ITER Technology and Diagnostics Division (ITED), Max Planck Institute for Plasma Physics (IPP), Garching
and Experimental Plasma Physics (EPP), University of Augsburg
In the focus of both research groups is the development of large negative hydrogen ion sources for the neutral beam heating system of ITER for which two large scale test facilities are in operation within the ITED division supported by fundamental research at small lab-scale experiments at EPP. The experimental activities are accompanied by plasma and beam modelling. The hydrogen and deuterium plasmas are operated at low pressure (0.2 – 20 Pa) and are typical low-temperature plasmas with electron temperatures ranging from about 0.5 eV up to 10 eV and electron densities between 1016 m-3 and 1019 m-3. This allows investigating the ionizing plasma regime as well as the recombining one and the transition.
Since many years, the group is involved in compiling and assessing atomic and molecular data partially in close collaboration with theoreticians and experimentalists providing the data. Special focus is on A&M spectroscopy as it is the main diagnostic tool. Species of particular interest are H, H2 and D2, He, Ar and N2 but also CH, C2, BH and BeH were studied. Where needed and possible, the available data set is extended, for example by Franck Condon factors, transition probabilities for different molecular species and by ionization cross sections for the hydrogen molecule. Within the scope of these activities, the group participated in several past IAEA Coordinated Research Projects (CRPs).
The atomic and molecular data is used as input for population models, mainly Collisional Radiative (CR) models based on the flexible solver Yacora. These models are validated using an extensive set of plasma diagnostics available at the experiments ITED and EPP. All spectroscopic systems are intensity calibrated and cover a wide wavelength range (from about 100 nm to 900 nm). Yacora CR models are available for numerous atomic and molecular species and some of them are accessible via the web application Yacora on the Web.
The extensive experimental and theoretical knowledge present in the group triggered numerous collaborations with other research groups worldwide. The topic is mainly the interpretation of emission spectra; these are taken in experiments as different as linear plasma expansion machines or the scrape-off layer of fusion experiments.
Prof. Dr.-Ing. Ursel FANTZ