Burning Plasma Simulations: Edge Issues

1. D. P. Coster Max Planck Institute for Plasma Physics,EURATOM Association, Garching, Germany Burning Plasma Simulations: Edge Issues Burning Plasma Simulations: Edge Issues [Coster]

2. Burning Plasma Simulations: Edge Issues [Coster] Outline • Why are edge issues important for burning plasma simulations? • All the external sources pass through the edge • The non-neutron waste products are all removed via the edge • Much of the performance of the core is determined by the edge • The edge provides constraints on the core

3. Burning Plasma Simulations: Edge Issues [Coster] Outline • Why are edge issues important for burning plasma simulations? • All the external sources pass through the edge • Particle • Gas puff • Pellets • NBI • Energy • NBI • RF • The non-neutron waste products are all removed via the edge • Much of the performance of the core is determined by the edge • The edge provides constraints on the core

4. Burning Plasma Simulations: Edge Issues [Coster] Outline • Why are edge issues important for burning plasma simulations? • All the external sources pass through the edge • The non-neutron waste products are all removed via the edge • Particles • D, T • He • Energy • Much of the performance of the core is determined by the edge • The edge provides constraints on the core

5. Burning Plasma Simulations: Edge Issues [Coster] Outline • Why are edge issues important for burning plasma simulations? • All the external sources pass through the edge • The non-neutron waste products are all removed via the edge • Much of the performance of the core is determined by the edge • H-mode barrier • He concentration • Impurities • The edge provides constraints on the core

6. Burning Plasma Simulations: Edge Issues [Coster] Outline • Why are edge issues important for burning plasma simulations? • All the external sources pass through the edge • The non-neutron waste products are all removed via the edge • Much of the performance of the core is determined by the edge • The edge provides constraints on the core • Minimum separatrix density • ELMs • Particle throughput

7. Burning Plasma Simulations: Edge Issues [Coster] What tools are currently available? • Mainly a European perspective • Edge transport codes • Global (in the sense of whole domain, consistent) • SOLPS (B2-Eirene) • EDGE2D-NIMBUS • Fluid plasma (2d) • Kinetic neutral (2d or 3d) • Multiple species • Local (limited domain, against a fixed background) • ERO • Kinetic trace impurities • 2d/3d • ASCOT • Fast ions or electrons • PIC codes

8. Burning Plasma Simulations: Edge Issues [Coster] “Global” codes, I • Fluid plasma (2d) • kinetic plasma effects not properly treated • Flux limiters • Should we investigate fluid/kinetic hybrids? • 2d • Ignore 3D effects • Localised recycling, sources etc. • Multiple species • Mixed material issues (later) Th. Pütterich

9. Burning Plasma Simulations: Edge Issues [Coster] “Global” codes, II • Fluid plasma (2d), cont • Solution domain somewhat limited • Doesn’t extend all the way to the vacuum vessel • What are the appropriate boundary conditions there? • Implications for • heat/particle loads in main vessel • Sources of impurities

10. Burning Plasma Simulations: Edge Issues [Coster] “Global” codes, III • Kinetic neutral (2d or 3d) • Kinetic: coupling to a Monte-Carlo code • More accurate, slower • Monte-Carlo Noise • (Fluid: usually not full Navier-Stokes • Not as accurate • Own temperature?) • Still discussion of role of physics • He elastic collisions • Hydrocarbon break up chains • Vibrational excitations • Often details of bypasses, wall out-gassing neglected • Neutral-neutral collisions and optically thick regions

11. Burning Plasma Simulations: Edge Issues [Coster] Some issues, I • Impurities • Intrinsically produced • Somewhat simplified erosion/deposition models • Plasma solution domain usually doesn’t extend to vacuum vessel • Problem with main chamber sources • PSI models usually too simple • Usually not affected by the plasma in the simulations • Heating • Out-gassing/absorption • Isotope exchange • ELM target cooling with Ar at inner target • Hydrocarbon chemistry including T co-deposition • How can we improve them? Th. Pütterich

12. Burning Plasma Simulations: Edge Issues [Coster] separatrix 80 mm CH4 CH2 CH CH4 0 80 mm 0 CH+ C C+ Some issues, I: solution path A. Kirschner • Effects can be studies using local codes • ERO • Local erosion / deposition analysis • Detailed model for processes • Including CxDy • If effects are important need to, either • Couple to global code • Incorporate physics in global code

13. Burning Plasma Simulations: Edge Issues [Coster] Some issues, II Chankin, “SOLPS modelling of ASDEX-U H-mode Plasma”, Edge Physics Forum, Jan 2005 • Effects of fast particles(?) • Differences in energy seen by Langmuir probes and Thermography? • Look at with kinetic codes • ASCOT • Monte-Carlo treatment of fast ions or fast electrons • PIC • Problem with time-space scales (particularly if more than one space dimension) • Need to have recycling physics Unpuffed, H-mode, AUG

