Overview of TJ-II experiment

The construction and assembly of the flexible Heliac TJ-II located at the Centro de Investigaciones Energeticas Medio Ambientales y Tecnologicas (CIEMAT), Madrid, has recently been finished. The problems encountered during manufacturing this strongly helical machine have been solved satisfactory. Nevertheless the complicated geometry, the low magnetic permeability of all materials and the required narrow tolerances, created real challenges for all the component manufactures. First measurements of the magnetic surfaces in the device have been done, using the fluorescent rod technique at electron energies between 100 and 200 eV. A very good agreement has being found between magnetic surface measurements and theoretical predictions. Plasma operation with 1 MW, 53.2 Ghz, ECH system is about to start. (author)