1. Page 1 Sun Hee KIM, Plasma Operations/POP Corsica simulation of ITER hybrid mode operation scenario S.H. Kim and T.A. Casper ITER Organization, St Paul lez Durance, France Acknowledgement : LLNL, ITER/Monaco R.H. Bulmer, L. LoDestro, W. Meyer and D. Pearlstein (LLNL) – Corsica collaboration J. Garcia (CEA), M. Henderson (ITER), C.E Kessel (PPPL) and T. Oikawa (ITER) – useful discussions

2. Page 2 Sun Hee KIM, Plasma Operations/POP Outline 1.Introduction 2.Source modules for Corsica simulation 3.Backing out simulation of ITER hybrid mode operation 1.Reference hybrid mode simulation (33MW NB & 20MW EC) 2.Varying simulation conditions 3.Pre-magnetization 4.Various HCD schemes 5.Ramp-down shape evolution 4.Forward simulation of ITER hybrid mode operation 5.Summary and perspectives

3. Page 3 Sun Hee KIM, Plasma Operations/POP Introduction 1.Simulations of ITER hybrid and steady-state mode operations are requested to support several tasks for resolving ITER physics and engineering issues. 1.Feasibility of achieving physics goals, such as Q and plasma burn duration 2.Heating and current drive requirements, and profile tailoring 3.Plasma control system, coils and power supplies 2.Corsica provides a self-consistent free-boundary plasma evolution with transport and sources, using a fully implicit coupling scheme. 3.Realistic source modules (NB/EC/LH/IC) are recently either upgraded or added, and their operating parameters are determined reflecting recent ITER design changes. 4.Corsica is ready to support ITER PCS (as a practical tool for validating PCS concepts) and IM (as a candidate for plasma simulator) projects.

4. Page 4 Sun Hee KIM, Plasma Operations/POP Corsica source modules I 1.NB : Nfreya, orbit following MC code for heating and current drive, an existing module in Corsica package 2 Beam geometries and effective beam divergence for Nfreya have been computed using new design parameters (T. Oikawa) The poloidal angle (on-axis,ref,off-axis) = (-2.819,-2.306,-3.331) [deg], toroidal angle = 9.426 [deg], beam height = 1540[mm] and width = 580 [mm] 2.EC : Toray-GA, ray-tracing wave code Existing module was out of date. Recent versions, v1.6 (NTCC) and v1.8 (GA, R. Prater) are newly implemented. We are currently using Toray-GA v1.8. 5 EC launcher geometries and effective wave divergences have been computed using new design parameters (M. Henderson) 3 EL, co-EL (upper, 1), counter-EL (middle, 2) and co-EL (lower, 3), and 2UL, USM (4) and LSM (5). Each launchers can deliver 6.67MW. Automatic scan on the poloidal and toroidal angles has been developed to find required mirror angles.

5. Page 5 Sun Hee KIM, Plasma Operations/POP Automatic scan on EC angles Automated suggestion for mirror angles of EL upper Off-axis High J EC P e, EC J EC

6. Page 6 Sun Hee KIM, Plasma Operations/POP Corsica source modules II 1.LH : LSC, ray-tracing wave code, NTCC library, newly added ‘n_parallel’ and ‘tilt angle of the launcher’ have been obtained from TSC ITER simulation setting (C. Kessel). Graphical outputs are suppressed and output values less than 1e-100 are set to zeros. 2.ICRF : Toric, Full wave code, in preparation A version originally used for developing interface is working, but prescribed heat deposition profiles are used in this work. No IC driven current is assumed. ITER will have an official version soon from IPP (discussed with R. Bialto and J. Rice)

7. Page 7 Sun Hee KIM, Plasma Operations/POP Realistic source profiles NB33/EC20/LH20/IC20 case NB : 33MW, off-axis EC : 20MW, off-axis, election heating IC : 20MW, 46MHz (J. Garcia, on-axis P e & off-axis P i ) / 53MHz (on-axis P e & P i ), prescribed heat deposition porifiles, no driven current LH : 20MW, n || =2.2(C. Kessel), far off-axis t=60s

