1. Dominik Schega (1), S.S.Abdullaev (1), M.Clever (1), K.H.Finken (1), M.Jakubowski (2), Y.Kikuchi (3), M.Lehnen (1), O.Schmitz (1), G.Sewell (4), H.Stoschus (1), R.Wolf (2), B.Unterberg (1) Comparison of experimentally observed footprint structures with modeling Mitglied der Helmholtz-Gemeinschaft (1)Institut für Energieforschung - Plasmaphysik - FZ-Jülich GmbH Assoziation EURATOM - Forschungszentrum Jülich, Trilateral Euregio Cluster (2)Max Planck Institut für Plasmaphysik (3)Department of Electrical Engineering and Computer Sciences, Graduate School of Engineering, University of Hyogo (4)Mathematics Dept University of Texas El Paso Institut für Energieforschung - Plasmaphysik Assoziation EURATOM – FZJ GRK1203 Conference – Bad Breisig – 27-28.10.2008 Trilateral Euregio Cluster

2. 10. Juni 2016 Slide 2/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Footprints origin

3. 10. Juni 2016 Slide 3/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Outline 1.Motivation for finding MHD effects which explain experimental data 2.Magnetic field structure in vacuum approach 3.Screening currents as MHD effects in plasma 4.Magnetic field structure in MHD approach 5.Detailed comparison of the measured edge structures to modeling 6.Conclusions

4. 10. Juni 2016 Slide 4/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Motivation – shot #106103 Magnetic field measurement Target structure DED current [kA] density Mirnov coils 6/2 DED base mode

5. 10. Juni 2016 Slide 5/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Motivation – shot #106103 COINCIDENT I d =1050 [A] Magnetic field measurement Target structure DED current [kA] density 6/2 DED base mode

6. 10. Juni 2016 Slide 6/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Motivation – shot #106103 COINCIDENCES I d =1050 [A] I d =3250 [A] Magnetic field measurement Target structure DED current [kA] density 6/2 DED base mode

7. 10. Juni 2016 Slide 7/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Vacuum DED field structures I d =1050 [A]

8. 10. Juni 2016 Slide 8/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Vacuum DED field structures I d =3250 [A]

9. 10. Juni 2016 Slide 9/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Linearized 5-field two-fluid drift-MHD model  Model base on a perturbation method, description of equilibrium is necessary  All modelled quantities are computed along the magnetic field lines due to magnetic confinement – a field aligned coordinate system is necessary. That is important for the DED error field spectrum as well.  The perturbed quentities are being Fourier decpomposed – single mode analysis Neglected:  Shafranov shift  all nonlinear terms  poloidal coupling of Fourier modes 5 fields:  Density  Vorticity  Ion velocity  Magnetic vector potential  Electron temperature

10. 10. Juni 2016 Slide 10/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Resonant surface Analogus to Lissajous curves  x =2  x =2.01  x =2.123  y =1

11. 10. Juni 2016 Slide 11/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Diamagnetic effect The diamagnetic effect appears in the plasma due to the pressure gradient density temperature r Net current More particles Less particles Higher velocities Lower velocities

12. 10. Juni 2016 Slide 12/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Electron diamagnetic drift effect The diamagnetic drift effect result in plasma as drift waves r R

13. 10. Juni 2016 Slide 13/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Electron diamagnetic drift effect The diamagnetic drift effect result in plasma as drift waves Measured frequencies match approximately with the estimated from density and temperature measurements Magnetic field measurement r R

14. 10. Juni 2016 Slide 14/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Screening effect m34567 r res 0,610,720,800,880,95 mm 1,03 0,47 mm 000058° Only edge currents can change the edge structures

15. 10. Juni 2016 Slide 15/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Screened field structures I d =1050 [A] Vacuum 7/2 13/4 5/2 7/2 13/4 5/2 m/n

16. 10. Juni 2016 Slide 16/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Screened field structures I d =3250 [A] Vacuum 7/2 5/2 m/n

17. 10. Juni 2016 Slide 17/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Boomerang structures of the magnetic field sugest a screened » vacuum field transition?

18. 10. Juni 2016 Slide 18/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Boomerang structures of the magnetic field In order to conclude more deeper analysis is necessary. 6/2 trace? 7/2 trace 13/4 trace

19. 10. Juni 2016 Slide 19/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ Conclusions  We do not know what really happened with the MHD activity which frequency has vanished.  So far it is not clear if the linearized 5-field model is the tool to explain the changes in the magnetic field edge structures.  It seems there are similarities to both approaches. For lower error fields the structures seem to look like in the screening case. For the higher error fields the structures seem to look like in the vacuum case.  Deeper analysis are ongoing...

20. 10. Juni 2016 Slide 20/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ

21. 10. Juni 2016 Slide 21/18 Institut für Energieforschung – Plasmaphysik Assoziation EURATOM – FZJ HH