Results of the stellarator optimization with respect to the neoclassical 1/ν transport

Powerful tools have been developed in the last years for the design of new stellarator devices. This codes are usually working in magnetic coordinates. Tasks addressed by these codes are minimization of neoclassical transport, maximizing equilibrium and stability properties, etc. However, optimizing existing stellarators is time consuming because costly coordinate transformations are involved. A procedure working in real space coordinates for maximizing the plasma energy content, based on reducing the most unfavorable 1/ν neoclassical transport, has been presented in [1]. This tool, named SORSSA, was developed especially for optimizing existing stellarator devices which are not fully optimized with respect to neoclassical transport. Some results for the stellarators Uragan 2M, U-2M, TJ-II and the Columbia Nonneutral Torus, CNT, are presented. (author)