Search for dissertations about: "collisional coupling"

Found 4 swedish dissertations containing the words collisional coupling.

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

    Author : Elias Odelstad; Anders Eriksson; Andrew Coates; Uppsala universitet; []
    Keywords : 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;

    Abstract : 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. READ MORE

  4. 2. On Monte Carlo Operators for Studying Collisional Relaxation in Toroidal Plasmas

    Author : Qaisar Mukhtar; Torbjörn Hellsten; Tainia Kurki-Suonio; KTH; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Fusion plasma; thermonuclear fusion; tokamak; Coulomb collisions; stochastic differential equations with singular diffusion coefficients; Monte Carlo schemes; spatial diffusion; modelling; Fokker-Planck equation; RF-heating.;

    Abstract : This thesis concerns modelling of Coulomb collisions in toroidal plasma with Monte Carlo operators, which is important for many applications such as heating, current drive and collisional transport in fusion plasmas. Collisions relax the distribution functions towards local isotropic ones and transfer power to the background species when they are perturbed e. READ MORE

  5. 3. Atomic Processes in Stellar Atmospheres : Inelastic Collisions and Effects on Late-type Spectra

    Author : Yeisson Fabian Martinez Osorio; Paul Barklem; Karin Lind; Nikolai Piskunov; Carlos Allende Prieto; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Spectral line: formation; atomic data; stellar abundances.; Fysik med inriktning mot astrofysik; Physics with specialization in Astrophysics;

    Abstract : Chemical abundances as measured from stellar spectral lines are often subject to uncertainties due to lack of accurate data for inelastic collisions, which is needed for non-local thermodynamic equilibrium (non-LTE) modelling. For cool stars, understanding of collision processes with electrons and hydrogen atoms is required to achieve high precision measurements. READ MORE

  6. 4. Experimental Studies of Quantum Dynamics and Coherent Control in Homonuclear Alkali Diatomic Molecules

    Author : Bo Zhang; KTH; []
    Keywords : ultrafast laser spectroscopy; pump-probe technique; predissociation; wavepacket; spin-orbit interaction; coherent control; dephasing;

    Abstract : The main theme covered in this thesis is experimentalstudies of quantum dynamics and coherent control in homonuclearalkali diatomic molecules by ultrafast laser spectroscopy iththe implementation of pump-probe techniques.A series of experiments have been performed on the Rb2molecules in a molecular beam as well as in a thermal oven. READ MORE