IAEA-CN-116 / EX / 7-2

Transcription

1 ASDEX Upgrade Max-Planck-Institut für Plasmaphysik Active Control of MHD Instabilities by ECCD in ASDEX Upgrade M. Maraschek (), G. Gantenbein (), T.P. Goodman (3), S. Günter (), D.F. Howell (4), F. Leuterer (), A. Mück (), O. Sauter (), H. Zohm (), contributors to the EFDA-JET workprogramme (5) and the ASDEX Upgrade-Team () () Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstr., D Garching, Germany () Institut für Plasmaforschung, Pfaffenwaldring 3, D-7569, Stuttgart, Germany (3) CRPP-EPFL, EURATOM Association, CH-5, Lausanne, Switzerland (4) Euratom Association/UKAEA, Culham Science Centre, Abingdon, United Kingdom (5) see annex of J.Pamela et al., Nucl. Fusion 43 (3) 54 Introduction and motivation Sawtooth tailoring with co / counter ECCD NTM stabilization with co-eccd FIR-NTMs and their triggering with ECCD Summary and future plans th IAEA FEC, Vilamoura, Portugal, -6 November 4

2 Resonant surfaces and MHD modified with ECRH / ECCD #93, 3.99 s deposition q=, (flat or reversed in the centre in adv. scen.): sawteeth, fast particle driven fishbones, (/)-modes sawtooth tailoring, avoidance of NTM trigger q=4/3: (4/3) NTM, ideal (4/3) modes during FIR-NTM artificially trigger / avoid (4/3) FIR-NTM transition q=3/: (3/) NTM stabilisation and suppression of (3/)-NTM ECRH beam ECRH deposition layer, controlled by Bt q=: (/) NTM, (/) classical current driven tearing modes stabilisation and suppression of (/)-NTM (j, ne, Te) profile tailoring for advanced scenarios control of current drive and depostion by Bt and toroidal and poloidal launching angle th IAEA FEC, Vilamoura, Portugal, -6 November 4

3 Sawtooth tailoring with ECRH / ECCD collaboration with T.P.Goodman, O.Sauter (CRPP) normalised sawtooth period τ τo HFS co-eccd inversion radius complete stabilization LFS ECR deposition in ρpol co-eccd: - stabilisation / full suppression outside inversion radius - destabilisation for on-axis explainable with critical shear criterium: dq/dr r/q > (dq/dr r/q)crit pure heating (= 5% co and counter-eccd): - similar behaviour as for co-eccd, but less pronounced - addtional stabilisation when (/) mode is directly hit 7 HFS ctr-eccd LFS normalised sawtooth period τ τo inversion radius complete ST prevention counter-eccd: - stabilisation for on-axis - effect on (/) mode plays an additional role ECR deposition in ρpol PNBI = 5MW, PECCD.4MW th IAEA FEC, Vilamoura, Portugal, -6 November 4 A.Mück, EPS3, St.Petersburg A.Mück, PPCF, to be subm.

4 High power NBI experiments: NTM avoidance at high βn =.8 collaboration with T.P.Goodman, O.Sauter (CRPP) #735 co-eccd #738 counter-eccd NBI *ECR βn (3/)-NTM amplitude ECE time (s) W e6 8e6 4e ev 4 sawtooth tailoring less clear with higher PNBI MW off-axis co-eccd no NTM during ECCD no sawteeth, first large sawtooth triggers on-axis counter-eccd fishbone triggered NTM during ECCD (/) mode further outside, no big seed-island higher PNBI = MW to reach NTM-threshold βn.8 fixed by βp feedback NTM avoidance achieved th IAEA FEC, Vilamoura, Portugal, -6 November 4 A.Mück, EPS3, St.Petersburg

