Speaker
Marco Valisa
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.1096.pdf
On the penetration of heavy impurities in the JET ELMy H-mode plasmas
M. Valisa1, L. Carraro1 F. J. Casson2, J Citrin3, L. Frassinetti4, F. Koechl2, M.Romanelli2 M.
E. Puiatti1, I. Coffey5, E Delabie6, C. Giroud2, A. Loarte7, S. Menmuir2, M. O’Mullane8, M.
Sertoli2 and JET contributors*
EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, UK
1 2
Consorzio RFX, Padova, Italy, CCFE, Culham Science Centre, Abingdon, OX14 3DB, UK,
3 4
FOM Inst. Differ NL, KTH, Royal Institute of Technology, Sweden
5 6
Queen’s University, Belfast, UK, ORNL Oak Ridge US
7
ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance, France
8
Department of Physics SUPA, University of Strathclyde, Glasgow, G4 ONG, UK
E-mail contact of main author: valisa@igi.cnr.it
This paper reports the main outcomes of the recent modeling activities in which the way the
penetration of medium and high Z impurities into the plasma core of JET evolves with ELM
frequency and heating power has been investigated. The motivation was to assess and to pro-
vide physics basis for the ELM-control requirements in ITER.
Modeling has focused on the simulation of experiments in which traces of Ne have been
puffed in ELMy H-mode plasmas with medium (12 MW) and high (32 MW) NBI power in-
jection and in which the ELM frequency was varied by controlling the main gas fueling.
The main experimental evidences investigated by means of the simulation are the inverse
proportionality between the concentration of any impurities and the ELM frequency, and the
ELM-resolved time evolution of the Ne density at the edge as provided by charge exchange
measurements [1]. In addition, the effect of increasing heating power has been studied: as the
heating power is increased, the edge kinetic profiles change in the direction of reducing the
neoclassical inward velocity of impurities and therefore in the direction of the situation ex-
pected in ITER, where heavy impurities should be repelled at the H mode barrier by a favora-
ble combination of density and ion temperature profiles.
Full predictive modeling includes simulations by means of JETTO-SANCO with three impu-
rities (Be, Ne, W) and integrated JETTO-SANCO-Edge2D with two impurities (Ne, W), both
available in the JINTRAC suite of codes [2].
Turbulent transport in the core is simulated by means of QualiKiz [3] or GLF23 [4]. In simple
cases the BgB model multiplied by a suitable factor has been used. While waiting for the in-
put from physics based models such as JOREK [5], for the ELM description we have assumed
a heuristic model with either ad hoc enhancements of heat and particle diffusivities in the bar-
rier region or an ad hoc burst of the outward radial velocity. In this way the impact of convec-
tive versus diffusive transport during an ELM event has also been investigated. Analogously,
transport in the barrier region outside the ELM event is also described heuristically imposing
neoclassical transport and an ad hoc turbulent transport multiplier.
[1] Valisa M et al Proc. 44th EPS Conf.2017 http://ocs.ciemat.es/EPS2017PAP/pdf/P4.174.pdf
[2] Romanelli M et al Plasma Fusion Res. 9, 3403023 [3] Bourdelle C et al Phys Pl. 14 112501(2017)
[4] Waltz RE & Miller RL Phys Plasmas 6 4265 1999
[5] Hujsmans GTA & Czarny _Nucl .Fus 47 659 (2007)
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*See the author list of “X. Litaudon et al. Nucl. Fusion 2017 57 102001”
