RFX-mod contributions to the international tokamak programme M Valisa on behalf of the RFX team

1. RFX-mod contributions to the international tokamak programme M Valisa on behalf of the RFX team 14th IEA - RFP Workshop Consorzio RFX, Padova April 26th - 28th 2010

2. RFX contribution to the international fusion program is substantial RFX mode program is well integrated in the European (Euratom-EFDA) and international (IEA) programs There are several topics of common interest between RFP TOK and stellarator, regarding both physics and technology Recognized the importance of sharing knowledge and expertise (crossfertilization) RFX-grown young researchers are disseminated in other labs RFX and the international fusion program

3. Significant Institutional contribution RFX resources for leadership of European structures F Gnesotto : Leader of the EFDA STAC P Martin : leader of Equilibrium and Stability EFDA Topical group Within the EFDA Task Force Integrated Tokamak Modelling G. Manduchi : ISIP Infrastructure and Sofware Integration Project R Paccagnella Equilibrium, MHD and disruptions Within the EFDA Task Forces at JET Andrea Murari: Closed Support Unit for Diagnostics

4. RFX and the “Broader Approach” An agreement between EU and Japan articulated in three projects - IFMIF/EVEDA For R& D on materials - IFERC ( a common reseach center) - A Satellite device: JT-60SA E Gaio TCG member T Bolzonella . Physics Integration Unit L Novello and A Ferro Quench Protection Unit

5. Main collaboration themes • RFX gives contributions to the Tokamak Fusion Program • in several fields where a common interest exists • MHD studies and control • Transport : Edge transport • Impurity tranport, • Fast particles • Beam into plasma

6. MHD . RWM studies for JT-60SA RWM control experiments on RFX-mod in support to JT60-SA design RFX, Full coils coverage can be downgraded via software to emulate the discrete coil distribution in JT-60SA JT-60SA PRELIMINARY RESULTS ( see Bolzonella,Baruzzo, Takechi -This wks) - RWM’s do not deform, to some extent, under “reduced” control - Generated sidebands must be carefully treated for the potential RFA effects on marginally unstable modes

7. MHD: 3D simulations of disruptions in tokamaks ^Courant Institute NYU *PPPL R. Paccagnella, H. Strauss^ and J. Breslau* Disruptions produced by VDEs and internal kink instability analyzed by 3D MHD + structures codes - Produce non-axisymmetric forces with JET - Projections have been made for ITER - In the model forces are generated by jumps of the magnetic field across the resistive wall both due to halo and eddy currents - Carry out JET simulations to compare the predictions of the model on existing extensive data and try to refine the prediction for ITER ITER case ( 15MA) Poloidal Flux Ip Te

8. #125639 bN MPID Bp (G) MPID Bp (G) I coils (A) time (s) MHD: Improve the dynamic response of feedback in DIII-D • AC compensation: for fast feedback of • - current-driven RWMs in Ohmic plasmas • - fishbone-driven RWMs in high-b plasmas • Motivation: develop advanced tokamak scenarii at high b and very low rotation, magnetic feedback is necessary to respond to fast MHD events like fishbones and ELMs, which may trigger RWMs and induce b collapses • - >AC compensation reduces the I coil currents • -> DC compensation may produce errors (over or out-of-phase compensation) that at high beta may me amplified. This experience suggeted expts to be run on RFX see P. Piovesan et al this WKSP

9. Provided and benchmarked a code for NTM radial localization (coherence between fast coils, and ECE . Yields constraints on the q profile. (M Baruzzo) A systematic discrepancy against another mode localization code led to reveal a systematic 3% error in the evaluation of JET total magnetic field. Analyzed confinement vs mode onset as a function of mode’s position: the larger the mode radius the higher the drop in H98 Investigated the double nature of tearing and kink modes. MHD studies on JET

10. Edge physics AUG, TJII, COMPASS, HT-7 Edge turbulent structures ( blobs) are a common feature across the many magnetic configurations ( and also astrophysical plasmas) Their nature is intermittent and filamentary ( Spolaore et al PRL 2009 165001, Martines et al PPCF 2009 124053) Their origin is interchange like or also drift wave-like ( Vianello et al Nucl. Fusion Letter 2010 042002)

11. Characterization of current filaments in ASDEX Upgrade-in collaboration with IPP Garching, RISO national laboratory, University of Innsbruck physics of ELMs, triggered vs. natural. properties of turbulence of L-mode and inter-ELM regimes L- H transition physics momentum transport and Maxwell stress measurement have been performed in the ELM/ inter-ELM phase: bursty-like behavior during ELM phases. Current density and vorticity of turbulent structures in the stellarator TJ-II and the tokamak COMPASS-D in different regimes ( beta, collisionality etc) in collaboration with CIEMAT-Madrid and IPP-Prague Collaboration with HT-7 on edge data analysis just started Edge physics AUG, TJII, COMPASS, HT-7

