Mitglied der Helmholtz-Gemeinschaft Reflectometry study on turbulence and ELM dynamics in limiter H–mode plasmas with and without RMP in TEXTOR. S. Soldatov 1, A. Krämer-Flecken 2, M. Yu. Kantor 2,3,4, B. Unterberg 2, G. Van Oost 1, D. Reiter 2 and TEXTOR team 1 Department of Applied Physics, Ghent University, Ghent, Belgium 2 Institut für Energieforschung - Plasmaphysik, Forschungszentrum Jülich GmbH, Association EURATOM-FZJ, Trilateral Euregio Cluster, Jülich, Germany 3 FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein, The Netherlands, 4 Ioffe Institute, RAS, Saint Petersburg , Russia

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University Contribution in physics data base on ELM control by RMPs Tuning of RMP control schemes to meet ITER requirements Correlation Reflectometry (2MHz, ms)TEXTOR features: Dynamic Ergodic Divertor => RMP m/n=3/1, 6/2, 12/4 (AC or DC) High Resolution Multi-Pass Thompson Scattering (10kHz,  r=1cm) Correlation Reflectometry (2MHz, ms) Beam Emission Spectroscopy (on Li-beam, meas.  n e, v pol ) MOTIVATION

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University Scheme of experiments Limiter H-mode w/o RMP - Plasmas parameters - Ambient turbulence (AT) and coherent modes - Rotation Limiter H-mode with RMP - Effect on the pedestal and ELMs - How influenced AT and coherent modes - Rotation Conclusions Plan

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University b c d e  bc,de =0.025 rad  cd = 0.05 rad  bd,ce =0.075 rad  be = 0.1 rad r cutoff Two O-mode heterodyne reflectometers f 0 = 26  37 GHz and 26  40 GHz n c = 0.84  1.70 and 0.84  1.98 ·10 19 m -3 Scheme of experiment  =5.75  Antennae array provides 4 probing areas and 4 distances in poloidal direction.  It is a good bases for investigation of turbulence spatial-temporal properties.  The reliability of velocity measurements increases.

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University K.H. Finken et al., Nucl. Fus. 47 (2007), 522. B. Unterberg et al., 34th EPS Conference on Plasma Phys. 2007, P Limiter H-mode scenario in TEXTOR

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University Limiter H-mode scenario with NBI co injection Reduced Bt ( ≤1.9T ), plasma limited by inner wall power threshold MW at 1.3T Confinement improvement <40% High frequency ELMs ( Hz) B. Unterberg, 16 th European Fusion Physics Workshop, Cork, Ireland, 1-3 December 2009 K.H. Finken et al., Nucl. Fus. 47 (2007), 522. B. Unterberg et al., 34th EPS Conference on Plasma Phys. 2007, P Ip=235 kA, B t =1.3 T, R=1.72 m, a=0.44 m (q a =3.7), P tot =1.6 MW (NBI co-current)

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University Plasma profiles dynamics (High Resolution Multi-Pass TS). Pedestal mostly manifests itself in density. NeNeNeNe TeTeTeTe pepepepe Between ELMs DDDD Reflectometer covers 0.8<  < y TEXTOR # , t= 2.5 s

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University Turbulence spectrum trough L-H transition.  c =41.5 cm  c =40 cm  c =39 cm  c =37.8 cm Ohmic H NBI co Quasi coherent mode at f~13kHz is observed after L-H transition Quasi coherent mode at f~13kHz is observed after L-H transition. No mode in L-mode phase. H L Radial scan of ~ 4 cm N23

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University QC modes of 48,110 kHz and 13kHz are located inside  c=41.5 cm. Poloidal m numbers from CR data are estimated (assuming RBR): 13kHz m~5, 48kHz m~19, 110kHz m~43 Two last agree with peripheral HF coherent mode on C-Mod in EDA [Hubbard PoP2001] m~19 m~43 m~5 Spectrum overview vs radius ( in Between ELMs ). Modes amplitude m~5

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University Turbulence rotation. L and H mode. NBI1 imparts the co-current toroidal momentum that results in the   directed in IDD direction (helicity Bt↑↓Ip ). NBI1 imparts the co-current toroidal momentum that results in the   directed in IDD direction (helicity Bt↑↓Ip ) E+5 Rotation shear  s = dv/dr ~12.0 E+5 s -1 at  =42 cm 2.5  5 E+5 Turb. decorrelation rate  dc = 2.5  5 E+5 s -1 at  =42 cm. The rotation shear limiter  s >  dc

