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1 ITC-22, November 2012, Toki, Japan 1 Modelling of impurity transport, erosion and redeposition in fusion devices: applications of the ERO code A. Kirschner.

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Presentation on theme: "1 ITC-22, November 2012, Toki, Japan 1 Modelling of impurity transport, erosion and redeposition in fusion devices: applications of the ERO code A. Kirschner."— Presentation transcript:

1 1 ITC-22, November 2012, Toki, Japan 1 Modelling of impurity transport, erosion and redeposition in fusion devices: applications of the ERO code A. Kirschner 1, D. Matveev 1,2, P. Wienhold 1, D. Borodin 1, C. Björkas 1,3, S. Brezinsek 1, M. Groth 4, K. Krieger 5, U. Samm 1 and JET-EFDA contributors 1 Institute of Energy and Climate Research – Plasma Physics, Research Center Jülich, Germany 2 Department of Applied Physics, Gent University, Belgium 3 Department of Physics, University of Helsinki, Finland 4 Aalto University, Association EURATOM-Tekes, Espoo, Finland 5 Max-Planck-Institut für Plasmaphysik, EURATOM Association, 85748 Garching, Germany

2 2 ITC-22, November 2012, Toki, Japan 2 Outline ● Introduction: ERO modelling ● 13 CH 4 injection in the SOL of TEXTOR ● Impurity transport in the inner JET divertor ● Summary

3 3 ITC-22, November 2012, Toki, Japan 3 ERO modelling: strategy Code development: - PSI & transport - material mixing - castellated surfaces - atomic data, ADAS Benchmarking: - PISCES-B (with beryllium) - TEXTOR, JULE-PSI, … - JET, AUG, W7-X, … - Code-code benchmarking (e.g. EDDY) Estimations (ITER, DEMO): - tritium retention - target, limiter, wall lifetime - impurities into plasma Coupling with other codes: - plasma parameters from: e.g. B2-Eirene, Edge-2D, EMC3 -surface mixing: SDTrimSP, MolDyn

4 4 ITC-22, November 2012, Toki, Japan 4 ionisation, dissociation (Monte-Carlo) friction (Fokker-Planck), thermal force Lorentz force in E, B field cross-field diffusion physical sputtering, reflection chemical erosion (CD 4, BeD) (re-)erosion and (re-)deposition coupling with SDTrimSP Local impurity transport: Plasma-surface interaction (PSI): Background Plasma D,C, … C, … CD 4 C x+,… CD z 0,+ re-eroded/ reflected particles PFC (substrate C, W, Be, …) Input: n e, T e,i, geometry injected ERO modelling: the code

5 5 ITC-22, November 2012, Toki, Japan 5 13 CH 4 injection in TEXTOR

6 6 ITC-22, November 2012, Toki, Japan 6 13 CH 4 injection in TEXTOR Recent experiments: 13 C deposition efficiencies Reduced injection rate: 0.7% (1e18 instead of 1e19 13 CH 4 /s) Biased test limiter: 1.7% (300V instead of floating) Biasing and reduced injection rate increases 13 C deposition efficiency (compared to “reference” conditions: 0.3% ) polished C surface polished C surface A. Kirschner et al. PSI 2012

7 7 ITC-22, November 2012, Toki, Japan 7 ERO modelling: Using “standard” assumptions:- Reflection for atoms according to TRIM - Reflection of CH x : R ion =0.1, R N =1 - No enhanced re-erosion of re-deposits 13 C deposition efficiency ERO / Experiment EROExperiment Reference case 55%0.3%~180 Biased test limiter 42%1.7%~25 Reduced injection rate 34%0.7%~50 13 CH 4 injection in TEXTOR

8 8 ITC-22, November 2012, Toki, Japan 8 ERO modelling: enhanced re-erosion of re-deposits Reduced injection: f_enh ~ 10-15 Reference case: f_enh ~ 35 13 CH 4 injection in TEXTOR

9 9 ITC-22, November 2012, Toki, Japan 9 ERO modelling w/o enhanced re-erosion: influence of injection rate At certain (small, ~1e17 /s) injection rate: no enhanced re-erosion necessary in ERO to match experiment? 13 CH 4 injection in TEXTOR

10 10 ITC-22, November 2012, Toki, Japan 10 Impurity transport in the inner JET divertor

11 11 ITC-22, November 2012, Toki, Japan 11 Impurity transport in the inner JET divertor position of strike point on s-coordinate (m) A B H.G. Esser et al., PSI 2008 Group A: SP on tile 3 Group B: SP on tile 4 Deposition/erosion measurement below LBSRP with QMB: - restart 2006 - JET with carbon wall QMB 1 3 4 5 6 7 8

12 12 ITC-22, November 2012, Toki, Japan 12 Impurity transport in the inner JET divertor Group A - SP on tile 3:deposition on QMB Group B - SP on tile 4:erosion on QMB Deposition/erosion measurement below LBSRP with QMB: - restart 2006 -

