Search for dissertations about: "plasma modeling"

Showing result 1 - 5 of 115 swedish dissertations containing the words plasma modeling.

2. 1. Resonant magnetic perturbation effect on the tearing mode dynamics : Novel measurements and modeling of magnetic fluctuation induced momentum transport in the reversed-field pinch

   Author : Richard Fridström; Per Brunsell; Lorenzo Frassinetti; Tommaso Bolzonella; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; RFP; reversed-field pinch; tokamak; tearing mode; RMP; fusion; plasma; resonant magnetic perturbation; stochastic; magnetic; field; viscosity; mode; locking; Electrical Engineering; Elektro- och systemteknik;

   Abstract : The tearing mode (TM) is a resistive instability that can arise in magnetically confined plasmas. The TM can be driven unstable by the gradient of the plasma current. When the mode grows it destroys the magnetic field symmetry and reconnects the magnetic field in the form of a so-called magnetic island. READ MORE

4. 2. Numerical modeling of auroral processes

   Author : Jörgen Vedin; Kjell Rönnmark; Robert Lysak; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; space plasma physics; auroral acceleration region; auroral current circuit; Alfvén waves; parallel electric fields; equation of state; fluid simulation; PIC simulation; Space physics; Rymdfysik;

   Abstract : One of the most conspicuous problems in space physics for the last decades has been to theoretically describe how the large parallel electric fields on auroral field lines can be generated. There is strong observational evidence of such electric fields, and stationary theory supports the need for electric fields accelerating electrons to the ionosphere where they generate auroras. READ MORE

5. 3. Kinetic modeling of runaway-electron dynamics in partially ionized plasmas

   Author : Linnea Hesslow; Chalmers tekniska högskola; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; runaway electrons; tokamaks; plasma physics; magnetic confinement fusion; electron-ion collisions; Fokker-Planck equation;

   Abstract : An essential result of kinetic plasma physics is the runaway phenomenon, whereby a fraction of an electron population can be accelerated to relativistic energies. Such runaway electrons are formed in astrophysical settings, but are also of great practical relevance to fusion research. READ MORE

6. 4. Empirical Modeling of Solar Induced Variations of Nitric Oxide in the Upper Mesosphere and Lower Thermosphere

   Author : Joonas Kiviranta; Chalmers tekniska högskola; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; mesosphere; nitric oxide; Odin; thermosphere; empirical modeling; SANOMA;

   Abstract : Nitric Oxide (NO) is produced by solar photolysis and auroral activity in the upper mesosphere and lower thermosphere region and can, via transport processes, eventually impact the ozone layer in the stratosphere. This thesis uses measurements of NO taken between 2004 and 2016 by the Odin Sub Millimetre Radiometer (SMR) to build an empirical model which links the prevailing solar and auroral conditions with the measured number density of NO. READ MORE

7. 5. Fuel ion densities and distributions in fusion plasmas : Modeling and analysis for neutron emission spectrometry

   Author : Jacob Eriksson; Göran Ericsson; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Applied Nuclear Physics; Tillämpad kärnfysik;

   Abstract : Neutrons produced in fusion reactions in a magnetically confined plasma carry information about the distributions and densities of the fuel ions in the plasma. This thesis presents work where various theoretical models of different fuel ion distributions in the plasma are used to calculate modeled components of the neutron energy spectrum. READ MORE