12. EDGE Physics : Diagnostic setup • combines electrostatic and magnetic pins. • Probe developed to measure electromagnetic fluctuations in the SOL plasma. • Information on radial and poloidal electric field, Density (from ion saturation current) and temperature from sweeping probe • Information on the fluctuation of the three components of the magnetic field Collaboration between: CONSORZIO RFX-Italy,Association EURATOM/ÖAW-Austria, IPP-Garching, RISØ Laboratory-Denmark

13. Observation of field aligned filaments Current filaments flowing in the AUG Scrape Off Layer are associated to ELM events; current is monopolar, aligned with the equilibrium B Closed loop on the hodograph signature of current filaments

14. 4.6 Edge Physics : Gas Puff Imaging on C-mod • correlation of edge turbulence with collisionality and pressure profile, via the analysis of a Gas Puff Imaging diagnostic similarly to what it has been done on RFX-mod. • General statistical properties of turbulence worked out by comparing C-mod and RFX-mod data. • Found a link between the packing factor fp ( the fraction of edge plasma occupied by coherent structures) and the collisionality • There is a similarity between edge turbulence and edge profiles in RFX-mod and C- mod ( M Agostini ,P Scarin)

15. Impurity density control: JET Major issue for reactors ( energy dissipation/ impact on fusion reactivity) Central electron heating is a good candidate for a feedback system against impurity peaking in Tokamaks, Stellarators ( perhaps RFP’s too? ) Carried out expts in JET with ICRH power scan to quantify/qualify the effect on metals such as Ni and Mo injected via Laser Blow Off Simulations carried out with the gyrokinetic code GS2 (then also used for Turbulence studies on RFX)

16. RF power scan and LBO injection of Ni in JET H minority / H mode / low collionality/ about 12 MW NBI, 1.5MA, 3T Average value of -v/D Ni between r = 0.2 and r = 0.3 JET Nickel The experimentally found behavior remains unexplained as turbulent models (GS2) would predict always inward pinch. ME Puiatti et al Phys Plasmas 2006 Carraro Et al EPS Conf 2008 , Valisa et al EPS Conf 2009

17. Software tools to deal with W in JET RFX ( Laura LauroTaroni) has collaborated with JET to provide models to analyse W data Superstages treatmentnow available , capable to compute the transport of W and to compute the related SXR emissiviy, the most useful experimental datum to compare Experiment and models 68373 3.2T/2.3MA 4.5 MW ICRH, 8.9MW NBI, 0.5 MW LHCD D (m2/s) V (m/s) Comparision between experintal SXR emission and simulation Transport coefficients used to Simulate the LBO experiment

18. FAST Beam into plasma simulation • Code CRONOS: Work has started also (CEA), in collaboration with CEA CADARACHE and ENEA Frascati, • Study the fast particle distribution generated by the NBI and provide suitable specifications for the beam injector . To be coupled to simulations of ICRH heating. Similar studies to be done for the ITER case in support to the ITER NNBI construction effort Example of beam deposition in an off-axis case (M Baruzzo and M Shneider)

19. FAST Beam into plasma simulation Beam into plasma issues useful also for RFX Where 1.5 MW TPE RX beam is going to be installed in collaboration with AIST Tsukuba Gas Puff Imaging Ongoing collaboration with MST on simulations with TRANSP ( Deyong –Anderson)

20. FIL caused by NTMs and TAEs and Sierpes Channelling of fast-ions in the particle phase space may have severe consequences on structures . NTM inducers FIL losses explained as a result of the drift islands formed by the fast-ions in particle phase space. Overlapping of these drift islands leads to enhanced losses Loss of ICRH fast-ions explained by a wave–particle resonant interaction through the wave and fast-ion orbital frequencies. New core-localized MHD fluctuation in AUG, the Sierpes mode : a non-pure Alfvenic fluctuation which appears in the acoustic branch, TAEs and Sierpes spatial overlapping enhances TAE induced fast-ion transport. MHD and Fast Ion Losses studies on ASDEX Upgrade See Gobbin et al Nucl Fus 2009 , Garcia –Munoz et al Nucl Fus 2009

21. A significant contribution to the tokamak programme in fields of common interest is providing Useful links New ideas and tools Thoughtful redirection of RFX scientific programme Diffusion of the interest for the RFP programmes Conclusion