Speaker
C. Christopher Klepper
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.1017.pdf
Measurement and modeling of tungsten sources in WEST
C.C. Klepper1, O. Meyer2, E.A. Unterberg1, A. Sepetys2 , Y. Marandet3, R. Guirlet2 ,H.
Bufferand2, G. Ciraolo2, J.H. Harris1, P. Lotte2 and the WEST Team
1
Oak Ridge National Laboratory, Oak Ridge, TN 37831-6169, USA†
2
CEA, IRFM, F-13108 Saint Paul Lez Durance, France
3
PIIM, CNRS-Université de Provence, Marseille, France
WEST is the first superconducting tokamak to have begun operations with all tungsten (W)
plasma-facing components (PFCs) [1]. To fully benefit from the opportunity to study W
sources in this all W environment, including the relative contributions from divertor and wall
regions, as well as synergy between them, dedicated experimental sessions are planned for the
upcoming campaigns. In anticipation of these dedicated pulses, relevant measurement and
modeling capabilities are discussed, together with the experimental plan.
For source characterization, all regions of interest are accessible by means of in vessel
periscopic optics and optical fiber assemblies, thus overcoming the direct access limitations
imposed by the cryostat [2]. Two spectrally resolving instruments are supplemented by an
ORNL Filterscope [3] system, to resolve sources at ELM-relevant timescales. This is
necessary, as intra-ELM sources can have a different dependence on plasma parameters than
inter-ELM sources [4], thus also potentially affecting the relative weight between divertor and
wall sources in ELMing H-mode discharges. All optics and instruments are optimized for
transmission and detection at and near the W I line at 400.9nm, while the Filterscope also
includes continuum emission monitoring from a (line free) region spectrally offset from the W
I line, to correct for bremsstrahlung or blackbody radiation. Dα is simultaneously detected.
Spectral filtering is optimized to avoid the parasitic lines from e.g. diagnostic argon
injections. Early spectra and Filterscope commissioning data will be shown and discussed.
Progress in the simulation of W sources from WEST will be also discussed in the context
of interpretation of the spectroscopic data. Earlier studies had revealed the divertor baffle to
be a potentially significant source region outside the divertor targets [5]. Refinements in these
calculations, including the effect of impurities will be presented. Longer term plans, including
long-pulse W migration studies will also be briefly discussed in the context of measurement
and modeling capabilities. [1] J. Bucalossi et al., Fusion Eng. Des. 86 (2011) 684; [2] O. Meyer et al., RSI
87, 11E309 (2016); [3] E.A. Unterberg et al., RSI 83, 10D722 (2012); [4] N. Den Harder et al., NF 56, 026014
(2016)); [5] M. Marandet, JNM 463, p. 629, 2015)
†Work supported, in part, by US DOE under Contract DE-AC05-00OR22725 with UT-Battelle, LLC.
