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dc.contributor.advisorGarcia, Odd Erik
dc.contributor.advisorKube, Ralph
dc.contributor.authorDecristoforo, Gregor
dc.date.accessioned2016-11-22T13:22:08Z
dc.date.available2016-11-22T13:22:08Z
dc.date.issued2016-05-18
dc.description.abstractIntermittent fluctuations and turbulence-induced transport of magnetically confined fusion plasmas are investigated by numerical computations. A reduced fluid model describing the evolution of plasma pressure and electric drift vorticity in a two-dimensional plane perpendicular to the magnetic field is derived. A numerical simulation code implemented on graphical processing units is presented. We observe significant speedup compared to sequential Fortran implementations. The convective motions are driven by a constant incoming heat flux at the inner radial boundary of the domain. We identify different transport and confinement states. We observe stationary convection and self-sustained shared flows for low heat flux drive. For increasing drive, oscillatory motion with sheared flows arise until the system enters a state of turbulent convection. At the onset of turbulent convection we observe that the probability density functions of the normalized radial velocity, pressure and flux fluctuations show nearly Gaussian form. This distributions get increasingly non-Gaussian and develop exponential tails for increasing heat flux drive. We observe quasi-periodic bursts at the state of intermittent convection, separated by quiescent periods. The waiting time and amplitude distribution of these bursts take a nearly exponential form. The conditionally averaged waveform and the autocorrelation function of the normalized pressure fluctuations are discussed. We further compare those results to experimental measurements and predictions from stochastic modelling and find very good agreement.en_US
dc.identifier.urihttps://hdl.handle.net/10037/9991
dc.language.isoengen_US
dc.publisherUiT Norges arktiske universiteten_US
dc.publisherUiT The Arctic University of Norwayen_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2016 The Author(s)
dc.rights.urihttps://creativecommons.org/licenses/by-nc-sa/3.0en_US
dc.rightsAttribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0)en_US
dc.subject.courseIDFYS-3900
dc.subjectVDP::Mathematics and natural science: 400::Physics: 430en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Fysikk: 430en_US
dc.titleNumerical computations of turbulent motions in magnetized plasmasen_US
dc.typeMaster thesisen_US
dc.typeMastergradsoppgaveen_US


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Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0)
Except where otherwise noted, this item's license is described as Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0)