Bremen 2017 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 28: Helmholtz Graduate School III
P 28.3: Vortrag
Donnerstag, 16. März 2017, 14:50–15:15, HS 1010
Line ratio spectroscopy on thermal helium provides electron temperature and density information at the plasma edge of ASDEX Upgrade — •Michael Griener1,2, Elisabeth Wolfrum1, Jorge Muños Burgos3, Oliver Schmitz4, Ulrich Stroth1,2, and the ASDEX Upgrade Team1 — 1Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany — 2Physik Department E28, TUM, Garching — 3Department of Physics & Astronomy, Johns Hopkins University, Baltimore, USA — 4Engineering Physics Department, University of Wisconsin-Madison
In magnetically confined fusion devices large power fluxes cross the last closed flux surface. The local power deposited on the first wall depends strongly on the transport perpendicular to the magnetic field lines. It can be dominated e.g. by filamentary structures or turbulence.
To investigate steady-state as well as fast transport processes, a thermal helium beam has been implemented as plasma edge diagnostic at the ASDEX Upgrade experiment. Helium emission intensity ratios of two singlet lines combined with a collisional radiative model (CRM) enable the reconstruction of electron density values, whereas singlet-triplet ratios provide the electron temperature.
In this talk, the physical principle as well as the hardware components of the He-diagnostic will be presented. The measured absolute emission intensity profiles of several He I transitions are compared to the calculated values of two CRMs. One is based on equilibrium assumptions, the other models the time evolution of the two spin systems. This influence on the resulting ne and Te profiles is discussed.