Analytic and numerical calculations of the ambipolar electric field in a stellarator
Abstract
The formula for calculating the radial electric field in a stellarator is usually the steady state ambipolarity relationship. This equation is local in space and when solved with the density rate equations, results in several different electric field solutions. This raises a number of questions: how does the plasma choose the electric field solution, can two spatially close points be on different roots and what limits how fast the plasma can change solution? The time dependent version of the ambipolarity relationship is analyzed in terms of the theory of nonlinear differential equations. It is also shown that the width of the zone over which the solution changes is limited by the orbit deviation from the flux surface. Finally, the equations are solved numerically to illustrate some of these physical concepts.
- Publication:
-
Transport in Open-Ended Systems
- Pub Date:
- March 1985
- Bibcode:
- 1985toes.work..118H
- Keywords:
-
- Ambipolar Diffusion;
- Analysis (Mathematics);
- Electric Fields;
- Flux Density;
- Numerical Analysis;
- Radial Distribution;
- Steady State;
- Stellarators;
- Differential Equations;
- Nonlinear Equations;
- Plasma Physics