Dynamic Resonant Error Field Correction with C-COIL and I-COIL in the DIIID device

Transcription

1 Dynamic Resnant Errr Field Crrectin with C-COIL and I-COIL in the DIIID device M. Okabayashi, M.S. Chance, R, Hatcher, J. Manickam P P P L, J. Bialek, A.M. Garfal, G.A. Navratil, H. Reimerdes, C lumbia U., M.S. Chu, G.L. Jacksn, T.H. Jensen, R.J. La Haye, J.T. Scville, E.J. Strait, G A, R.J. Jayakumar, LLNL, D.H. Edgell, FAR -T E C H, Inc "Active C ntrl f MHD S tability: E xtensin t the B urning P lasma R egime " University f Texas-Austin Nvember 3-5,2003

2 RWM Feedback System Has Been Imprved with New Hardware: :Newly-installed I-cils, New ff midplane Sensrs, SPA upgrade and PCS upgrade Cils being installed in DIII D New I-cil x New Sensrs Existing C-cil

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4 Dynamic Errr Crrectin Prcess Maintains Identical Plasma Rtatin by use f Either C-Cil r I-Cil Ip betan/(2.4li) C-cil cur. (ka) I-cil cur (ka) Plasma Rtatin km/s) Full C-cil crrectin Full I-cil Crrectin

5 I-cil at Dynamic Resnant Errr field Crrectin is as Effective as C-Cils Maintaining High Plasma Rtatin

6 Dynamic Errr Field Crrectin with I-Cil Maintains Plasma Rtatin by Requesting Different Level f Current fr Different Cil Cnnectin I-cil current needed fr resnant errr field cmpensatin (amplitude: ka) cil current limit Disrupted with RWM time cnstant 0.0 Rtatin (km/s) DIII D N ATION AL FU S ION FAC ILITY Upper/Lwer I-cil cnnectin angle

7 I-cil Feedback Has Opened Higher bn Access Even If the Rtatin is Reduced during Discharge Imprved Time Respnse bserved in the Cntrl n ELM Induced RWM b / n.wall n b n sensr (G) db(g) ideal wall limit C b 1.0 Gp/Gd=40/20 q=2 MARS predictin Gp/Gd=40/80 Gp/Gd=40/0 Gp/Gd=40/40 I-cil Gp/Gd / / / / N FB D-alpha ªzer rtatin C-COIL: Gp/Gd=57/0 time rt (km/s) n wall limit 0.0 n feedback Rtatin (km/s) data with strng Ip ramp lw-q (q95ª3.0) 2.4li plasma DIII D N ATION AL FU S ION FAC ILITY C b = n.wall (b n - b ) n ( b ideal.wall n.wall - b ) n n

8 Dynamic Resnant Errr Field Crrectin Prcesss with Feedback High gain limit (K -> ) RESONANT AMPLIFICATION FACTOR <pl Apl K FEEDBACK GAIN Berrr> I_errr Bprepr> I_prepr } -initial guessing - Bfb> I_fb? Estimated Ttal Current fr Errr Cmpensatin = I_fb + I_prepr = -<pl Berrr> <pl Bfb> I_errr + I_prepr * e + 1/(K*Apl) [...] Better cupling between the feedback and plasma -> lwer crrectin current What is pssible cupling mechanism?

9 Pssible frmulatin fr cuplings : Trque in the tridal directin: Frce in tridal directin F = ( f d j pl x B ext ) f dj pl,n = s db pl. f.- (1/R) f db pl. q dj pl,q = f db pl.n.- (1/R) n db pl. f = - f [ db pl. q B ext.q + db pl. n. B ext.n ] Assumptin: - db pl. f. ª 0: Lcal Trque Integrated ver the surface: Ú F f R ds Vlume integrated trque Phase shift : negative feedback autmatically minimizes the shift

10 m=2 x r m=1 f m=3 m=5 m=4

11 dbn n : q= 2-, 2+,3, 4, 5

12 Mde Structure

13 Bn Field Pattern n q =3 Surface C-cil plidal directin I-cil Plasma mde 0.0 tridal directin (degrees) 360 * 0 degrees in the uter mid-plane

14 Lcal Trque Pattern n Surface: C-cil ( t= 2500 ms) I-cil (2600 ms) q= plidaldirectin q=3 tridal directin tridal directin

15 Nrmal and plidal field by C-cil Nrmal Field Plidal field C-cil Plasma B*B

16 Nrmal and plidal field by I-cil(240deg) Nrmal Field Plidal field I-cil Plasma B*B

17 Trque arund q=3 Surface by I-cil with Actual I-cil Current at t=2600ms Matches with Trque with C-cil by Actual cil current at 2500ms C-cil q=2(-) I-cil q=4 q=2(+) q=5 Full C-cil crrectin Full I-cil Crrectin q=3 Tridal angle relative t the Mde and applied field q=edge Tridal angle relative t the Mde and applied field

