ERO modelling of Be erosion and light emission at JET ILW

1. ERO modelling of Be erosion and light emission at JET ILW D.Borodin1, M.Stamp, A.Kirschner1, C.Björkas1,2, S.Brezinsek1, J.Miettunen3, D.Matveev1, O. Van Hoey5, M.Groth3, C.Silva4, S.Marsen6, M.Airila2, V.Philipps1 and JET EFDA contributors* JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB, UK 1Institute of Energy and Climate Research - Plasma Physics, Forschungszentrum Jülich GmbH, Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, Jülich, Germany 2EURATOM-Tekes, Department of Physics, P.O. Box 43, FI-00014 University of Helsinki, Finland 3Aalto University, EURATOM-Tekes, Espoo, Finland 4Associação Euratom/IST, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Lisbon, Portugal 5Department of Applied Physics, Ghent University, Rozier 44, 9000 Ghent, Belgium 6Max-Planck-Institut for Plasma Physics, EURATOM Association, Greifswald, Germany * See the Appendix of F. Romanelli et al., Fusion Energy 2010 (Proc. 23rd Int. FEC Daejeon, 2010) IAEA, (2010) P1-81 Contact: d.borodin@fz-juelich.de ABSTRACT This paper presents the first attempt to reproduce by modelling using the 3D Monte-Carlo ERO code the spectroscopic observations of beryllium (Be) species spectroscopy [1] in the vicinity if the massive Be limiter, a part of JET ITER-like wall. The observed dependence of line intensities on plasma parameters during the density scan are used to validate the model and the underlying data including the recently introduced assumptions for Be physical sputtering, which were used previously for ITER predictive modelling [2]. • EXPERIMENTAL GEOMETRY AND PLASMA PARAMETERS • Plasma parameters mapped[6] from reciprocation probe [7] measurements for 2D poloidal plane using 2-point model and rotated in toroidal direction assuming respective symmetry. MOTIVATION AND UNDERLYING THEORY The main aim is to benchmark physical erosion model in ERO and the underlying data  minimal and maximal estimates in the form of recent Eckstein’s fit [2] were derived Eckstein 2007 fit: Y = Y(Ein, 0o) * A(Ein,αin) a) Poloidal position of the Be limiter tile. b) 3D limiter shape and line of sight inside the ERO simulation box. c) Poloidal cross-section of electron temperature d), e) Poloidal and toroidal cross-section of electron density. ERO SIMULATION RESULTS small density • ISSUES FOR ITER: • Erosion determines the inner wall life time • ERO simulations [1] predict 1100-4200 ITER shots for “ERO-min” - ”ERO-max” margins • Tritium retention is influenced by erosion and re deposition 3D MC impurity transport and PSI ERO code small density Large density Large density Large density Be transport simulated by ERO (2D light emission pattern – toroidal view) Erosion patterns simulated by ERO Be erosion pattern simulated using averaged yields based on pre-calculated impact statistics • CONCLUSIONS and IMPLICATIONS FOR ITER • The 3D ERO code was for the first time applied to the spectroscopic experiments with Be species eroded from the solid shaped limiter of JET ILW during the plasma density scan. • The simulations can qualitatively reproduce BeII intensity trend during plasma density scan. However, at the current stage, uncertainties e.g. in the plasma parameters (ERO input) does not allow to reproduce the absolute values, thus can’t be used for judgment about physical erosion data. • This work demonstrates principal possibility of erosion data benchmark in the described way and modelling necessity for correct interpretation of experiment. • NEXT STEPS... • Improved experimental data • Absolute calibration • Larger plasma parameter scan and additional measurements • Improved modelling • Proper simulation of the background plasma (SOLPS) • Intrinsic Be impurity (self sputtering) • Be-D molecules release and transport [5] • Enhanced re-erosion, metastable tracking, gaps, … • Benchmark of ERO by 10Be marker experiment [6] at JET ILW Zeff used for a crude estimation of Be plasma impurity increasing erosion due to self-sputtering Total light inside the spot simulated by ERO and measured during density scan ACKNOWLEDGEMENTS This work was supported by EURATOM and carried out within the framework of the European Fusion Development Agreement. The views and opinions expressed herein do not necessarily reflect those of the European Commission. REFERENCES [1] D.Borodin et al., Phys. Scr. T145 (2011) 014008 [2] W. Eckstein (2007) Topics in Applied Physics, 110, pp. 33-187; doi: 10.1007/978-3-540-44502-9-3 [3] Summers HP, 2004 The ADAS User Manual version 2.6; http://adas.phys.strath.ac.uk [4] C.Björkas et. al, this conference [5] J.Miettunen et. al, this conference [6] C.Silva et. al, this conference