Metrology support of flux surface diagnostic installation

Magnetic flux surface measurements are the first diagnostic activities at Wendelstein 7-X (W7-X). At present, two out of three flux surface measurement diagnostics are installed. The paper presents the metrology methods used during assembly of the diagnostics, starting with assembly of hosting ports, assembly of diagnostic and the final position measurements. It is shown on the example of two corresponding ports that their axis can be aligned very precisely to a common plane within deviations less than 1mm in the volume of the vacuum vessel (VV). The methods of determination the sweeping plane of a long, flexible fluorescent rod and of the direction of the electron-gun(e-gun) are described. It is shown that the as-built sweeping plane as well as the as-built e-gun direction fit very well to the design. The uncertainties of VV-intern measurements and the uncertainties w.r.t. to the global W7-X reference point net, fixed on the walls of the experimental hall, are given and discussed. It is shown that the main part of uncertainties (approx. 1mm) results from deformations of the VV-intern reference point net, appeared after co-ordinate transfer into VV.