René Reimer, Andreas Dinklage, Robert Wolf, Mike Dunne, Benedikt Geiger, Jörg Hobirk, Matthias Reich, ASDEX Upgrade Team and Patrick J. Mc Carthy

2017

April

Nuclear Fusion

Investigation of fast ion pressure effects in ASDEX Upgrade by spectral MSE measurements

Published

WOS: 8 ()

motional Stark effect, combined Zeeman and motional stark effect, beam emission spectroscopy, magnetic field measurements, magnetically confined plasmas, plasma diamagnetism, fast ions in tokamaks

57

4

046005

High precision measurements of fast ion effects on the magnetic equilibrium in the ASDEX Upgrade tokamak have been conducted in a high-power (10 MW) neutral-beam injection discharge. An improved analysis of the spectral motional Stark effect data based on forward-modeling, including the Zeeman effect, fine-structure and non-statistical sub-level distribution, revealed changes in the order of 1% in B. The results were found to be consistent with results from the equilibrium solver CLISTE. The measurements allowed us to derive the fast ion pressure fraction to be $ \Delta {{p}_{\text{FI}}}/{{p}_{\text{mhd}}}\approx 10 \% $ and variations of the fast ion pressure are consistent with calculations of the transport code TRANSP. The results advance the understanding of fast ion confinement and magneto-hydrodynamic stability in the presence of fast ions.

10.1088/1741-4326/aa5877