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University Ambient turbulence in H-mode

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University The turbulence spectrum modulated in accordance with ELM events. Spectrum broadens during the ELM crash and shrinks in between ones. Integral level varies by several times. Refl. spectrum evolution on ELM time scale

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University Silent Stage  increases Recovery period contains Silent Stage when  n/n drops below Ohmic level and  increases indicating pedestal formation.  ↑  c  const  ↑,  c  const => => => => => => => => n e decreases at  >  c. Turbulence level increase before ELM (like for ELMs type I)  cc Detailed analysis of turbulence level  80<f<500kHz. Ln factor accounted very accurate owing to HRTS data

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University

H-mode + RMP

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University Pedestal degrades with RMP amplitude ELM =360 Hz Reduction of D  ELM burst B. Unterberg et al., PSI Conference 2008 B. Unterberg, 16 th European Fusion Physics Workshop, Cork, Ireland, 1-3 December 2009 Effect from RMP application DED coils layout with RMP amplitude: pedestal degrades ELM ampl. decreases ELM increases The features are the same as observed on diverter machines (JET, DIIID)

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University QC modes both at 13 and 48 and 110 kHz die away when RMP amplitude increases. The turbulence spectral integral increases with I DED by ~2 times within 1<I DED <3.75 kA. Spectral characteristics (r=37cm, r/a=0.83) “13 kHz”

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University MC see broader peak 10<f<17 kHz than Reflectometer. There were not found a direct correlation between MC and Reflectometer data. The explanation – ”multiple variable mix” of several modes like EHO observed in DIIID. [K.Burrell et al, PoP2001] N8

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University T ELM DD MC Magnetic fluctuations were studied on the post cursor subject in # In the view of not regular response in MC statistical analysis was implemented within 1.8 ~400 ELM crashes. ~2ms Two clear peaks: Pre cursor (~-150us) and Post cursor (~1300 us) is more localized (FWHM Pre =150us) means more regular Precursor is more localized (FWHM Pre =150us) means more regular compare with Postcursor but less representative (N/Ntot~27%) Post cursor is distributed broader: FWHM Post =500us, and more representative: N/Ntot~40% Most likely that the rest of magnetic bursts (~40%) are not related with the ELMs. Most likely that the rest of magnetic bursts (~40%) are not related with the ELMs. Deep within 0 nearly no magnetic fluctuations in the beginning of recovery stage Deep within 0 nearly no magnetic fluctuations in the beginning of recovery stage ~2ms Analysis of 13kHz mode in magnetic fluctuations. Data for 2 poloidal probes 0 o and 75 o agrees well.  t [s]

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University Turbulence rotation. RMP influence. RMP reduces the rotation shear at periphery of H-mode plasmas. It agrees with pressure profile deterioration observed with TS

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University Conclusions Limiter H-mode in TEXTOR is characterized by the following: 1) 13 kHz mode (5<m<6) is found both in Correlation Reflectometer (CR) and MC data manifests the properties of precursor mode (like for type III ELMs). It is located several cm inside the separatrix very close to pedestal region. It disappears gradually with pedestal degradation. No correlation found between CR and MC data (”multiple variable mix” ?). Similar to EHO mode studied at DIIID. 2) QC oscillation with m~19 and 43 were identified also inside separatrix. Their frequency and radial location agree with QC mode observed at C-Mod. 2) The significant shear of plasma perpendicular rotation is found around the pedestal. Silent Stage 3) Turbulence level at pedestal evolves by several times according to ELM activity. Inside the recovery period the Silent Stage was found which is characterized by extremely low turbulence level and grow of probing wave phase. 4) In most cases turbulence level increases before ELM crash as usually observed for type I ELMs. In H-mode plasmas the turbulence rotation exhibits strong shear near pedestal region which exceeds the decorrelation time of AT. RMP application decreases the rotation shear in H-mode plasmas and pedestal quality. RMP leads to increase of the turbulence level in the mean and all coherent modes die away.

IRW9 Lisbon 4-7 July 2009 S. Soldatov Ghent University “13 kHz” QC mode degrades with RMP amplitude. DED 2.5kA Frequency [kHz] Turbulence spectrum. Response on RMP.  c [cm] DED 1kA DaDa # #107318