Author: Michael SchittenhelmPublisher:
ISBN:
Category :
Languages : en
Pages : 101
Book Description
Investigation of Tearing Modes in Asymmetric Elongated Plasmas in the ASDEX Upgrade Tokamak
Author: Michael SchittenhelmPublisher:
ISBN:
Category :
Languages : en
Pages : 101
Book Description
Investigation of tearing modes in asymmetric elongated plasmasin the ASDEX upgrade tokamak
Author: M. SchittenhelmTearing Mode Dynamics in Tokamak Plasmhb
Author: FITZPATRICKPublisher: IOP Series in Plasma Physics
ISBN: 9780750353656
Category :
Languages : en
Pages : 0
Book Description
This comprehensive research and reference text aims to outline a realistic, comprehensive, self-consistent, analytic theory of tearing mode dynamics in tokamak plasmas.
Influence of Plasma Rotation on Tearing Mode Stability on the ASDEX Upgrade Tokamak
Author: Sina Marie Ariane FietzPublisher:
ISBN:
Category :
Languages : en
Pages : 104
Book Description
A Study of Tearing Modes Via Electron Cyclotron Emission from Tokamak Plasmas
Author: Chuang RenTearing Mode Dynamics in Tokamak Plasmas
Author: Nikolaos VergosPublisher:
ISBN:
Category :
Languages : en
Pages : 352
Book Description
One of the most problematic instabilities in tokamak plasmas is tearing modes; they are driven by current and pressure gradients, and involve a reconfiguration of the magnetic and velocity fields localized into a narrow region located at a resonant magnetic surface. While the equilibrium magnetic field lines are located on concentric nested toroidal flux surfaces, the instability creates magnetic islands in which field lines connect flux tubes together, allowing for a high radial heat transport, and, thus, resulting in a loss of confinement, and, potentially, disruptions. In order for the magnetic field lines to break and reconnect, we need to take into account the resistivity of the plasma and solve the resistive magnetohydrodynamics (MHD) equations. The analytical solution consists of a boundary layer analysis (asymptotic matching) and takes advantage of the small radial width of the region where the perturbations vary significantly. Indeed, ideal magnetohydrodynamics can be used everywhere except in that narrow region where the full resistive problem must be solved. This dissertation addresses two related problems in the study of resistive tearing modes, and their interactions with externally induced resonant magnetic perturbations (error-fields). First, an in-depth investigation of the bifurcated states of a rotating, quasi-cylindrical, tokamak plasma in the presence of a resonant error-field is performed, within the context of constant-[greek letter psi] resistive MHD theory. The response of the rotating plasma is studied in both the linear, and the nonlinear regime. In general, there is a "forbidden band" of tearing mode rotation frequencies that separates a branch of high-frequency solutions from a branch of low-frequency solutions. When a high-frequency solution crosses the upper boundary of the forbidden band there is a bifurcation to a low-frequency solution, and vice versa. Second, the analysis is extended to include the study of braking and locking of tearing mode rotation by the interaction of the mode with an error-field. It is found that this interaction can brake the plasma rotation, suppress magnetic island evolution and drive locked modes.
Euro Abstracts
Author: Experimental Studies and Modeling of Divertor Plasma Detachment in H-Mode Discharges in the ASDEX Upgrade Tokamak
Author: Felix ReimoldINIS Atomindex
Author: A Study of Tearing Modes Via Electron Cyclotron Emission from Tokamak Plasmas
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 79
Book Description
This thesis studies several tearing mode problems from both theoretical and experimental points of view. A major part of this thesis is to demonstrate that Electron Cyclotron Emission (ECE) is an excellent diagnostic for studying an MHD mode structure and its properties in a tokamak plasma. It is shown that an MHD mode can be detected from the electron temperature fluctuations measured by ECE. The amplitude and phase profiles of the fluctuations contain detailed information about the mode structure. The ECE fluctuation phase profile indicates the magnetic island deformation due to the combination of sheared flow and viscosity. A model is presented to relate qualitatively the observed phase gradient to the local magnetic field, flow velocity shear and viscosity in a 2D slab geometry, using an ideal Ohm's law and the plasma momentum equation including flow and viscosity. Numerical solution of the resultant Grad-Shafranov-like equation describing the deformed island shows that the experimentally observed value of the phase gradient can be obtained under realistic parameters for the shear in the flow velocity and viscosity. A new approach to the tearing mode stability boundary and saturation level is also presented.