Sherwood 2015

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approvedpoloidal_viscosity_sherwood_2015_tex.latex2015-01-19 09:39:42Luca Guazzotto

Extension of Physics of the MHD Pedestal Formation

Author: Luca Guazzotto
Requested Type: Poster Only
Submitted: 2015-01-19 09:37:49

Co-authors: R. Betti

Contact Info:
Auburn University
206 Allison Lab
Auburn, AL   36849

Abstract Text:
Finite toroidal and poloidal flows are routinely observed in the edge plasma region of tokamak experiments. MHD theory predicts that when the poloidal velocity is transonic with respect to the poloidal sound speed (csp ≡ cs Bp/B, where Bp is the poloidal field) a transient will develop. After the end of the transient, a steady-state MHD pedestal in plasma density and pressure is left, with the height of the pedestal depending on the poloidal location. The formation of the MHD pedestal was demonstrated with time-dependent simulations with the resistive-MHD code SIM2D. In the present work, we explore the effect of additional physics on the properties of the transonic discontinuity, focusing in particular on poloidal viscosity. Analytic expressions are used for the poloidal viscosity and applied to fast rotating plasmas of increasing complexity, from one-dimensional equilibrium models to numerical solutions of the transonic equilibrium problems to snapshots of the time-dependent evolution of plasmas with poloidal momentum sources. Results are used to compare the power dissipated by viscosity with the input power and to obtain an estimate of the accuracy of the MHD model for the problem under investigation. Work supported by US Department of Energy Contract No. DE-FG02-93ER54215.


March 16-18, 2015
The Courant Institute, New York University