13 13 ITC-22, November 2012, Toki, Japan 13 Impurity transport in the inner JET divertor Modelling with ERO: plasma parameter No plasma parameter measurement available for restart: Langmuir probe data from #68126 (Be migration studies in L-mode) SP on tile 3 SOL (mm) PFR (mm) TeTe 16060  3530 nene 40 Decay lengths  exponential fits ne = Te ⋅  / ( Te -0.5  

14 14 ITC-22, November 2012, Toki, Japan 14 Impurity transport in the inner JET divertor Modelling with ERO: plasma parameter Input:- Strike point (SP) position - Angle of separatrix  Sep : 55° - T e, T i, n e within separatrix: 10eV, 15eV, 1e13cm -3 - Exponential decay perpendicular to separatrix, T and n Separatrix SP  Sep SOL PFR Further assumptions: - const B field - v Flow = c S (T e,T i ) - grad T as input z (mm) x (mm)

15 15 ITC-22, November 2012, Toki, Japan 15 Impurity transport in the inner JET divertor Example: plasma parameter along tiles, SP on vertical tile SOL PFR

16 16 ITC-22, November 2012, Toki, Japan 16 NO ENHANCED RE-EROSION OF REDEPOSITS

17 17 ITC-22, November 2012, Toki, Japan 17 Impurity transport in the inner JET divertor Modelling with ERO: SP on vertical tile, physical sputtering NO ENHANCED RE-EROSION Spatial distribution of carbon 3 4 x (mm) z (mm) C 0 density 3 4 x (mm) z (mm) C + density

18 18 ITC-22, November 2012, Toki, Japan 18 Impurity transport in the inner JET divertor Erosion and redeposition along tiles 54% redeposition vertical tile #3 horizontal tile #4 Modelling with ERO: SP on vertical tile, physical sputtering NO ENHANCED RE-EROSION

19 19 ITC-22, November 2012, Toki, Japan 19 Impurity transport in the inner JET divertor Mean energy and charge of redeposited particles vertical tile #3 horizontal tile #4 Modelling with ERO: SP on vertical tile, physical sputtering NO ENHANCED RE-EROSION

20 20 ITC-22, November 2012, Toki, Japan 20 Impurity transport in the inner JET divertor Modelling with ERO: SP on vertical tile, chem. sputtering Y CD4 =1% NO ENHANCED RE-EROSION Spatial distribution of CD 4 and CD 3 4 x (mm) z (mm) CD 4 density 3 4 x (mm) z (mm) CD density

21 21 ITC-22, November 2012, Toki, Japan 21 Impurity transport in the inner JET divertor Spatial distribution of C 0 and C + Modelling with ERO: SP on vertical tile, chem. sputtering Y CD4 =1% NO ENHANCED RE-EROSION 3 4 x (mm) z (mm) C 0 density 3 4 x (mm) z (mm) C + density

22 22 ITC-22, November 2012, Toki, Japan 22 Impurity transport in the inner JET divertor Erosion and redeposition along tiles 63% redeposition vertical tile #3 horizontal tile #4 Modelling with ERO: SP on vertical tile, chem. sputtering Y CD4 =1% NO ENHANCED RE-EROSION

23 23 ITC-22, November 2012, Toki, Japan 23 Impurity transport in the inner JET divertor Mean energy and charge of redeposited particles vertical tile #3 horizontal tile #4 Modelling with ERO: SP on vertical tile, chem. sputtering Y CD4 =1% NO ENHANCED RE-EROSION

24 24 ITC-22, November 2012, Toki, Japan 24 Impurity transport in the inner JET divertor Modelling with ERO: SP on horizont. tile, physical sputtering NO ENHANCED RE-EROSION Spatial distribution of carbon 3 4 x (mm) z (mm) C 0 density 3 4 x (mm) z (mm) C + density

25 25 ITC-22, November 2012, Toki, Japan 25 Impurity transport in the inner JET divertor Erosion and redeposition along tiles 47% redeposition vertical tile #3 horizontal tile #4 Modelling with ERO: SP on horizont. tile, physical sputtering NO ENHANCED RE-EROSION

26 26 ITC-22, November 2012, Toki, Japan 26 Impurity transport in the inner JET divertor Modelling with ERO: SP on horizont. tile, chem. sputt. Y CD4 =1% NO ENHANCED RE-EROSION Spatial distribution of CD 4 and C 0 3 4 x (mm) z (mm) C 0 density 3 4 x (mm) z (mm) CD 4 density

27 27 ITC-22, November 2012, Toki, Japan 27 Impurity transport in the inner JET divertor Erosion and redeposition along tiles 61% redeposition vertical tile #3 horizontal tile #4 Modelling with ERO: SP on horizont. tile, chem. sputt. Y CD4 =1% NO ENHANCED RE-EROSION

