Design and first measurements of the divertor Thomson scattering system on the ASDEX Upgrade tokamak

Abstract

A new divertor Thomson scattering system was installed on the ASDEX Upgrade tokamak, to measure profiles of electron density and temperature in the lower divertor along a poloidal cord, starting in the outer divertor, crossing the x-point, and ending on the high field side. No direct access to these regions from outside the vacuum vessel is possible. So critical parts of the laser beam line, and the light collection system had to be installed inside the vacuum vessel. Details of the design and first measurements are presented in this article.