1 / 24

Application of a multiscale transport model for magnetized plasmas in cylindrical configuration

Application of a multiscale transport model for magnetized plasmas in cylindrical configuration. Workshop on Plasma Material Interaction Facilities. | Christian Salmagne 1 , Detlev Reiter 1 , Martine Baelmans 2 , Wouter Dekeyser 2.

Download Presentation

Application of a multiscale transport model for magnetized plasmas in cylindrical configuration

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Application of a multiscale transport model for magnetized plasmas in cylindrical configuration Workshop on Plasma Material Interaction Facilities | Christian Salmagne1, Detlev Reiter1, Martine Baelmans2, Wouter Dekeyser2 1 Institute of Energy and Climate Research - Plasma Physics, Forschungszentrum Jülich GmbH 2 Dep. of Mechanical Engineering, K.U.Leuven, Celestijnenlaan 300 A, 3001 Heverlee, Belgium

  2. Outline 0. Motivation • Using the ITER divertor code B2-EIRENE for PSI-2 • Simulation of PSI-2 • Extension of the numerical model • Summary & Outlook

  3. 0. Motivation • Linear plasma device PSI-2 has been transferred from Berlin to FZJ last year. • The modeling activities carried out in Berlin are not usable anymore and are rebuild in Jülich, using the ITER divertor code B2-EIRENE. • Modeling of PSI-2 creates the possibility of an additional analysis of a plasma that resembles the edge plasma of a Tokamak in important points. • That gives the opportunity to verify and improve the Code with another type of experiment.

  4. Using the ITER divertor code B2-EIRENE for PSI-2 • PSI-2 Jülich • Using the B2-EIRENE code for a linear device • Governing equations • Boundary conditions, grid and used parameters

  5. PSI-2 Jülich • Six coils create a magnetic field B < 0.1 T. • Plasma column of approx. 2.5 m length and 5 cm radius • Densities and temperatures: 1017 m-3 < n < 1020 m-3, Te < 30 eV • MFP of electrons indicate that fluid approximation is likely to be valid

  6. Use of B2-EIRENE code for a linear device Direct use of B2-EIRENE (SOLPS) for PSI-2 is possible, but the coordinates have to be adapted polar (toroidal) coordinates are neglected (symmetry is assumed) Plasma source Midplane topol. equiv. Aspect ratio: a/R=∞ Target Target Tokamak MAST PSI-2

  7. Boundary conditions, grid and used parameters • First aim: Reproduction of radial profiles using all existing information about the simulation from Berlin [1] • Boundary conditions: • Walls perpendicular to the field lines: Sheath conditions • Axis of the cylinder: vanishing gradients in Te,TI and n • „Vacuum-boundary“ and anode: 1cm decay length in Te,TI and n • Parameters: • Pumping rate: 3500l/s • Neutral influx(D2): 6.32 x 1019 s-1 • Anomalous diffusion: Din = 3.0m2/s; Dout = 0.2 m2/s • Perpendicular heat conduction: κe,in= 5.0 m2/s; κe,out= 11.0 m2/s • Source next to anode at given temperature(Te = 15 eV; TI = 5 eV) • [1] Kastelewicz, H., & Fussmann, G. (2004). Contributions to Plasma Physics, 44(4), 352-360

  8. Simulation of PSI-2 • Summary of existing results: • [1] Kastelewicz, H., & Fussmann, G. (2004). Contributions to Plasma Physics, 44(4), 352-360 • [2] Vervecken, L. (2010). Extended Plasma Modeling for the PSI-2 Device. Master thesis. KU Leuven • Reproduction of existing numerical and experimental results • Dependency on kinetic flux limiter

  9. Summary of existing results • Modeling activities in Berlin with former B2-EIRENE Version SOLPS4.0, 1995, Summary can be found in [1] • In [2] the model was rebuild, old results could already be partially reproduced. • Figures: Radial profiles at two different positions, Coefficients for anomalous transport adapted to fit experiment [1]

