Sökning: "plasma astrophysics"

Visar resultat 1 - 5 av 34 avhandlingar innehållade orden plasma astrophysics.

1. 1. Gravitational perturbations in plasmas and cosmology

   Författare :Mats Forsberg; Gert Brodin; Michael Bradley; Christopher Clarkson; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; general relativity; cosmology; gravitational waves; plasma; electromagnetic waves; nonlinear waves; Plasma physics; Plasmafysik; Theory of relativity; gravitation; Relativitetsteori; gravitation; Cosmology; Kosmologi; teoretisk fysik; Theoretical Physics;

   Sammanfattning : Gravitational perturbations can be in the form of scalars, vectors or tensors. This thesis focuses on the evolution of scalar perturbations in cosmology, and interactions between tensor perturbations, in the form of gravitational waves, and plasma waves. LÄS MER

3. 2. Theoretical Atomic Spectroscopy of Earthbound and Stellar Plasma

   Författare :Jon Grumer; Matematisk fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; atomstruktur; atomära processer; elektronkorrelation; plasmaspektroskopi; magnetfält; hyperfinstruktur; solkoronan; rymdväder; förekomst av grundämnen i stjärnor; datorsimuleringar; Zeemaneffekt; relativistiska effekter; atomic structure; atomic processes; computer simulation; electron correlation; relativistic atomic theory; plasma spectroscopy; Zeeman effect; magnetic fields; hyperfine structure; solar corona; space weather; stellar abundances; Fysicumarkivet A:2016:Grumer;

   Sammanfattning : Motivated by spectroscopic analysis of astrophysical and laboratory plasma, this thesis concerns the fundamental structure and spectral properties of atoms and their ions. The multiconfiguration Dirac-Hartree-Fock (MCDHF) method is used to predict the emission or absorption of radiation, by atomic systems in general, and of heavy and highly charged ions in particular. LÄS MER

4. 3. Global Turbulent EquiPartition (TEP) in Tokamak Plasma

   Författare :Igor A. Ivonin; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; turbulent plasma; TEP; scaling laws; transport barrier; tokamak; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Space and Plasma Physics; rymd- och plasmafysik;

   Sammanfattning : We studied analytically and numerically the establishment of global turbulent equipartition (TEP) of magnetised electrons in a tokamak plasma. This allows us to investigate self-consistently the inhomogeneous distributions of the plasma density, the electron and the ion temperatures, the generation of radial electric field and the poloidal and the toroidal rotation in the turbulent tokamak plasma. LÄS MER

5. 4. Drift and Mirror Modes in Magnetized Plasmas

   Författare :Ingmar Sandberg; Padma Shukla; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; tokamak plasma; drift waves; space plasma; mirror instability.; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; Space and Plasma Physics; rymd- och plasmafysik;

   Sammanfattning : Low frequency plasma instabilities driven by plasma inhomogeneity and velocity anisotropies are major candidates for the explanation of various phenomena observed in fusion and space plasmas. For low-β fusion plasma, the influence of plasma rotation and finite ion temperature on the structure and the type of toroidal drift eigenmodes in tokamaks is investigated rigorously, including the effects induced by the toroidal geometry such as the coupling mode, the radial variation of plasma rotation velocity and the magnetic shear. LÄS MER

7. 5. A Cosmic Quest for New Worlds. Characterising Exoplanet Signals via Radial Velocity and Transit Photometry

   Författare :Iskra Georgieva; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Exoplanet; transits; radial velocities; planetary systems;

   Sammanfattning : Since the first unambiguous detection of a planet around a Sun-like star, the interest in the new and exciting field of exoplanets has grown immensely. New and exciting developments are seen at a pace unparalleled for most subfields of astronomy. LÄS MER