1 / 26

Contribution in physics data base on ELM control by RMPs

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

farhani
Download Presentation

Contribution in physics data base on ELM control by RMPs

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Reflectometry study on turbulence and ELM dynamics in limiter H–mode plasmas with and without RMP in TEXTOR. S. Soldatov1, A. Krämer-Flecken2, M. Yu. Kantor2,3,4, B. Unterberg2, G. Van Oost1, D. Reiter2 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, 52425 Jülich, Germany 3 FOM-Institute for Plasma Physics Rijnhuizen, Association EURATOM-FOM, Trilateral Euregio Cluster, Nieuwegein, The Netherlands, www.rijnhuizen.nl 4 Ioffe Institute, RAS, Saint Petersburg 194021, Russia

  2. MOTIVATION • Contribution in physics data base on ELM control by RMPs • Tuning of RMP control schemes to meet ITER requirements • 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, 0.8<r/a<0.95, TFreqStep>50ms)Beam Emission Spectroscopy (on Li-beam, meas. ne, vpol)

  3. Plan • 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

  4. Scheme of experiment Two O-mode heterodyne reflectometers f0= 2637 GHz and 2640 GHz nc= 0.841.70 and 0.841.98 ·1019m-3 rcutoff =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. bc,de=0.025 rad cd= 0.05 rad bd,ce=0.075 rad be= 0.1 rad b c d e

  5. Limiter H-mode scenario in TEXTOR • K.H. Finken et al., Nucl. Fus. 47 (2007), 522. • B. Unterberg et al., 34th EPS Conference on Plasma Phys. 2007, P-2.053

  6. Limiter H-mode scenario with NBI co injection BT = 1.3 T, qa = 3.7, R = 1.72 m, a = 0.44 m / MA 0.2 0.1 P I 0 0 1 2 3 4 5 6 7 2 / MW 1 tot P 0 0 1 2 3 4 5 6 7 19 x 10 3 -3 2 / m 1 e n 0 0 1 2 3 4 5 6 7 5 / a.u. 107310 a D 0 0 1 2 3 4 5 6 7 5 / a.u. 107315 a D 0 0 1 2 3 4 5 6 7 time / s B. Unterberg, 16th 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-2.053 • Reduced Bt (≤1.9T), plasma limited by inner wall • power threshold 1.6-2.0 MW at 1.3T • Confinement improvement <40% • High frequency ELMs (300-1300 Hz) Ip=235 kA, Bt=1.3 T, R=1.72 m, a=0.44 m (qa=3.7), Ptot=1.6 MW (NBI co-current)

  7. TEXTOR # 107308, t= 2.5 s 0.5 0 -0.5 1 1.5 2 2.5 y Plasma profiles dynamics (High Resolution Multi-Pass TS). • Pedestal mostly manifests itself in density. D Reflectometer covers 0.8<<0.95 Ne Between ELMs Te pe

  8. Turbulence spectrum trough L-H transition . c=41.5 cm c=40 cm Radial scan of ~ 4 cm c=39 cm c=37.8 cm N23 H L H Ohmic NBI co • Quasi coherent mode at f~13kHz is observed after L-H transition. • No mode in L-mode phase.

  9. Spectrum overview vs radius (in Between ELMs). Modes amplitude m~5 m~5 m~19 m~43 • 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]

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

  11. Ambient turbulence in H-mode

  12. Refl. spectrum evolution on ELM time scale • 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.

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

  14. H-mode + RMP

  15. Effect from RMP application 107318, 1.0 kA 107321, 2.5 kA c, min 107322, 4.0 kA L 0.85 0.9 0.95 1 1.05 Y N 107310 (L-mode) 5 D / a.u . a 0 107308 (H-mode) 5 0 107318 (DED 1.0 kA) nELM =560 Hz 5 0 107321 (DED 2.5 kA) nELM = 700 Hz 5 0 107322 (DED 4.0 kA) 5 0 2.36 2.38 2.4 time / s Pedestal degrades with RMP amplitude DED coils layout Reduction of Da ELM burst nELM =360 Hz with RMP amplitude: • pedestal degrades • ELM ampl. decreases • nELM increases The features are the same as observed on diverter machines (JET, DIIID) B. Unterberg et al., PSI Conference 2008 B. Unterberg, 16th European Fusion Physics Workshop, Cork, Ireland, 1-3 December 2009

  16. Spectral characteristics (r=37cm, r/a=0.83) • QC modes both at 13 and 48 and 110 kHz die away when RMP amplitude increases. • The turbulence spectral integral increases with IDEDby ~2 times within 1<IDED<3.75 kA. “13 kHz”

  17. N8 • 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]

  18. Analysis of 13kHz mode in magnetic fluctuations. • Magnetic fluctuations were studied on the pre @ post cursor subject in #107307. • In the view of not regular response in MC statistical analysis was implemented within 1.8<t<2.7 s <=> ~400 ELM crashes. <TELM>~2ms • Two clear peaks: Pre cursor (~-150us) and Post cursor (~1300 us) • Precursoris more localized (FWHMPre=150us)means more regular compare with Postcursor but less representative (N/Ntot~27%) • Post cursoris distributed broader: FWHMPost=500us, and more representative:N/Ntot~40% • Most likely that the rest of magnetic bursts (~40%) are not related with the ELMs. • Deep within 0<t<0.7 ms => nearly no magnetic fluctuations in the beginning of recovery stage D MC TELM Data for 2 poloidal probes 0o and 75o agrees well. <TELM>~2ms <TELM> <TELM> t [s]

  19. Turbulence rotation. RMP influence. • RMP reduces the rotation shear at periphery of H-mode plasmas. • It agrees with pressure profile deterioration observed with TS

  20. 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 withm~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. 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.

  21. Turbulence spectrum. Response on RMP . DED 2.5kA DED 1kA #107318 c [cm] Frequency [kHz] “13 kHz” QC mode degrades with RMP amplitude. Da #107321 c [cm] Frequency [kHz]

More Related