1. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Influence of the Dynamic Ergodic Divertor (DED) on ELM activities and on confinement K.H. Finken 1, S. Abdullaev 1, J. Coenen 1, A. M. Jakubowski 1, R. J. E. Jaspers 2, A. Krämer-Flecken 1, M. Lehnen 1, Y. Liang 1, B. Unterberg 1, M. von Hellermann 2, Y. Xu 3, R. C. Wolf 1, U. Samm 1, O. Schmitz 1, and the TEXTOR Team 1) Institut für Plasmaphysik, Forschungszentrum Jülich, Association EURATOM/FZJ, Trilateral Euregio Cluster, D-52425 Jülich, Germany, www.fz-juelich.de 2) FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, Trilateral Euregio Cluster, PO Box 1207, 3430 BE Nieuwegein, The Netherlands, www.rijnh.nlwww.rijnh.nl 3) Laboratoire de Physique des Plasmas - Laboratorium voor Plasmafysica, Association 'Euratom- Belgian state', Ecole Royale Militaire - Koninklijke Militaire School, B-1000 Brussels, Belgium*

2. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow DED topics: Helical divertor Field line and plasma topology Impurity shielding Field line penetration Tearing modes Suppression of tearing modes

3. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Outline: Introduction to DED Effect of the perturbation field on ELMs Improved confinement by DED Summary

4. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow

5. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow m = 6, n = 2 m = 12, n = 4 m = 3, n = 1 Base modes for DED operation

6. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow H-mode characterization and ELM suppression by DED-field

7. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow 22.22.42.62.83 0 1 2 3 x 10 19 n e / m - 3 22.22.42.62.83 0 5 10 15 TEXTOR # 97315 I DED / kA 22.22.42.62.83 0 1 2 3 x 10 6 W 1.822.22.42.62.83 0 5 x 10 4 E Dia / J time / s P tot P rad Basic scenario: Ip= 240 kA/ Bt= 1.2 T-1.4 T, plasma shifted to HFS (R=1.68m / a=0.4m)

8. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Characterization of H-mode

9. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow ELM frequencies TEXTOR limiter H-mode

10. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Power threshold about twice the L-H threshold in divertor tokamaks – typical for limiter H-modes 45678910 x 10 5 0.8 1 1.2 1.4 1.6 1.8 2 P sep / W x 10 6 P L-H thresh, IAEA96 / W o no DED + with DED # 97300/1, 97312/14/15, # 98296, 98491, 99595 with ELM signature w./o. ELM signature "dithering" continued ELM - signature over 1s # 97314 # 98491 (L-H transition) Predictive RITM code calculations for 1.3 MW heating power and H/ (H+D) = 40% and TEXTOR data D. Kalupin, M. Tokar

11. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Evolution of edge pressure HFS TEXTOR # 97315 (thermal He beam*) R= 1.3 m L-H – transition H- L – transition with DED *extension of CR model by courtesy of M. Brix

12. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Substantial spin up of poloidal rotation in electron diamagnetic drift direction (indicating more negative E r ) P nbi =2.8 MW ~18 km/s ~3.6 km/s Reflectometry

13. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow ELM mitigation in 12/4 base mode ELM suppression starts at 3 kA

14. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow ELM mitigation in 12/4 base mode TEXTOR # 97315

15. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow ELM mitigation in 12/4 base mode

16. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow ELM mitigation in AC 3/1 base mode

17. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Improvement of energy confinement during H-mode modest some reduction of energy confinement with DED

18. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Confinement improvement with DED in m/n = 6/2 base mode

19. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Best conditions have been observed for strongly inward shifted plasmas low density plasmas, low collisionality Co-NBI heating I p = 310 kA; B t = 1.9 T I DED = 7.5 kA

20. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Stepwise density increase during DED-ramps

21. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Density profileDensity time trace

22. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow temperature time tracepressure time trace

23. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Related to the stepwise increase of density are characteristic heat deposition patterns Start of a new pattern is interpreted as opening of magnetic flux tubes from new island chain to wall

24. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Electric potential at divertor target probes

25. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow

26. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Poincaré plots at first and third density step Before stepAfter step 1. step 3. step

27. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Hypothesis for confinement improvement: Important are the open magnetic field lines connecting inner islands with the wall. The improved confinement may be related to potential exchange between wall and inner islands This is effective only in low collisional plasmas

28. TEC Trilateral Euregio Cluster Institut für PlasmaphysikAssoziation EURATOM-Forschungszentrum Jülich IEA Large Tokamak IA Workshop on Edge Transport in Fusion Plasmas, Krakow Summary Confinement improvements have been observed for some plasma / DED conditions. Best conditions were found for strongly heated low density plasmas shifted strongly towards the HFS (DED). Improvement has a resonance character with respect to q(a) and the DED-current. On TEXTOR, a limiter H-mode has been obtained. The ELMs were reduced at moderate ergodization levels. 12/4 and AC 3/1 base modes have been applied successfully. The energy confinement is slightly reduced by DED.