Physics and operational integrated controls for steady state scenario

1. Physics and operational integrated controls for steady state scenario E. Joffrin, J.F. Artaud, O. Barana, V. Basiuk, C. Bourdelle, S. Brémond, J. Bucalossi, F. Clairet, L. Colas, Y. Corre, R. Dumont, A. Ekedahl, G. Giruzzi, M. Goniche, F. Imbeaux, F. Kazarian, L. Laborde, D. Mazon, P. Monier-Garbet, P. Moreau, P. Maget, B. Pégourié, Y. Peysson, F. Rimini, F. Saint-Laurent, E. Tsitrone, J.M. Travere, F. Turco • Outline: • Stationary scenario for plasma control in TS. • Profile control experiments • Integration of controls for steady state scenarios

2. Advanced steady state tokamak regime Advanced tokamak scenario demands the combination of challenging conditions:  bN . H >8 and Iboot/Ip>50% • High pressure & bootstrap current: • Steady state long duration discharges: • High degree of control over q & P profiles:  Duration >> tR & power handling  Control broad q & P profile Using actively cooled plasma facing components and non-inductive current drive, Tore Supra can address 2 & 3 • Objective: achieve integrated stationary scenario with • Active profile control • Active control of local heat flux on PFCs • Duration: >>tR & ~ thermal constant of all components

3. PLOSSSSEP TS-2004 TS-2005 0.12 ITER 0.1 0.08 Long Pulse (2003) 0.06 JET 1GJ 0.04 0.02 0 10 100 1000 Pulse duration (for 80% of the energy content) Tore Supra operational domain for stationary scenario Tore Supra produces long discharges with high level of RF power (LH & ECCD current drive and ICRH electron heating) 1- Using actively cooled PFC components, Tore Supra has developed pulse length close to 400s (>1GJ). 2- Recent progress in total injected power for times exceeding 60s has extended the domain in PLOSS=Pconv+ Pcond comparable to ITER when normalised to the surface of the separatrix. Profile control experiments can be appropriately developed in discharges lasting more than 10tR ~60s

4. 36182 (BT=3.7T, qedge=8) PFCI & PLH [MW] 1.5 3 1.0 2 Ip [MA] 1 0.5 PFCE [MW] Teo [keV] 6 4 <ne> [x1019 m-3]=0.65 nG 2 ILH [MA] 0.4 0.3 0.2 Vloop [V] Iboot [MA] 0.1 0 10 20 30 40 50 60 70 Time [s] Integrated stationary scenario for plasma control schemes Over 60s duration (tR~5s) 6MW / ~400MJ 1- Using 2 LH coupler and 3 ICRH antenna and 2 gyrotrons and actively cooled components 2- WTH~ 1.3 WITER-L at bp~1 and 65% n/nG 3- e-ITB formation with ECCD q profile change From CRONOS + HXR t=30s 8 4- 85% non-inductive: Iboot=20% ; ILH=65% 6 JLH x10 [MA/m2] 4 q 2 1 1 0

5. Suprathermal electrons local emissivity profile 3000 BT = 3.33 T 2500 60-80 keV energy band . str . s) 2000 Counts / (mm 1500 1000 HXR width 500 0 0 0.2 0.4 0.6 0.8 1 Plasma normalised radius Real time sensors for profile control and long pulses operation 1- Real time thermographic system 8 Cameras monitors all 3 ICRH antennas, all 2 launchers and the toroidal pumped limiter 2- Real time Hard X-ray diagnostic Emissivity profiles computed in real time every 16ms and representative of the LH deposition profile LH-Launcher 3 HXR diagnostic 38 viewing lines

6. 35588 (BT=3.7T ; <ne>=1.3.1019 m-3) 35579 (BT=3.7T ; <ne>=1.3.1019 m-3) Ip [MA] Ip [MA] 0.6 0.2 0.2 0.6 VLoop [V] 0.1 0.3 0.1 0.3 VLoop [V] 0.0 0.0 3.0 PLH [MW] PLH [MW] n// 2.0 1.0 2.0 n// 1.5 1.0 HXR profile width HXR profile width 0.4 0.40 0.35 Request 0.35 Request 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 Time [s] Time [s] Plasma profile control: preliminary experiments LH-power deposition control profile is best demonstrated at low density (n=30%nG) n// of LH-wave HXR width LH power HXR width Both n// and LH-power can be used to broaden the current deposition profile