5 (3/)-NTM stabilisation with co-eccd at βn =.6 PNI =.5MW * PECCD = MW (3 gyrotr.) MW 5 #93 5 BT complete (3/)-stabilisation T βn, Beta Normalized B[a.u.] (3/) NTM amplitude time (s).4. complete stabilisation at βn =.6 with PECCD = MW and PNBI =.5MW βn / PECCD =.6/MW βn increase with more PNBI not considered even higher βn achievable (re-excitation) th IAEA FEC, Vilamoura, Portugal, -6 November 4

6 Influence of the deposition width on the (3/)-NTM stabilisation I/d [ka/m] 8 I/d [ka/m] 6 4 W min / Wsat W min / Wsat tor angle [deg] narrow depostion: I / d = current density maximal for -5 (TORBEAM) full stabilisation with reduced PECCD / PNBI possible higher βn achievable at stabilisation ( βn / PECCD, βn / (PECCD/PNBI) ) W > d reduces the stabilisation efficiency ECCD modulated by mode (only O-point) might be required for ITER (modulation experiments will be performed in 5) Jcd [MA/m^] phi = - deg IECCD = 8 ka d =. cm jmax =.7 MA/m phi = -5 deg IECCD = 4 ka d =. cm jmax =.56 MA/m phi = -5 deg IECCD = 9. ka d =.46 cm jmax =.7 MA/m phi = -.5 deg IECCD = 3. ka d =.4 cm jmax =.9 MA/m (Bt = const, ρdep not corrected) ρ p th IAEA FEC, Vilamoura, Portugal, -6 November 4

7 (/)-NTM stabilisation with co-eccd at βn =.3 MW 5 PNI = MW * PECCD =.4MW (4 gyrotr.) 5 #9454 BT complete (/)-stabilisation T - -. (/) NTM amplitude (n=) βn, Beta Normalized time (s).5 B [a.u.] 5-5 V. Locked Mode signal -. stabilisation at βn =.3 [.9] with PECCD =.4MW [.9MW], PNBI = MW [6.5MW] βn / PECCD =.64/MW [./MW] stabilisation of the (/) NTM requires more power (βp,marg, less current drive) current density I/d is the figure of merrit for both NTMs faster unlocking of (/)-NTM injection in the O-point of the locked mode works th IAEA FEC, Vilamoura, Portugal, -6 November 4

8 Nonlinear modelling allows separation of different terms relative island width w/a..5 shift of deposition radius during Bt-scan at 3 cm/s (3,), (6,4) and (,) component togther (,) comp. (3,) comp. time dependent Fokker-Planck code to calculate jeccd(r,t) [G. Giruzzi et al.,nf,39(),7(999)] nonlinear D-MHD (circular cylinder) [Q. Yu and S. Günter, POP,7,3 ()]...5. time [s] typically -% of plasma current driven at resonant surface (Fokker-Planck-Code) Modelling of DC co-eccd with scan of deposition and Fourier analysis : helical current ((3,)-comp.) and -effect ((,)-comp.) are of similar importance complete stabilisation only due to synergy of both effects th IAEA FEC, Vilamoura, Portugal, -6 November 4

9 FIR-NTMs - a general NTM behaviour for βn >.3 collaboration with D.F.Howell (UKAEA) W W.3 smooth open = ASDEX Upgrade full = JET even n -.. #87 n=3 amplitude. f (khz). 4 (4,3) odd n (3,). FIR 7 5. (,) amplitude (,) β N,onset t (s) common behaviour of FIR-NTM for βn >.3 for JET and ASDEX Upgrade stabilility of required coupled ideal (4/3)-mode (high p, low q infernal mode) ELMs have a similar effect at JET for βn >.9 for low Bt, low q95 presence of q= surface modifies behaviour in improved H-mode th IAEA FEC, Vilamoura, Portugal, -6 November 4

10 Triggering / suppressing of FIR-NTMs with ECCD 5 NBI heating power [MW] (4/3) burst 3 ECRH power [MW] 5 #7955, SXR:C: β N 5 w [a.u.] w [a.u.] ctr-eccd (3,) mode amplitude co-eccd (3,) mode amplitude time (s) f [khz] time [s] triggering of ideal pressure driven (4/3) mode by q-flattening with ECCD (ideal: growth time, duration; p, q - dependence as for infernal modes) FIR behaviour of NTM at lower / higher βn can be triggered / suppressed th IAEA FEC, Vilamoura, Portugal, -6 November 4

