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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"Alfven waves"”.
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Stable Alfven Wave Dynamo Action in the Reversed Field Pinch
Previous theoretical work has suggested that Alfven waves may be related to the anomalous toroidal magnetic flux generation and extended (over classical expectations) discharge times observed in the reversed field pinch. This thesis examines the dynamo action of stable Alfven waves as a means of …
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The Equilibria, Stability and Nonlinear Dynamics of Magnetically Sheared Atmospheres With Applications to the Solar Environment
… Lorentz force which drives large amplitude shear Alfven waves. The Alfven waves provide an explanation for impulsive shearing motions at the photosphere in newly emerged bipolar active regions. Simulations of instabilities of sheared magnetic arcades indicate that self-induced, shear Alfven waves …
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A Three-Year Study of the Magnetic Field Fluctuations in the Magnetospheric Cusp
… Hz include mirror mode, ion-cyclotron, and Alfven waves. Sources of wave power from 0.1-10 Hz include ion-cyclotron and Alfven waves.</p>
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Numerical Simulation of Ion-Cyclotron Turbulence Generated by Artificial Plasma Cloud Release
… short wavelength ion cyclotron waves evolve nonlinearly into electromagnetic obliquely propagating shear Alfven waves with much longer wavelength. The results indicate that ring densities above a few percent of the background plasma density may produce wave amplitudes large …
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Multipoint measurements of field aligned current density in the auroral zone
… delay, which indicates the presence of localized Alfven waves and/or even more filamentary currents. The non-zero deflections in magnetic field magnitude might be considered as the presence of compressional Alfven waves. Further study of this event was done by applying wavelet transformation and …
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Mode conversion and wave -particle interaction processes in the solar wind
… velocity field on the propagation of waves in the solar atmosphere. We find that coupling between Alfven waves and fast magnetosonic waves can occur for parameters characterizing the coronal holes. For streamer conditions, the Alfven wave couples to the slow magnetosonic mode. In the …
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The role of magnetic braking and ambipolar diffusion in the formation of interstellar cloud cores and protostars
… (the transport of angular momentum by torsional Alfven waves) and ambipolar diffusion (the relative drift between neutral and charged particles). A core forms and ultimately evolves much more rapidly than the surrounding cloud. A core-envelope separation is demonstrated, and the final mass and …
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Numerical Analysis and Theory of Oblique Alfvenic Solitons Observed in the Interplanetary Magnetic Field
… Solitons are weakly nonlinear localized waves that tend to retain their form as they propagate and can be observed in various media which exhibit nonlinear steepening and dispersive effects. This thesis expands the claim that these pulses or bumps are nonlinear oblique Alfven waves with …
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Perpendicular Ion Heating by Low-frequency Alfven-wave Turbulence
… of the proposed models is based on low-frequency Alfven waves (o << O i) launched from the coronal base. Theoretical studies and numerical simulations have shown that Alfven-wave low-beta turbulence primarily cascades to smaller scales perpendicular to the mean magnetic field rather than smaller …
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Numerical simulations of mass outflows from star-forming regions
… of the MHD wave families (in particular shear Alfven waves) stably. Therefore, an extension to the CT algorithm is developed using the method of characteristics (MOC), and it is demonstrated that the resulting hybrid CT/MOC method does provide for the stable evolution of all modes of MHD wave …
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A statistical study of plasmawaves and energetic particles in the outer magnetosphere
… field, and interacting with a variety of waves. The dynamics of energetic particles are often described in terms of three kinds of adiabatic invariants. Energetic electrons are often unstable to the whistler-mode chorus waves, and ions, to the electromagnetic ion cyclotron (EMIC) …
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Non-Linear Magnetosphere-Ionosphere Interactions at High Latitudes
… model describing interaction between dispersive Alfven waves and the nightside high-latitude ionosphere. Results are presented from a numerical study of small-scale, intense magnetic field-aligned currents observed in the vicinity of the discrete auroral arc by the Magnetosphere-Ionosphere …
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Convection and Magnetic Field Generation in Rotating Spherical Fluid Shells
… are also presented. An example are the torsional Alfven waves found in the numerical simulations of this dissertation. They are geophysically relevant as a possible cause for the observed secular variation impulses of the Earth's magnetic field. Reversals of the magnetic field polarity have also …
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A Study of Magnetic Reconnection: From 2D Energy Release to 3D Spreading and Localization
… the X-line (the location of reconnection) at the Alfven speed due to the magnetic tension in the reconnected magnetic field, therefore generating outflows. This dissertation addresses three fundamental properties of magnetic reconnection.;Solar flares are explosive events in the solar corona in …
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Test particle studies of acceleration and transport in solar and tokamak plasmas
… response of protons to cold plasma fast Alfven waves propagating in a non-uniform magnetic field configuration (specifically, a two-dimensional X-point field) is studied. The field perturbations associated with the waves, which are assumed to be azimuthally-symmetric and invariant in the …
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Plasma Heating By Alfven Wave In Field-Reversed Ion Ring Experiment
… with ring ion velocities in excess of the Alfven speed in the plasma, can be violently unstable to generation of compressional Alfven waves with wavelengths short compared to the ring orbit size. Two-dimension, axi-symmetric numerical simulations showed that the momentum transferred to the …
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Dispersive waves in Earth's outer core
… addresses the generation and propagation of waves in Earth's fluid outer core, with the objective of better understanding their role in maintaining our planet's magnetic field. The classes of waves studied, which owe their existence both to the rapid rotation of the Earth about its axis and …