7. #36133 CRONOS 4 t=12s t=22s t=33s 2.0 JW [MA/m2] 2 PLH [MW] 1.5 0 1.0 Feedback window JLH [MA/m2] 0.8 0.5 0.6 IP [MA] 0.0 0 1.0 n// Target waveforms 2 HXR width PLH IP n// 1.5 primary VLoop=60mV 0.4 width HXR 0.1 0.05 VLoop [V] 0 -0.05 0 10 20 30 40 50 60 70 Time [s] LH deposition profile control at constant Vloop Previous experiment show that the remaining ohmic current plays a role in plasma core: The effect of the ohmic current profile can be minimised by the control of the boundary flux

8. CRONOS r/a=0 JTOT 6 2.0 Te [keV] 5 4 1.0 JLH r/a=0.3 300kW ECCD Johm Jboot JFCE qo 2.0 0 0.5 1.0 r/a r*T (x100) 1.5 qmin 1.0 57 58 59 60 Time [s] ECCD and n// as potentials actuator for ITB control Stationary scenario can develop higher confinement mode with Te oscillation: O-regime With LH-wave index n// With ECCD Current balance at 59s [MA/s] 8Hz n// 4.5Hz • Confirm that local current is an adequate control parameter for stabilising the O-regime. • Local ECCD power deposition or n// can play this role Giruzzi et al. PRL 2005

9. Analysis of RF heat flux sources onto LH launchers At higher density  all RF systems can couple power to the plasma. Heat flux sources are identified from IR and calorimetry analysis in dedicated experiments Interaction Mechanism Heat load location Controller action Choc 35611-C3 LH  LH Fast e- (proportional to: PLH, ne,grill) Decrease the LH private power the launcher See A. Ekedahl PSI 2006 Launcher side protection ICRH  LH Fast ions orbit drift in rippled field (proportional to: PFCI, 1 / ne2) Decrease ICRH total power Choc 36143 (67.4s) – C3 Goniche et al. EX/P6-12 Lower part of LH-launcher

10. Analysis of RF heat flux sources onto ICRH antennas From IR camera and calorimetry analysis Interaction Mechanism Heat load location Controller action LH  ICRH Fast electrons accelerated at grill mouth (a PLH, ne,grill) Choc 35568-Q5 Decrease the total LH-power Side protection of antenna See A. Ekedahl PSI 2006 ICRHICRH RF sheath effects Decrease the ICRH private power Choc 35961-Q1 Antenna screen and septum Goniche et al. EX/P6-12 Identified over-heat flux area inserted in the controller and linked for relevant action

11. n// of LH wave HXR width Shot 36192 (BT=3.7T, n/nG=0.65) PLH , PICRH IR temperature 5 PLH [MW] 4 Ip [MA] 3 0.6 2 PFCI [MW] 0.4 1 0.2 0.6 2.2 n// 0.55 0.5 2.0 700°C 800°C Reference HX-ray width 0.45 PLH 1.8 800 100% Protection TIR [°C] 600 1.0 400 LH-power [MW] 0.5 25% 200 0 10 20 30 40 50 60 70 Time [s] TIR Integration of profile control and IR-avoidance scheme (1) IR limit avoidance algorithm: LH launcher side protection LH launcher IR view • n// increase leads to: •  PReflec increase •  TIR increase on LH launcher (fast e-) • PLH modulated by controller Profile control achieved despite PLH modulation

12. 36194 (BT=3.7T ; <ne>=2.5.1020 m-3) n// and PLH HXR width PLH , PICRH 1.0 2 IR temperature PICRH [MW] 1 0.5 Ip [MA] VLoop [V] 3 2.5 2 PLH [MW] n// 1 2 0.5 1.6 HXR profile width 0.4 1.4 qo 1.2 0.3 1 1000 1.0 PQ1 [MW] 0.5 900 TIR [Deg] 0 10 20 30 40 50 Time [s] Integration of profile control and IR-avoidance scheme (2) With « Search optimisation » algorithm Optimum found n// Target: broadest HXR profile Start • Integrated stationary scenario achieved with: • Constant Vloop • qo increases by 0.4 • No MHD detected PLH Antenna septum ICRH antenna IR view

13. Conclusions In actively cooled device with CFC components, optimising current drive deposition and producing broader q profileappears feasible using integrated control in stationary scenario for. It looks also compatible with local heat flux control of PFCs for durations exceeding ten resistive times. In Tore Supra, plasma operation with PLOSS/SSEP approaching ITER values for long duration (>60s) and high power demonstrate the importance of the heat flux analysis and controlfor stationary or steady state scenario. This work is pioneering the integration work that will be required on the operation of ITER stationary and steady state scenarios when combining several types of challenging plasma controls (global performance control, profile control, radiation control and plasma instability control) and limit avoidance schemes.