Sökning: "drift waves"

Visar resultat 6 - 10 av 37 avhandlingar innehållade orden drift waves.

1. 6. Influence of Geometry on Drift Waves in Tokamaks and Stellarators

   Författare :Tariq Rafiq; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; ITG; local magnetic shear; linear instabilities; drift waves;

   Sammanfattning : There is a general consensus that drift waves are responsible for a large amount of transport in fusion experiments and it is of importance to investigate their linear stability and nonlinear evolution. These instabilities have therefore been intensively investigated in tokamaks for the last few decades. LÄS MER

3. 7. 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. 8. 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

5. 9. VLF and ULF Waves Associated with Magnetospheric Substorms

   Författare :Andrew Collier; Lars Blomberg; James McKenzie; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Space physics; Subtorms; Magnetosphere; VLF waves; ULF waves; Space physics; Rymdfysik;

   Sammanfattning : A magnetospheric substorm is manifested in a variety of phenomena observed both in space and on the ground. Two electromagnetic signatures are the Substorm Chorus Event (SCE) and Pi2 pulsations. The SCE is a Very Low Frequency (VLF) radio phenomenon observed on the ground after the onset of the substorm expansion phase. LÄS MER

7. 10. Two cases of nonlinear waves in plasma : echo in weak turbulence and solitary drift vortices

   Författare :Jonas Nycander; Uppsala universitet; []
   Nyckelord :NATURAL SCIENCES; NATURVETENSKAP;

   Sammanfattning : .... LÄS MER