University of Opole
Emission spectroscopy and diagnostics of impurities in a MCF plasma (EUROFusion) Our group participates both in tokamak and stellarator experiments (mostly JET and W7X), measuring and analyzing spectra from XUV, VUV and UV/Vis/IR regions. We are interested in both atomic (in visible or VUV – Ar, Be, Ni, W) and molecular spectra (H2, D2, hydrids: BeH to BeT, ND and so on). We use it for impurity density estimation, electron temperature and density estimation, and plasma-surface reaction studies.
We use two methods in our calculations:
Well known method based on impact and quasi-static approximation for electrons and ions, respectively. It provides the so-called j(x) profiles developed by Griem.
Computer simulation methods (CSM) Through calculations, motion of a statistically representative number of perturbers is modeled. The resulting electric-field history, as experienced by the emitters, are used to obtain time evolution of the latter, allowing for obtaining the emitter spectrum. Such calculations are believed to be the most reliable type of Stark broadening models because they are based on a very few approximations, in contrast to the j(x) profiles. Moreover, unlike the impact theory, weak and strong collisions are treated identically. CSM was originally developed to describe the so-called ion dynamic effect for hydrogen spectral lines, however, for emitters heavier than hydrogen, e.g. atomic argon, this effect plays almost no role and the contribution of ions to the linewidth is much smaller than the electrons, in general.
Instytut Fizyki Uniwersytetu Opolskiego, ul. Oleska 48, 45-052 Opole, Poland