8. Page 8 Sun Hee KIM, Plasma Operations/POP Reference simulation of ITER hybrid mode 1.12.5MA scenario has been developed by tailoring the 15MA scenario (T. Casper) 2.Large bore startup (initially inboard limiter configuration) 3.n e (0,flat-top)=8.5e19 m -3 & n GW ~9.9e19 m -3 4.Zeff(t)~1.7+2.3*(ne0(t0)/ne0(t))^2.6 (V. Lukash) 5.1300s of current flat-top 6.60s ramp-up without pre-magnetization (XPF at about 15s and L-H transition at 40s) 7.210s ramp-down (H-L transition 70s after EOF, no auxiliary power 30s after H-L transition)

9. Page 9 Sun Hee KIM, Plasma Operations/POP Evolution of plasma profiles 1.Coppi-Tang transport model with the coefficients used for 15MA H-mode simulation 2.Te(ped) ~ 3-4keV, ρ tor (ped) ~0.95 3.Be and Ar impurity densities, self-consistently with Zeff(t) 4.33MW of NB (off-axis) & 20MW of EC (2 co-ELs and 1 UL-LSM). Source profiles are calculated at every time-step. 5.Effective sawteeth by increasing the heat conductivities and plasma resistivity inside the inversion radius, when q min <0.97

10. Page 10 Sun Hee KIM, Plasma Operations/POP Evolution of plasma parameters At t=1359s (tEOF = 1360s) 1.Q ~ 9.6 & P α ~ 101MW  high Q (>5.0) with relatively low P aux =53MW 2.H 98 ~ 1.24 & l i (3) ~ 0.75  improved confinement, good for the vertical stability 3.β N ~ 2.5 & β p ~ 0.82  high betas 4.I BS ~ 3.8MA, I NB ~ 2.5MA & I EC ~ 0.4MA  f NI ~ 0.54 (it seems not enough for q>1.0) 5.q(0) ~ 0.98 & q min ~ 0.97  a slightly reversed or flat q profile inside ρ tor ~ 0.4

11. Page 11 Sun Hee KIM, Plasma Operations/POP Evolution of coil currents 1.CS coil currents are well within the coil current limits. 2.PF6 coil current is briefly violating the coil current limit (~19MA at B max = 6.5T without 0.4K sub-cooling ) at SOF. This is OK with UFC criteria. 3.PF2 coil current is violating its lower coil current limit during the ramp-down, due to the shape transition to the outboard limiter configuration (will be shown later). 4.The total flux consumption is well within the limit.

12. Page 12 Sun Hee KIM, Plasma Operations/POP B-field, imbalance current and force limits (Ref.)  PF2 violated B-field, force and imbalance current limits during the ramp-down at about I p ~3.5MA with P aux =0W.  It appears that PCS can handle this with no damages on the system.

13. Page 13 Sun Hee KIM, Plasma Operations/POP Low density/low confinement/no Sawtooth Application of different simulation conditions 1.Low density case (ne(0,flat-top) = 7.0e19 m -3 (n e /n GW ~0.7)  lower W th, H 98, β N, β p, P α, Q and I BS  higher l i, I NB and I EC 2.Low H-mode confinement case Slightly higher L-mode confinement (Coppi-tang coef. 2.5  2.0) and slightly lower H-mod confinement (Coppi-tang coef. 1.10  1.15)  lower H 98, β N, β p and higher l i 3.No Sawteeth case  Very similar to reference simulation except q < 0.97  Slightly different q(0) behaviours At SOF (t=1359s)RefLow dens.Low conf.No ST W th [MJ]361.3296.6 (▼)339.9361.4 H 98 1.2371.1871.1851.238 βNβN 2.5162.1112.3682.517 βpβp 0.8150.6850.7680.815 l i (3)0.7450.787 (▲)0.7410.745 q(0)0.9821.3961.3760.845 q min 0.971 0.9700.969 min(q)0.970 0.845 I BS [MA]3.763.053.573.76 I NB [MA]2.493.222.362.49 I EC /I LH [MA]0.41/-0.50/-0.41/- P α [MW]100.968.592.2101.0 P loss [MW]116.794.3110.7116.7 P aux [MW]52.3052.9452.6452.30 Q9.646.468.749.65 T e (0) [keV]28.7127.0727.3428.97 T i (0) [keV]29.3127.8427.1429.24 T e (0.95) [keV]3.563.723.413.59 Flux(t=7.33s) [Wb]69.89 Flux(SOF) [Wb]-90.22-90.90-93.27-90.22

