1. Introduction. - 2. Synopsis of the Method. - 1. Variational principle. - 2. Coordinate system. - 3. Finite Difference Scheme. - 1. Difference equations. - 2. Island structure. - 3. Accelerated iteration procedure. - 4. Nonlinear Stability. - 1. Second minimization. - 2. Test functions and convergence studies. - 3. Comparison with exact solutions. - 5. The Mercier Criterion. - 1. Local mode analysis. - 2. Computational method. - 3. Island width and anomalous diffusion. - 6. Transport. - 1. Classical and neoclassical models. - 2. Flux coordinates. - 7. Stellarator Experiments. - 1. The mathematical model. - 2. The Heliotron E. - 3. The Wendelstein W VII-A. - 8. The ATF-1 and the WISTOR-U. - 1. Helical coil winding laws. - 2. Beta limits for the ATF-1. - 9. Heliac. - 1. Helically symmetric equilibria. - 2. Stability. - 3. Free boundary equilibria. - 10. References. - 11. Description of the Computer Code BETA. - 1. Introduction. - 2. Geometry. - 3. Initialization. - 4. Grids. - 5. Convergence. - 6. Stability. - 7. Iteration. - 8. Vacuum region. - 9. Printed output. - 10. Plots. - 12. Glossary. - 13. Sample Run. - 14. Listing of Code BETA with Comment Cards. Language: English