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

M Valisa – 14th IEA RFP Workshop Padova , April 26-28 2010

RFX-mod contributions to the international tokamak programme

M Valisa on behalf of the RFX team

14th IEA - RFP WorkshopConsorzio RFX, Padova April 26th - 28th 2010


RFX and the international fusion program

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


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 ProjectR Paccagnella Equilibrium, MHD and disruptions

Within the EFDA Task Forces at JET Andrea Murari: Closed Support Unit for Diagnostics


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 UnitL Novello and A Ferro Quench Protection Unit


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


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


MHD: 3D simulations of disruptions in tokamaks

R. Paccagnella, H. Strauss^ and J. Breslau* ^Courant Institute NYU*PPPL

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 theresistive wall both due to halo and eddy currents - Carry out JET simulations to compare the predictions of the modelon existing extensive data and try to refine the prediction for ITER

Poloidal Flux Ip Te

ITER case ( 15MA)


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- plasmas

Motivation: develop advanced tokamak scenarii at high and very low rotation, magnetic feedback is necessary to respond to fast MHD events like fishbones and ELMs, which may trigger RWMs and induce collapses

see P. Piovesan et al this WKSP

MPID Bp

I coils

(G)

(A)

time (s)

(G)

N

MPID Bp

#125639

- >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


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


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)


Edge physics AUG, TJII, COMPASS, HT-7

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 : Diagnostic setup

•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

combines electrostatic and magnetic pins.


Observation of field aligned filaments

Closed loop on the hodograph signature of current filaments

Current filaments flowing in the AUG Scrape Off Layer

are associated to ELM events; current is monopolar, aligned with the equilibrium B


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)


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)


RF power scan and LBO injection of Ni in JET

-6

-4

-2

0

2

4

-2 0 2 4 6 8 10

y = 2,4042 - 0,81368x R= 0,93543

-v/D

Ni (

mks

)

ICRH(MW)

H minority / H mode / low collionality/ about 12 MW NBI, 1.5MA, 3T

Average value of -v/D Ni between = 0.2 and = 0.3

Nickel

JET

The experimentally found behavior remains unexplainedas 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


Software tools to deal with W in JET

RFX ( Laura LauroTaroni) has collaborated with JET to provide models to analyse W data Superstages treatment now 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)

SXR

-500

0

500

1000

1500

2000

2500

3000

3500

4000

54.95 55 55.05 55.1 55.15 55.2 55.25 55.3 55.35 55.4 55.45

time

W/m

2

Comparision between experintal SXR emission and simulation

Transport coefficients used to Simulate the LBO experiment


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.

Example of beam depositionin an off-axis case

FAST Beam into plasma simulation

Similar studies to be donefor the ITER case in support to the ITER NNBI construction effort

(M Baruzzo and M Shneider)


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

Ongoing collaboration with MST on simulations with TRANSP ( Deyong –Anderson)

Gas Puff Imaging


MHD and Fast Ion Losses studies on ASDEX Upgrade

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.

See Gobbin et al Nucl Fus 2009 , Garcia –Munoz et al Nucl Fus 2009


Conclusion

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

Documents

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