28 28 ITC-22, November 2012, Toki, Japan 28 Impurity transport in the inner JET divertor Modelling with ERO: particles entering QMB aperture NO ENHANCED RE-EROSION D + fluence (1/cm · s) C particles to QMB aperture (1/s) Y C/D+ (ERO)Y C/D+ (EXP) SP on vertical, phys. sputtering 2.9x10 19 2.8x10 16 +3.0x10 -3 +2.4x10 -5 SP on vertical, chem. sputtering 6.0x10 16 SP on horizontal, phys. sputtering 2.6x10 19 3.0x10 15 +8.9x10 -4 -0.9x10 -5 SP on horizontal, chem. sputtering 2.0x10 16

29 29 ITC-22, November 2012, Toki, Japan 29 WITH ENHANCED RE-EROSION OF REDEPOSITS - factor 10 for physical and chemical sputtering -

30 30 ITC-22, November 2012, Toki, Japan 30 Impurity transport in the inner JET divertor Modelling with ERO: SP on vertical tile, phys. & chem. sputtering WITH ENHANCED RE-EROSION 61% redeposition vertical tile #3 horizontal tile #4 Erosion ~2 times larger than for case without enhanced re-erosion

31 31 ITC-22, November 2012, Toki, Japan 31 Modelling with ERO:SP on horizont. tile, phys. & chem. sputtering WITH ENHANCED RE-EROSION vertical tile #3 horizontal tile #4 58% redeposition Erosion ~2 times larger than for case without enhanced re-erosion Impurity transport in the inner JET divertor

32 32 ITC-22, November 2012, Toki, Japan 32 Impurity transport in the inner JET divertor Summary: particles entering QMB aperture vs. measured deposition on QMB ●Enhanced re-erosion (factor 10) increases C flux to QMB aperture by factor ~2 ●Deposition/erosion on QMB: detailed transportsimulations inside QMB housing necessary Y C/D+ (ERO)Y C/D+ (EXP) Strike Point on vertical target No enhanced re-erosion+3.0x10 -3 +2.4x10 -5 With enhanced re-erosion+6.6x10 -3 Strike Point on horizontal target No enhanced re-erosion+8.9x10 -4 -0.9x10 -5 With enhanced re-erosion+1.7x10 -3

33 33 ITC-22, November 2012, Toki, Japan 33 QMB located in a “gap-like” structure → Modelling with 3D-GAPS code radial view from inner target Impurity transport in the inner JET divertor

34 34 ITC-22, November 2012, Toki, Japan 34 Annotation: the 3D-GAPS code Modelling of layer deposition in gaps and remote areas PIC simulations: plasma penetration into gap as input for 3D-GAPS

35 35 ITC-22, November 2012, Toki, Japan 35 3D-GAPS modelling: input from ERO Species and velocity distribution of particles entering QMB aperture Only neutral species enter the QMB aperture Impurity transport in the inner JET divertor

36 36 ITC-22, November 2012, Toki, Japan 36 Impurity transport in the inner JET divertor 3D-GAPS modelling: deposition/erosion on QMB No enhanced re-erosion in ERO case A – SP at tile 3 (vertical) case B – SP at tile 4 (horizontal) Agreement with measurement: case A: Y chem =1% (5%) and  D0 ~1 · 10 18 (2 · 10 17 ) cm -2 s -1 case B: Y chem =1% (5%) and  D0 ~1·10 18 (2·10 17 ) cm -2 s -1 erosion/deposition yield

37 37 ITC-22, November 2012, Toki, Japan 37 Impurity transport in the inner JET divertor 3D-GAPS modelling: deposition/erosion on QMB With enhanced re-erosion in ERO Agreement with measurement: case A: Y chem =1% (5%) and  D0 ~3 · 10 18 (1 · 10 18 ) cm -2 s -1 case B: Y chem =1% (5%) and  D0 ~2·10 18 (3·10 17 ) cm -2 s -1 erosion/deposition yield

38 38 ITC-22, November 2012, Toki, Japan 38 ●Modelling of injection experiments in TEXTOR: At sufficiently small flux of depositing particles and/or sufficiently large energy of depositing particles: no enhanced re-erosion of redeposits necessary in modelling to match experimentally observed deposition? ● Modelling of impurity transport in JET inner divertor: Combined ERO/3D-GAPS modelling qualitatively reproduces impurity transport to remote area below LBSRP in dependence on strike point position Erosion at remote areas due to neutrals has to be assumed (chemical erosion and/or physical sputtering due to fast neutrals) Net erosion or net-deposition: result of balance between depositing and eroding flux Summary

39 39 ITC-22, November 2012, Toki, Japan 39 The End

40 40 ITC-22, November 2012, Toki, Japan 40 Influence of injection source on local plasma parameter M. Koltunov, M. Tokar Model of plasma disturbance for typical plasma conditions of 13 CH 4 injection experiments: Significant influence of injection at rates larger than ~4 ⋅ 10 19 /s expected. Appendix


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