crossings of the boundaries between adjacent flux tubes. However, the recent studies of the data from the BMSW instrument onboard the Spektr-R spacecraft show that the relative helium abundance could vary also inside the flux tubes. The differential motion of proton and helium solar wind components was suggested as a source of turbulence inside the flux tube. The thesis is devoted to the long-term statistical study of the fast helium abundance variations with respect to parameters of the solar wind and changes of its source region. For this purpose, the plasma data from the instruments onboard the Wind and the Spektr-R spacecraft and magnetic field measurements from Wind were used. Simultaneous changes of the relative helium abundance and solar wind parameters were investigated in the long-term Wind observations as well as in the observations prior to and behind interplanetary shocks. Finally, the study of differences between proton and helium velocities during solar minima and solar maxima was conducted.
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Selected Wave Phenomena in the Earth's Magnetosphere
Bezděková, Barbora ; Němec, František (advisor) ; Macúšová, Eva (referee)
Electromagnetic waves are crucial for energy transfer in the nearly collision- less plasma of the Earth's inner magnetosphere. The waves in the frequency range 1-8 kHz whose visualisation in the form of frequency-time spectrograms reveals a harmonic frequency modulation of the wave intensity are called magnetospheric line radiation (MLR). Waves characterized by a nearly periodic time modulation of the wave intensity observed at frequencies between about 0.5 and 4 kHz are called quasiperiodic (QP) emissions. Although both types of the events were re- peatedly observed by ground-based instruments and low-altitude satellites, their origin remains still unclear. Between 2004 and 2010 these wave events were me- asured by the DEMETER spacecraft (almost Sun-synchronous orbit, altitude of about 700 km). This thesis presents a systematic study of the properties of the observed events, a comparison of the observations by the spacecraft and ground- based instruments, and an investigation of a relation to solar wind parameters.
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MHD discontinuities in the solar wind and their relation to processes in the Earth magnetosphere
Goncharov, Oleksandr ; Šafránková, Jana (advisor) ; Souček, Jan (referee) ; Vandas, Marek (referee)
1 Title: MHD discontinuities in the solar wind and their relation to processes in the Earth magnetosphere Author: Oleksandr Goncharov Department / Institute: Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University Supervisor of the doctoral thesis: Prof. RNDr. Jana Safrankova, DrSc Abstract: Collisionless shocks are ubiquitous in the heliosphere from the outer corona to the termination shock. They play an important role in the interaction of the solar wind with the planets because they efficiently convert the energy of the directed ion flow into the energy of heated ions and electrons, the energy of the enhanced magnetic field, and the energy of the accelerated particles. The leading idea of the thesis is to investigate evolution of distinct solar wind features, predominantly interplanetary shocks, within the solar wind, their interaction with the outer magnetospheric boundaries (magnetopause and bow shock), and to follow a path of resulting discontinuities through the magnetosphere up to its far tail. The methodology is based on the statistical evaluation of multispacecraft observations as well as on case studies of particular events. Some experimental investigations are supported with computer modeling. Moreover, an application of fast plasma measurements of the...
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Role of Magnetosheath Parameters on Magnetopause Processes
Krupařová, Oksana ; Šafránková, Jana (advisor)
The thesis addresses of two regions significant for the solar wind-magnetosphere coupling: the cusp in high geomagnetic latitudes and the low-latitude (LLBL) subsolar magnetopause. A penetration of plasma of a solar origin into the magnetosphere could be realized directly through magnetospheric cusps. The region adjacent to the magnetopause in the cusp vicinity is highly turbulent, occupied by the heated magnetosheath-like plasma with a low drift velocity for which occurrence of vortices is a very common feature. In the first part of the thesis, we present a detailed analysis of a vortex-like structure created by a turbulent plasma flow around the magnetopause indentation above the cusp and using the data from Interball-1 and Magion-4; we find necessary conditions and a possible mechanisms to creation of such structures. The second part concerns the low-latitude boundary layer formation, its spatial structure and temporal changes based on THEMIS multipoint observations. In spite of its crucial role in transfer of mass, momentum, and energy from the solar wind into the magnetosphere, LLBL parameters and their relations to upstream conditions are still under debate. We demonstrate that sudden changes in upstream plasma and magnetic field parameters could lead to reformation of the spatial LLBL profile from...