18 Trque by I-cil Matches with C-cil Trque arund qª 3 Surface Trque with I-cil with C-cil Df phase difference (degrees) edge Df : Phase Shift between Trque Estimated with C-cil curent at 2500 ms and I-cil current at 2600 ms and I-cil (degrees)

19 Dynamic Errr Field Crrectin with I-Cil Maintains Plasma Rtatin by Requesting Different Level f Current fr Different Cil Cnnectin I-cil current needed fr resnant errr field cmpensatin (amplitude: ka) cil current limit Disrupted with RWM time cnstant 0.0 Rtatin (km/s) DIII D N ATION AL FU S ION FAC ILITY Upper/Lwer I-cil cnnectin angle

20 Effective Averaged Field with Varius Upper / Lwer I-cil Cnnectin Can Be Estimated Using Surface Averaged Trque db eff q-edge q=5 q=4 q=3 q= Upper/Lwer I-cil cnnectin (degrees) Ú db ext db ds db = n.pl eff db ds n.pl Ú Current fr dynamic crrectin 1 /db eff

21 I-cil current needed fr resnant errr field cmpensatin (amplitude: ka) Resnant Errr Field Cmpensatin is Mst Effective when I-cil Field Cuples with RWM Structure at q=4 - I-cil pitch was scanned by varying upper/lwer I-cil cnnectin cil current limit Disrupted with RWM time cnstant Estimate with the cupling at q=4 0.0 Estimated I-cil cupling t RWM Bn (gauss/ka) 1.0 q-edge q=3 q=4 q= q= I-cil cnnectin angle 400 DIII D N ATION AL FU S ION FAC ILITY residual errr assumed at 45 deg.

22 I-cil Feedback Has Opened Higher bn Access Even If the Rtatin is Reduced during Discharge Imprved Time Respnse bserved in the Cntrl n ELM Induced RWM b / n.wall n b n sensr (G) db(g) ideal wall limit C b 1.0 Gp/Gd=40/20 q=2 MARS predictin Gp/Gd=40/80 Gp/Gd=40/0 Gp/Gd=40/40 I-cil Gp/Gd / / / / N FB D-alpha ªzer rtatin C-COIL: Gp/Gd=57/0 time rt (km/s) n wall limit 0.0 n feedback Rtatin (km/s) data with strng Ip ramp lw-q (q95ª3.0) 2.4li plasma DIII D N ATION AL FU S ION FAC ILITY C b = n.wall (b n - b ) n ( b ideal.wall n.wall - b ) n n

23 Direct Feedback is Observable n Feedback Respnse t ELM induced RFA_RWM Fast Respnse Cmpnent Amplitude Impact n after ELMs Feedback n A sensr signal (MPID067U) D-alpha 1200 time (ms) 1600 DIII D N ATION AL FU S ION FAC ILITY

24 Fast Respnse Cmpnent Amplitude Befre Feedback Feedback n ELMs A sensr signal (MPID067U) D-alpha 1250 time (ms) time (ms) 1350

25 Fast Respnse Cmpnent Amplitude Feedback n Feedback n A sensr signal (MPID067U) D-alpha 1300 time (ms) time (ms) 1450

26 Fast Respnse Cmpnent Amplitude Feedback n Feedback n A sensr signal (MPID067U) D-alpha 1450 time (ms) time (ms) 1550

27 Feedback with I-cil Imprved the Time Respnse up t wt ª 3 w C-Cil I-Cil N Feedback N Feedback Gp/Gd=57/57 FB n 1250 time(ms) time(ms) N feedback Gp/Gd=40/40 FB n db (G) C-cil I-cil freq(khz) /195/826/820.ai DIII D N ATION AL FU S ION FAC ILITY

28 SUMMARY Dynamic Resnant Errr Field Crrectin with C-COIl and I-COIL - Identical Impact n Plasma Rtatin - I-cil Cnnectin Flexibility -> Parametric Dependence Lcal Trque Hypthesis Prvides a Cnsistent Interpretatin I-Cil Imprved Time Respnse, better Cntrl n RFA& RWM

29 I-Cil feedback Imprved the Respnse arund wt = Stable RWM respnse t ELM induced n=1 perturbatin w H-alpha MPID averaged c-cil I-cil freq((khz) freq((khz) C-cil: Gp/Gd=57/ I-cil : Gp/Gd=40/ Next Issue: the cntrl at wt = 5-10 regime with feedback ptimizatin and further hardware imprvement w QQ/197/822/cmp/FFT.ai

30 Fast Respnse f Feedback is Taking Place with I_cil_FB ª 1 ka ( < 1gauss) 4.0 Gp/Gd= 40/40 40/0 40/20 Feedback Requested Current (ka) Cmmn fr varius gain setting Fast Feedback Fine Tuning by Dynamic Errr Field crrectin Ttal errr field Preprgrammed errr field crrectin phase / / / / time(ms) 1600 ffset-&angle-subtractin/#2.ai DIII D N ATION AL FU S ION FAC ILITY

31 Direct Feedback Cmpnent is ª 1kA ( 1 gauss n plasma) ms ms ms ms 1 ka 2 ka DIII D N ATION AL FU S ION FAC ILITY