11 Present status and plans for the future feed-forward Bt - scan feedback stabilisation: () realtime detection of (m/n) mode, its localisation and deposition of the ECCD () feedback loop for the resonant surface (ρeccd = ρntm) (3) steerable ECCD launchers and tunable gyrotrons immediate reaction at still small island efficiency? PNBI increase to raise βn keep ECCD on q-surface without an NTM ultimate goal is not only removal, but avoidance of NTM feedback loop on ρeccd = ρ(q) with equilibrium q-profile seed-island avoidance (such as sawteeth and/or fishbones) co-eccd to "prevent" bootstrap hole at the resonant surface global tailoring of the j-profile ( effect) or the ne-profile (bootstrap is driving term via ne) to reduce drive for MHD mode th IAEA FEC, Vilamoura, Portugal, -6 November 4

12 Summary and outlook local co / counter-eccd has been shown to be a powerful tool to control core MHD narrow deposition layer, well controlable deposition and width sawtooth tailoring at intermediate PNBI, NTM avoidance at higher PNBI NTM stabilisation with narrow deposition reduces power requirements (βn/peccd) trigger and suppress FIR-NTM phases physical understanding Outlook: application of feedforward technique: deposition width and modulation experiments with broad deposition, extension towards more general scenarios realtime feedback control with increased ECCD power and control capabilities will be addressed in 5 for stabilisation and avoidance th IAEA FEC, Vilamoura, Portugal, -6 November 4

13 Dependence of the sawtooth frequency on the NBI selesction SXR C3 #667 W/m** 3 variation of tangency radius governs the fast particle distribution from NBI fast particle stabilisation sawtooth period [ms] S3 S7 S4 S8 S S6 S S5 time (s) SXR B # time (s) variation in the particle energy between kev and 6 kev has an additional impact significantly different deposition profiles for different sources correction for sawtooth frequency required! th IAEA FEC, Vilamoura, Portugal, -6 November 4

14 Power dependence of the sawtooth behaviour MW.6 MW.4 MW.8 SXR B 3. SXR B co-eccd 3. SXR B 3. co-eccd co-eccd ρpol ~ time (s) ρpol ~ time (s) time (s) #673 #673 #679 W/m** 3 W/m** 3 th IAEA FEC, Vilamoura, Portugal, -6 November 4 W/m** 3 Frequency [Hz] W/m SXR B ECR variation of (/) ampl. with constant sawteeth (/) mode survives role of the (/) mode 5 ρpol~. # signal: B, index: time (s)

15 Stabilisation of neoclassical modes by external current drive in the O-point of the islands P ECRH Experiment ECRH Power (not calibrated) #8 ac: 4kW dc: 8 kw W 5 w /a.. Numerical modelling odd n db dt even n β N n=,3 amplitude n= amplitude time (s) H. Zohm et al. NF 39 (999) modulated CD ECCD non-modulated CD I /I =.4 ECCD P t= w ECCD /a = (including heat transport and current diffusion) Q. Yu, S. Günter, PPCF 4 (998) 977 t / τ R modulated ECCD in O-point: PECCD/PNI 4-8%, 4% βn recovery with mode reduction Stabilisation is also effective for non-modulated current drive th IAEA FEC, Vilamoura, Portugal, -6 November 4

16 Bt - scan for resonance ECRH (MW) NBI/ (MW) Beta normalized with NTM Beta normalized without NTM n=, Mirnov Signal Shift of EC resonance (cm) Time (s) resonance scanned with 4 kw co - ECCD (+heating) shift of deposition of ECCD: 8 cm shift of mode during scan: cm shot to shot variation of mode location cm resonant intervall 4cm same order as island half width and deposition width th IAEA FEC, Vilamoura, Portugal, -6 November 4 4cm

