Sökning: "magnetic field oscillations"

Visar resultat 1 - 5 av 44 avhandlingar innehållade orden magnetic field oscillations.

1. 1. Excitons in a high magnetic field

   Författare :Alexandre V. Petrov; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Fysik; Physics; Fysik; fysik; Physics;

   Sammanfattning : The interaction of excitons with each other and with charged impurities has been studied in a high magnetic field when the distance between the Landau levels is greater than the Coulomb unit of energy, in the frame of the model suitable for description of Wannier excitons in semiconductors. The analytical expressions for the pair interaction potential between hydrogenlike excitons in a high magnetic field are derived for the triplet and singlet terms. LÄS MER

3. 2. Plasma environment of an intermediately active comet : Evolution and dynamics observed by ESA's Rosetta spacecraft at 67P/Churyumov-Gerasimenko

   Författare :Elias Odelstad; Anders Eriksson; Andrew Coates; Uppsala universitet; []
   Nyckelord :Rosetta; comet; 67P; RPC-LAP; RPC-MIP; RPC-ICA; RPC-MAG; ROSINA-COPS; Langmuir probe; spacecraft potential; plasma; Churyumov-Gerasimenko; ion composition analyzer; diamagnetic cavity; ion velocity; electron temperature; ion-neutral drag; collisional coupling; wake effects; filamentation; electron cooling; plasma waves; hybrid waves; Bernstein waves; minimum variance; polarization; wavelet; density fluctuations; magnetic field oscillations; drift-cyclotron instability; asymmetric plasma and magnetic field enhancements; Fysik med inriktning mot rymd- och plasmafysik; Physics with specialization in Space and Plasma Physics;

   Sammanfattning : The subject of this thesis is the evolution and dynamics of the plasma environment of a moderately active comet before, during and after its closest approach to the Sun. For over 2 years in 2014-2016, the European Space Agency’s Rosetta spacecraft followed the comet 67P/Churyumov-Gerasimenko at distances typically between a few tens and a few hundred kilometers from the nucleus, the longest and closest inspection of a comet ever made. LÄS MER

4. 3. Effects of the Spin-Orbit Interaction on Transport and Optical Properties of III-V Semiconductor Quantum Wells

   Författare :Vladimir Froltsov; Matematisk fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; spin-orbit interaction; quantum well; III-V; Raman scattering; magnetoresistance; weak localization; spin distribution; magnetic field; Fysik; Physics; Fysicumarkivet A:2000:Froltsov; Halvledarfysik; Semiconductory physics; semiconductor;

   Sammanfattning : Effects of the intrinsic electron spin-orbit interaction on transport and optical properties of III-V semiconductor quantum wells have been studied theoretically. It is shown that due to crystal anisotropy of this interaction, the weak localization magnetoresistance in a magnetic field parallel to interfaces is very sensitive to the epitaxy growth direction and also to the orientation of the magnetic field with respect to the crystal axes. LÄS MER

5. 4. Some Control Applications in Electric Power Systems

   Författare :Magnus Akke; Industriell elektroteknik och automation; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; load switching.; power oscillations; differential equation algorithm; transmission line protection; computer relaying; frequency estimation; DC cable; magnetic compass; Automation; robotics; control engineering; Automatiska system; robotteknik; reglerteknik;

   Sammanfattning : This thesis presents some control applications in electric power systems. The work consists of the four parts: interaction between DC cables and ship steering autopilots; frequency estimation; computer relaying; field tests using load switching to damp power oscillations. LÄS MER

7. 5. Interaction between Electromagnetic Waves and Localized Plasma Oscillations

   Författare :Jan-Ove Hall; Thomas Leyser; Jan Trulsen; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Space and plasma physics; space physics; plasma physics; radio waves; ionospheric modification; density depleations; field-aligned irregularities; lower hybrid solitary structures; lower hybrid cavities; Z mode waves; magnetosonic waves; scattering; mode conversion; Rymd- och plasmafysik; Space physics; Rymdfysik;

   Sammanfattning : This thesis treats interaction between electromagnetic waves and localized plasma oscillations. Two specific physical systems are considered, namely artificially excited magnetic field-aligned irregularities (striations) and naturally excited lower hybrid solitary structures (LHSS). LÄS MER