Electron density measurements in detached divertor plasmas of ASDEX Upgrade via Stark broadening Of the Balmer lines

摘要

In ITER, in order to be able to handle the particle and power fluxes to the target material, the divertor has to be operated with the plasma detached or semi-detached from the target. Thus, understanding the physics of detachment is crucial to make predictions for the ITER divertor. In the detached regime, the region of high electron density (n_e) is retracted from the target and the commonly used Langmuir probes, do not provide information about the plasma in the divertor volume. In this context, a new spectroscopic method has been developed to determine n_e in the divertor of ASDEX Upgrade, using the Stark broadening of the Balmer lines. After introducing this method, measurements of a detached divertor plasma are presented. Finally, it is shown how impurity seeding can change the detached divertor plasma.