14. Burning Plasma Simulations: Edge Issues [Coster] Some issues, III • Transport coefficients are inputs to the global (and local) codes • Need 1st principles treatment of radial transport • 3 options • Parametrize radial and poloidal dependence of transport coefficients • Non-diffusive nature (+ pinches) • Couple transport and turbulence codes • Move all the physics currently in the transport codes into the turbulence codes Nishimura (while a PostDoc at IPP)

15. Burning Plasma Simulations: Edge Issues [Coster] DivIIb/18737 500000 EXP DivIIb/18737 B2 no drifts DivIIb/18737 B2 with drifts 30 400000 EXP 6e+19 B2 no drifts EXP 25 B2 with drifts B2 no drifts 300000 5e+19 B2 with drifts 20 power flux density (W/m^2) 4e+19 200000 15 Te (eV) 3e+19 electron density (m^-3) 100000 10 2e+19 0 5 -0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 1e+19 s-s_sep_outer_target (m) 0 -0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 0 -0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 s-s_sep_outer_target (m) s-s_sep_outer_target (m) Some issues, IV • Drifts • Still not complete agreement on the equations to be implemented • Not nearly as robust as the non-drift versions • Often have additional time-step limitations • Sometimes have problems with extending to far into the core • Sometimes have problems with reduces solution domain in terms of plasma parameters • Need to develop a technique for moving from drift treatment (2d) to a neoclassical (1d radial) treatment

16. Burning Plasma Simulations: Edge Issues [Coster] Integration • Edge with core • Edge with PFC

17. Burning Plasma Simulations: Edge Issues [Coster] Integration Fichtmueller et al, EPTSW • Edge with core • Couple core and edge • COCONUT • JETTO-SANCO-EDGE2D-NIMBUS • Add core physics to edge codes • SOLPS efforts are a start • Edge with PFC Buerbaumer, Bonnin

18. -2 -1 -1 -1 Burning Plasma Simulations: Edge Issues [Coster] neutral energy spectra (m s sr eV ) 13 10 ITER AUG 12 10 11 10 10 10 1 10 100 1000 energy (eV) Integration, II 2 • Edge with core • Source from ASTRA • Use B2.5-I to fit to exp. (Y.P. Chen) • Can then use to examine W erosion (Kukushkin) • Used as a starting point for ELM simulations • Or for disruptions (Konz) • Edge with PFC 1 4 3

19. Burning Plasma Simulations: Edge Issues [Coster] Integration • Edge with core • Edge with PFC • Couple edge codes • “global”and “local” • Add physics from “local” codes to “global” codes

20. Burning Plasma Simulations: Edge Issues [Coster] Plate surface temperature for different plate thicknesses 2000 0.00 0.01 1800 0.02 1600 0.03 0.04 1400 0.05 0.10 1200 0.15 0.20 1000 0.30 800 0.40 Outer target plate surface temperature (K) 0.50 600 400 200 0 0.1 0.2 0.3 0.4 s-s_sep outer target (m) New developments • Working towards more integrated models • Integrating plasma and plate • SOLPS5-B2 • Fluid neutrals • Thermal model for the plate  • Latest Roth chemical sputtering formula • Working towards modelling mixed materials

21. Burning Plasma Simulations: Edge Issues [Coster] Plate Time Factor = X 1000 10000 dep PTF=1e3 MM=on dep PTF=1e3 MM=off 9000 ero PTF=1e3 MM=on ero PTF=1e3 MM=off 8000 7000 6000 5000 erosion or deposition @ 112 (mono-layers) 4000 3000 2000 1000 0 0 100 200 300 400 500 600 700 800 900 1000 time New developments } • Add accounting of erosion and deposition (B2 side only so far) • Added a simple mixed materials model Without re-erosion of deposited material With re-erosion of deposited material } D+C+He, SOLPS-B2, AUG

22. Burning Plasma Simulations: Edge Issues [Coster] mixed_materials ntim=50000 dtim=1e-4 PTF=1e4 100000 net_monolayer_deposition_C net_monolayer_erosion_C 10000 net_monolayer_deposition_Be net_monolayer_erosion_Be 1000 100 10 monolayers@112 1 0.1 0.01 0.001 0 10000 20000 30000 40000 50000 seconds New developments • Add accounting of erosion and deposition (B2 side only so far) • Added a simple mixed materials model • Can now treat Be main chamber wall and C divertor plates • New time-scales! D+C+He+Be, SOLPS-B2, AUG

23. Burning Plasma Simulations: Edge Issues [Coster] Summary • Need to think about the edge for Burning Plasma Simulations • Progress is being made • But we still have a way to go! • Challenges • The same as more many other areas • Time-scales • Space-scales • Dimensionality