  10. Reproducing existing results • First results did not match old results • „flux limiter“ was introduced into B2 to compensate kinetic effects • Parallel heat conductivity is limited to: with parameter FLIM • Different values of FLIM found in old input • It is not possible to reconstruct, which value was used in [1] FLIM = 0,8

  11. Dependency on kinetic flux limiter • Dependency on the flux limiter indicates the importance of kinetic effects • Additional free parameter influencing the parallel transport • Experimental values at at least two axial positions needed • Values for the flux limiter can be obtained using the comparison with experimental data or a complete kinetic model of PSI-2

  12. Extension of the numerical model • Extension of the neutral particle model using a collisional radiative model an metastable states • Incorporation of parallel electric currents

  13. Extension of the neutral model Refinement • Model [1]: neutral model as used in [1] • Model I: Collisional radiative model for H2+ and H2 • Model II: Vibrationally excited states treated as metastable • Particle and heat fluxes on the neutralizer plate strongly depend on the used model • Plasma density and temperature also change strongly

  14. Extension of the neutral Model: Recombination • Reaction rates show that H2+-MAR is the most important recombination channel • Most recombination takes place at neutralizer and cathode • 3 body recombination and radiative recombination are unimportant in the model

  15. Model [1] Extension of the neutral Model: MAR • H2+-MAR rates also depend on the used model • With Model I rates are overestimated in the target chamber and underestimated at the anode • Vibrationally excited states have to be modeled as metastable Ratio Model I / Model II Model I Model II

  16. Incorporation of parallel electric currents • The plasma potential is not calculated and the potential drop is only important for the heat flux, and thus for the boundary condition for the electron energy. • For equal electron and ion temperatures it can be approximated as: • Since the variation with the temperatures is small, the potential drop is provided as a constant input parameter

  17. Incorporation of parallel electric currents • In “extended B2” [3] currents are incorporated. Then, the potential drop depends on the current and changes to: • That also changes the electron energy flux • In this version the possibility to set the wall potential for each wall differently exists. • That makes it possible to bias the neutralizer wall [3] Baelmans, M. (1993). Code Improvements and Applications of a two-dimensional Edge Plasma Model for toroidal Fusion Devices. Katholieke Universiteit Leuven.

  18. Incorporation of parallel electric currents:Code verification • Normalized current density: • Normalized heat flux density: • Heat flux and electric current behave exactly asexpected when the potential is changed

  19. Incorporation of parallel electric currents • When no potential is applied, the direction of the current is depending on the radial position • The direction of the electric currents can be influenced by changing the potential at the neutralizer plate • Direct influence of strong current densities on the electron temperature can be seen

  20. Incorporation of parallel electric currents • Ion temperature and plasma density do not change significantly • Electric current on the neutralizer plate changes and reaches a saturation for negative potentials of the neutralizer • Heat flux on the wall also changes and has a minimum near the floating potential • Minimal heat flux stilllarger than in case of disabled currents • Heatflux not minimal, if total current vanishes

  21. Summary & Outlook • Summary • Numerical model was rebuild and old numerical and experimental results were reproduced using the ITER divertor code B2-EIRENE. • A dependency on the kinetic flux limiter was found. • The neutral particle model was improved and it was shown that the correct treatment of the vibrationally excited states is crucial in the model. • B2-EIRENE can account for parallel electric currents in a linear machine • Outlook: • Classical drifts and diamagnetic currents will be introduced. • Experimental data is needed to compare target biasing effects and to cope with the dependency on the kinetic flux limiter. • Neutral particle simulation can be further extended. The model of the reactions at the walls has to be checked. • Impurities will be introduced.

  22. Thank you for your attention!

  23. Governing equations • Continuity equation: • Parallel momentum equation: • Radial momentum equation:

  24. Governing equations • Electron and ion energy equations:

More Related