14. Page 14 Sun Hee KIM, Plasma Operations/POP Central q behaviours (a)Reference case (b)Low density case (c)Low H-mode confinement case (d)No sawteeth case  Effective sawteeth increased the plasma resistivity inside the inversion radius  q(0)>1.0  Large jumps at the start of Sawteeth, due to already slightly reversed q profiles (a)(b) (c) (d)

15. Page 15 Sun Hee KIM, Plasma Operations/POP Premagnetization At SOF (t=1359s)refPre-mag20Pre-mag40 W th [MJ]361.3361.5361.4 H 98 1.2371.238 βNβN 2.5162.5172.518 βpβp 0.815 l i (3)0.7450.7430.738 q(0)0.9820.9751.041 q min 0.9710.9700.974 min(q)0.970 0.974 I BS [MA]3.763.773.78 I NB [MA]2.49 I EC /I LH [MA]0.41/- P α [MW]100.9101.0 P loss [MW]116.7116.9116.8 P aux [MW]52.3052.4152.30 Q9.649.639.65 T e (0) [keV]28.7128.9129.05 T i (0) [keV]29.3129.2729.10 T e (0.95) [keV]3.563.593.61 Flux(t=7.33s) [Wb]69.8949.6929.50 Flux(SOF) [Wb]-90.22-110.25-130.23 Avoiding CS coil lower limits (consuming less flux) 1.Early H&CD or large bore start-up 2.Modified shape evolution (flux consumption re- distribution) Avoiding PF coil upper limits (consuming more flux) 1.Late H&CD or small bore start-up 2.Slow current ramp 3.Modified shape evolution 4.Application of premagnetization (either 20Wb or 40Wb)  Very similar plasma parameters with the reference simulation  Different initial flux state, but similar flux consumption  Different coil current evolutions

16. Page 16 Sun Hee KIM, Plasma Operations/POP Coil current and flux state evolution Pre-magnetization using CEQ package in CORSICA PF6 coil current limit is avoided with premagnetization Shift of the flux state, no additional flux consumption

17. Page 17 Sun Hee KIM, Plasma Operations/POP Application of various HCD schemes At SOF (t=1359s) Ref NB33/EC20 NB33/EC40NB33/EC20 /IC20 NB33/EC20 /LH20 NB33/EC20 /LH20/IC20 EC40/LH20EC40/IC20 W th [MJ]361.3389.0391.2390.0416.4373.4379.7 H 98 1.2371.2641.262 1.2841.2531.263 βNβN 2.5162.7092.7222.7122.8882.5002.545 βpβp 0.8150.8770.8810.8800.9370.8100.807 l i (3)0.7450.7230.7150.6220.5920.6550.722 q(0)0.9821.0350.9591.2191.3190.972 q min 0.9710.9870.9701.0871.2090.9700.971 min(q)0.9700.9860.9591.0871.2080.9700.971 I BS [MA]3.764.094.104.304.654.063.95 I NB [MA]2.492.652.622.682.72-- I EC /I LH [MA]0.41/-0.82/-0.41/-0.41/0.900.41/0.890.82/0.900.82/- P α [MW]100.9110.7115.7111.6124.7102.5108.4 P loss [MW]116.7142.9148.7143.9173.8123.7130.2 P aux [MW]52.3072.6472.6572.6492.3159.99 Q9.647.637.977.696.768.538.93 T e (0) [keV]28.7131.6131.4331.3232.7429.8530.31 T i (0) [keV]29.3130.9631.9630.6833.0529.4030.38 T e (0.95) [keV]3.563.843.833.944.043.773.70 Flux(SOF) [Wb]-90.22-82.91-84.69-74.79-70.87-87.79-96.35 1.53MW (ref) 2.73MW (ref + 20MW) 3.93MW (ref + 40MW) 4.60MW (no NB, 2*P EC )  LH  lower l i, q>1.0  Higher I ni  lower flux consumption  Higher power  higher I BS, P α and lower Q  No NB (2*P EC ) cases similar to the reference simulation

