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dc.contributor.advisorSchekochihin, Alex
dc.contributor.advisorPapaloizou, John
dc.contributor.authorRosin, Mark
dc.date.accessioned2011-05-24T08:24:11Z
dc.date.available2011-05-24T08:24:11Z
dc.date.issued2011-02-08
dc.identifier.otherPhD.34053
dc.identifier.urihttp://www.dspace.cam.ac.uk/handle/1810/237241
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/237241
dc.description.abstractIn a magnetized plasma, naturally occurring pressure anisotropies facilitate in- stabilities that are expected to modify the transport properties of the system. In this thesis we examine two such instabilities and, where appropriate, their effects on transport. First we consider the collisional (fluid) magnetized magnetorotational instability (MRI) in the presence of the Braginskii viscosity. We conduct a global linear analysis of the instability in a galactic rotation profile for three magnetic field configurations: purely azimuthal, purely vertical and slightly pitched. Our analysis, numerical and asymptotic, shows that the first two represent singular configurations where the Braginskii viscosity’s primary role is dissipative and the maximum growth rate is proportional to the Reynolds number when this is small. For a weak pitched field, the Braginskii viscosity is destabilising and when its effects dominate over the Lorentz force, the growth rate of the MRI can be up to 2√2 times faster than the inviscid limit. If the field is strong, an over-stability develops and both the real and imaginary parts of the frequency increase with the coefficient of the viscosity. Second, in the context of the ICM of galaxy clusters, we consider the pressure-anisotropy-driven firehose instability. The linear instability is fast (∼ ion cyclotron period) and small-scale (ion Larmor radius ρi) and so fluid theory is inapplicable. We determine its nonlinear evolution in an ab initio kinetic calculation (for parallel gradients only). We use a particular physical asymptotic ordering to derive a closed nonlinear equation for the firehose turbulence, which we solve. We find secular (∝ t) growth of magnetic fluctuations and a k−∥3 spectrum, starting at scales >~ ρi. When a parallel ion heat flux is present, the parallel firehose instability mutates into the new gyrothermal instability. Its nonlinear evolution also involves secular magnetic energy growth, but its spectrum is eventually dominated by modes with a maximal scale ∼ρilT/λmfp,(lT is the parallel temperature gradient scale). Throughout we discuss implications for modelling, transport and other areas of magnetized plasma physics.en_GB
dc.description.sponsorshipSTFC (Science and Technology Facilities Council) PhD studentshipen_GB
dc.language.isoenen_GB
dc.rightsAll Rights Reserveden
dc.rights.urihttps://www.rioxx.net/licenses/all-rights-reserved/en
dc.subjectPlasmaen_GB
dc.subjectMagnetic fielden_GB
dc.subjectFluiden_GB
dc.subjectKineticen_GB
dc.subjectMagnetizeden_GB
dc.subjectFirehose instabilityen_GB
dc.subjectMagnetorotational instatbilityen_GB
dc.subjectMRIen_GB
dc.subjectTransporten_GB
dc.subjectGalaxy clustersen_GB
dc.subjectAccretion discen_GB
dc.subjectMHDen_GB
dc.titleInstabilities and transport in magnetized plasmasen_GB
dc.typeThesisen_GB
dc.type.qualificationlevelDoctoral
dc.type.qualificationnameDoctor of Philosophy (PhD)
dc.publisher.institutionUniversity of Cambridgeen_GB
dc.publisher.departmentDepartment of Applied Mathematics and Theoretical Physicsen_GB
dc.publisher.departmentDarwin Collegeen_GB
dc.identifier.doi10.17863/CAM.16100


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