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Relationship of helium abundance in the solar wind to solar activity
Cagaš, Petr ; Šafránková, Jana (advisor) ; Vandas, Marek (referee)
Rapid changes in relative helium abundance in solar wind are often attributed to the flux tube crossings - thus between solar wind streams coming from different parts of the solar corona. Recent studies however show, that the changes in relative helium abundance are not always correlated with changes in other parameters and therefore the relative helium abundance could be changed even during the propagation of solar wind inside a flux tube. The topic of this thesis is an analysis of rapid changes of solar wind parameters and their mutual connection. Using a multipoint (we use data from the SPEKTR-R, WIND and the THEMIS spacecraft) case study of interplanetary shocks, we show that a possible explanation of those changes could be a magnetosonic instability excited by the differential flow between helium and proton populations.
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Proposal of detector for measurements of plasma environment near the Moon
Ďurovcová, Tereza ; Šafránková, Jana (advisor) ; Vaverka, Jakub (referee)
When the Moon is outside the Earth's magnetotail, its surface is directly ex- posed to the particles coming from the Sun. It is a consequence of a fact that the lunar surface is not protected by a global magnetic field or atmosphere. However, small-scale crustal magnetic fields have been found near the lunar surface; some of them can form so-called minimagnetospheres. Consequently, the vicinity of the Moon represents an interesting environment for the study of many processes in the solar wind plasma. The thesis is devoted to the proposal of a configuration of detectors for measurements of parameters in this plasma environment. The new device BMSW-LG which consists of the proposed configuration of detec- tors should monitor at 50−100 km altitude above the lunar surface on an orbit perpendicular to the ecliptic, and simultaneously compare the results with solar wind measurements. Experiences with the BMSW device were applied to this proposal. The SIMION software package which allows to test the trajectories of charged particles in electric fields inside the detector was used for simulations of the detector configuration.
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Magnetospheric line radiation observed by the DEMETER spacecraft
Bezděková, Barbora ; Němec, František (advisor) ; Sochorová, Zuzana (referee)
Frequency-time spectrograms of electromagnetic waves observed in the Earth's inner magnetosphere in the frequency range 1-8 kHz sometimes contain nearly horizontal and almost parallel intense lines. Such events were observed both by ground-based instruments and satellites, and they are called Magnetospheric Line Radiation (MLR). We systematically analyze 1230 MLR events identified in the data of the DEMETER spacecraft (2004-2010, altitude of about 700 km). We focus on a possible connection between the event occurrence and solar wind parameters. Long analyzed data interval allows us to evaluate a possible influence of the solar cycle and season of the year. We show that there is a statistically significant correlation between MLR events and solar wind parameters, and that the events are observed more often during the winter months and preferably during the solar maximum. The events occur less frequently at geomagnetic longitudes of South Atlantic Anomaly (SAA). We analyze spectra of energetic electrons precipitating in this region at the times of MLR events, which are supposed to be related to the wave generation. Powered by TCPDF (www.tcpdf.org)
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Solar wind helium abundance variations
Cagaš, Petr ; Šafránková, Jana (advisor) ; Enžl, Jakub (referee)
The thesis presents results of one-year measurements of solar wind helium ion abundance variations with the BMSW instrument on-board the SPEKTR-R spacecraft. The BMSW instrument was designed and built for fast measurements of the solar wind and can obtain a complete cumulative distribution function of solar wind particles every 1.5 s. A statistical study of the data shows that in spite of the current prevailing opinion, abrupt changes in the relative helium abundance do not correlate with the changes in other parameters of the solar wind and are therefore likely caused by in-transit turbulence that contributes to the solar wind heating and leads to rise of the solar wind temperature with the helium content.
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Application of Geomagnetic Data and Solar Physics for Education of Sciences in Secondary School
BAYER, Tomáš
This docement summarizes current geophysiscs and solar physics knowledge collection and applies it in grammar school education. Document explains significance of Earth geomagnetic field for whole biota and their evolution and includes current knowledge of geophysics and solar physics to the Programme for Secondary General Education (Grammar Schools). The document introduces actual findings of solar physics and geophysics (especially geomagnetism) to the educational area Man and Nature containing synthetic education of biology and geosciences. The main method of this document is comparison and explanation of solar physics satellite data, explanation of solar disc records and solar wind time series. This data have been compared by Czech national Geomagnetic observatory (IAGA code BDV) variograms and enables pupils to process satellite and observatory real-time data.
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