Sherwood 2015

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General 3-D stellarator equilibria using the surface current model

Author: Jeff Freidberg
Requested Type: Poster Only
Submitted: 2015-01-17 08:05:24


Contact Info:
NW16-254, 167 Albany St.
Cambridge, MA   02139

Abstract Text:
Our ultimate goal is to calculate the MHD equilibrium and stability of a general 3-D stellarator using the surface current model. The work presented here represents the first stage in this work, namely the formulation of the equilibrium problem. The surface current model is an admittedly highly simplified description of a plasma. The pressure is constant over the entire volume of plasma and the confining currents are assumed to flow solely on the plasma surface – hence the name “surface current model”. In spite of its simplicity, the model provides a crisp, concise, and physically reliable description of both equilibrium and external mode stability; that is, the model accurately captures the basic macroscopic MHD physics. Interestingly, in order to carry out the equilibrium and stability analysis, one need only specify the shape of the 3-D plasma surface (plus the constant values of pressure, external toroidal field, and net toroidal current). Once this information is provided, the analysis presented here demonstrates how the equilibrium magnetic fields on each side of the plasma surface can be calculated. These fields are all that are required to carry out the stability analysis. The end result of the equilibrium analysis is a set of coupled first order, two dimensional, nonlinear partial differential equations in which the basic unknowns are the toroidal and poloidal components of the magnetic field just outside the plasma surface. The equations look innocent enough but are difficult to solve numerically. My challenge to my colleagues with computational expertise is whether they can suggest a clever numerical method for solving these equations in a more convenient way than the brute force method that I currently envisage.

Prefer Monday or Tuesday poster - may have to leave on Wednesday

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