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Publications in Scientific Journals:

R. Ding, D. Rudakov, P. Stangeby, W. Wampler, T. Abrams, S. Brezinsek, A. Briesemeister, I. Bykov, V. Chan, C. Chrobak, J. Elder, H. Guo, J. Guterl, A. Kirschner, C. Lasnier, A. Leonard, M. Makowski, A. McLean, P. Snyder, D. Thomas, D. Tskhakaya, E. Unterberg, H. Wang, J. Watkins:
"Advances in understanding of high-Z material erosion and re-deposition in low-Z wall environment in DIII-D";
Nuclear Fusion, 57 (2017), 0560161 - 0560168.



English abstract:
Dedicated DIII-D experiments coupled with modeling reveal that the net erosion rate of
high-Z materials, i.e. Mo and W, is strongly affected by carbon concentration in the plasma
and the magnetic pre-sheath properties. Different methods such as electrical biasing and
local gas injection have been investigated to control high-Z material erosion. The net erosion
rate of high-Z materials is significantly reduced due to the high local re-deposition ratio. The
ERO modeling shows that the local re-deposition ratio is mainly controlled by the electric
field and plasma density within the magnetic pre-sheath. The net erosion can be significantly
suppressed by reducing the sheath potential drop. A high carbon impurity concentration in
the background plasma is also found to reduce the net erosion rate of high-Z materials. Both
DIII-D experiments and modeling show that local 13CH4 injection can create a carbon coating
on the metal surface. The profile of 13C deposition provides quantitative information on
radial transport due to E B drift and the cross-field diffusion. The deuterium gas injection
upstream of the W sample can reduce W net erosion rate by plasma perturbation. In H-mode
plasmas, the measured inter-ELM W erosion rates at different radial locations are well
reproduced by ERO modeling taking into account charge-state-resolved carbon ion flux in the
background plasma calculated using the OEDGE code.

Keywords:
erosion, deposition, high-Z materials, impurity

Created from the Publication Database of the Vienna University of Technology.