Author: Yasutaro NishimuraPublisher:
ISBN:
Category :
Languages : en
Pages : 292
Book Description
Finite Pressure Effects on the Tokamak Sawtooth Crash
Author: Yasutaro NishimuraFinite Pressure Effects on the Tokamak Sawtooth Crash
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 141
Book Description
The sawtooth crash is a hazardous, disruptive phenomenon that is observed in tokamaks whenever the safety factor at the magnetic axis is below unity. Recently, Tokamak Test Fusion Reactor (TFTR) experimental data has revealed interesting features of the dynamical pressure evolution during the crash phase. Motivated by the experimental results, this dissertation focuses on theoretical modeling of the finite pressure effects on the nonlinear stage of the sawtooth crash. The crash phase has been studied numerically employed a toroidal magnetohydrodynamic (MHD) initial value code deduced from the FAR code. For the first time, by starting from a concentric equilibrium, it has been shown that the evolution through an m/n = 1/1 magnetic island induces secondary high-n ballooning instabilities. The magnetic island evolution gives rise to convection of the pressure inside the inversion radius and builds up a steep pressure gradient across the island separatrix, or current sheet, and thereby triggers ballooning instabilities below the threshold for the axisymmetric equilibrium. Due to the onset of secondary ballooning modes, concomitant fine scale vortices and magnetic stochasticity are generated. These effects produce strong flows across the current sheet, and thereby significant modify the m = 1 driven magnetic reconnection process. The resultant interaction of the high-n ballooning modes with the magnetic reconnection process is discussed.
Finite Pressure Effects on Sawtooth Oscillation
Author: Wonchull ParkUniversity of Wisconsin Center for Plasma Theory and Computation Report
Author: Publisher:
ISBN:
Category : Plasma (Ionized gases)
Languages : en
Pages : 336
Book Description
Dissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 892
Book Description
Energy Research Abstracts
Author: American Doctoral Dissertations
Author: Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 784
Book Description
Physics Briefs
Author: Scientific and Technical Aerospace Reports
Author: Magnetic Field Line Behavior During a Tokamak Sawtooth Crash
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The tokamak sawtooth crash phase has been studied numerically using the toroidal magnetohydrodynamic initial value code FAR. A magnetic field line solver with high spatial resolution has been developed and incorporated. Global stochasticity has been observed during the nonlinear evolution of m/n= 1/1 resistive internal kink modes. The magnetic field line stochasticity is evaluated quantitatively by calculating Lyapunov exponents as well as spatial correlations of the field lines. The study is extended to explore thermal transport along stochastic magnetic field lines by comparing the pressure structure evolution with the microscopic combined structure of the regular and destroyed magnetic flux surfaces, and by inferring the effective perpendicular thermal diffusivity in the stochastic field regions.