17 amplitude [a.u.] amplitude [a.u.] amplitude [a.u.] Co / Counter current drive and heating alone ASDEX Upgrade #57, MOD:EvenN, f=khz, smooth=8 co-injection complete stabilisation time [s] ASDEX Upgrade #538, MOD:EvenN, f=khz, smooth=8 counter-injection 45 % reduction time [s] ASDEX Upgrade #345, AUGD:MOD:EvenN, f=khz,smooth=8 pure heating weak mode reduction time [s] comparison between co- and counter-eccd effect(co) = heating + ECCD effect(counter) = heating ECCD heating and ECCD result in a comparable stabilizing and destabilizing heating alone not sufficient to stabilize mode at a given ECRH power th IAEA FEC, Vilamoura, Portugal, -6 November 4 #345 E+7 ECRH Power * Heating Power (NBI) 5E+6 shift of EC resonance Beta Normalised n= amplitude time (s) application of magnetic field ramp ECRH: -5, +5, for co-eccd, counter-eccd, heating W cm

18 FIR-NTMs by nonlinear mode coupling with(m+,n+) modes and (,) mode even n f (khz) #87 n=3 amplitude. (,) amplitude odd n (4,3) (3,) (,) t (s) presence of both (m+/n+) mode and (/) mode required (3,) amplitude (a.u.) f (khz) (4,3) (3,) t (s) # 68.5 f(3,) f(3,) phase locked resonance required th IAEA FEC, Vilamoura, Portugal, -6 November 4 A.Gude, Nucl. Fusion 4 () 833

19 General idea of a feedback loop for NTM stabilisation NTM detection mode numbers ECCD and loop off ECCD and loop on NTM amplitude =, βn - max, WMHD = max,... ECCD localisation mode localisation localisation from calibrated / improved equilibrium mode phase first guess launch angle of ECCD ρntm = ρeccd ECCD modulation launch angle Rplasma, Bt at DIII-D ECCD deposition meas. by ECE TORBEAM calculations for "first guess" for new scenarios ECCD modulation available trigger th IAEA FEC, Vilamoura, Portugal, -6 November 4

20 Newly developed tools for the stabilisation (SENSOR) PNI #93 W.5E+7 E+7 PECCD 5E+6 MOD:EvenN 4 amplitude from FFT tracing RVE:MHD low pass from ECCD trigger time (s) V 8 4 EvenN Trigger detection of odd n ((/)-NTM, but (/) also) and even n ((3/)-NTM) diagnostic upgrade provides realtime n=, n=, n=3 detection detection of localisation of the mode and ECCD via realtime ECE / SXR th IAEA FEC, Vilamoura, Portugal, -6 November 4

21 .3. Detection of mode and ECCD on ECE (SENSOR) cut-off. Shot #74, NTM and ECRH position determination by correlation analysis Noise: ELMs NTM position detection ECRH position detection ECRH position detection ECRH position simulation NTMs can be directly measured from high time and radial resolution ECE Radius [m] ECCD modulation (9%) mode can be detected at the same time on ECE input quantities for NTM feedback stabilisation available.89 NBI Power (MW) ECRH Power (MW) Magnetic Perturbation (a.u.) #74 W 5 5 W high time resolution - realtime capabilities - Toroidal Field T Normalised Beta time (s) th IAEA FEC, Vilamoura, Portugal, -6 November A.Keller, EPS3, St. Petersburg

22 The new ECRH system on ASDEX Upgrade (ACTOR) power: 4 MW, provided by 4 gyrotrons pulse length: sec frequency: 5 / 4 GHz as a -f-gyrotron 5 / 7 / 7 / 4 GHz as a step tunable gyrotron change of frequency between pulses launcher: feedback controled deposition via poloidal launching angle toroidal angle can be set between pulses heating and current drive, in particular for advanced tokamak regime suppression of tearing modes control of transport and pressure profile th IAEA FEC, Vilamoura, Portugal, -6 November 4