18. Page 18 Sun Hee KIM, Plasma Operations/POP q profile evolution & Flux consumption Higher non-inductively driven current and heat deposition  higher q values with LH driven off-axis currents, q>1 until the end of flat-top  less flux consumption and resulting modifications on coil current evolutions Higher power but less driven current (EC40/IC20 case)  more flux consumption t=1359s

19. Page 19 Sun Hee KIM, Plasma Operations/POP Ramp-down shape evolution Application of different shape evolution during the ramp- down phase  No violation of coil current, field, force and imbalance current limits  Difficulties on positioning the sources (too peaked current profile)  Limited or diverted configuration ?

20. Page 20 Sun Hee KIM, Plasma Operations/POP Forward simulation of the reference case  Forward simulation has been done using the reference coil current obtained from a backing out simulation (I CS1 = I CS1U +I CS1L, I PF6 is OK with UFC criteria, PCS might handle I PF2 @ I p ~3.5MA with P aux =0W).  Coil voltages are computed using the ITER controllers (JCT2001 + VS1) and power supply models. 1 2 3

21. Page 21 Sun Hee KIM, Plasma Operations/POP Voltage evolution  Saturation voltage per turn is used for slow controller, whereas VS1 uses the total saturation voltage, 6kV.  Each coil and saturation voltages are multiplied by its coil turns for plotting (might be not exact)

22. Page 22 Sun Hee KIM, Plasma Operations/POP Summary and perspectives 1.ITER hybrid operation scenario has been simulated using Corsica and realistic source modules.  Further study on diverse ramp-up ramp-down conditions  Study optimum combination of HCD for achieving q>1 condition 2.Additional source modules  Official version of Toric  IC module in Accome 3.Pedestal modelling  A pedestal model based on stability analysis 4.ITER steady-state operation scenario modelling  Development of steady-state operation scenarios  Study physics issues related to the steady-state operation and ITBs  Define requirement for ITER H&CD systems 5.Support ITER PCS and IM

23. Page 23 Sun Hee KIM, Plasma Operations/POP Additional slides 1.0

24. Page 24 Sun Hee KIM, Plasma Operations/POP Improved Corsica simulation capabilities 1.Realistic source calculations for NB/EC/IC/LH 2.Electron, ion and impurity density profiles are self-consistently prescribed with the evolution of effective charge and alpha particle transport. 1.Zeff(t) ~ 1.7+2.3*(ne0(t0)/ne0(t))^2.6 (V. Lukash) 2.However, alpha particle transport introduces a modification to the quasi- neutrality condition used when the density profiles are prescribed. This has been resolved in an iterative way. 3.A feedback control capability for the plasma energy confinement corresponding to the H-ITER98(y,2) scaling law during H-mode phase (useful ?) 4.Effective sawteeth to avoid triggering sawteeth during the internal iteration. 1.A flat or reversed q profile can still stay very close to the sawteeth triggering criterion (q min <0.97), even right after triggering a sawtooth. Pivoting around ρ inv. 5.Premagnetization capability using CEQ (Constrained Equilibria) package in Corsica. 1.0

25. Page 25 Sun Hee KIM, Plasma Operations/POP Ramp-down shape evolution - limits No violation of coil current, field, force and imbalance current limits