DIII D Research in Support of ITER

Transcription

1 Research in Support of ITER by E.J. Strait and the Team Presented at 22nd IAEA Fusion Energy Conference Geneva, Switzerland October 13-18, 28

2 DIII-D Research Has Made Significant Contributions in the Design and Physics Basis for ITER DIII-D Baseline Design - ELM Control - Vertical Stability - PF coil Capabilities Physics Basis - L-H Transition - Pedestal Height - Core Transport - Plasma Rotation - Fast Ions DIII-D ITER Scaled Scenario Development - Reference Scenarios - ITER-relevant Startup - High β Scenarios Control Solutions Real Time Control (Actuator) NTM Stabilization (ECCD) ELM Control (I-coil) NBI Plasma :β Rotation Control (P aux ) (P co, P ctr ) RWM Stabilization ( C-coil, I-coil) - MHD Stability - Disruption Mitigation - Particle Control Current Profile (ECCD, ECH, NBI )

3 Recent DIII-D Experiments Have Established Physics Criteria for Several Key ITER Design Choices DIII-D Baseline Design - ELM Control - Vertical Stability - PF coil Capabilities Physics Basis - L-H Transition - Pedestal Height - Core Transport - Plasma Rotation - Fast Ions DIII-D ITER Scaled Scenario Development - Reference Scenarios - ITER-relevant Startup - High β Scenarios Control Solutions Real Time Control (Actuator) NTM Stabilization ( ECC CD) ELM Control (I-coil) NBI Plasma β:β:β:β: Rotation Control (P aux ) (P co, P ctr ) RWM Stabilization ( C-coil, I-coil) - MHD Stability - Disruption Mitigation - Particle Control Current Profile (ECCD, ECH, NBI )

4 ELM Suppression Experiments Show Important Role of Resonant Magnetic Spectrum upper I-coil (inside vessel) , t=3. s 3. q 2.5 lower I-coil (inside vessel) Width of island overlap region determines stochastic character of edge q 95 operating window increases as width of stochastic layer increases q 95 q 95 D α n=1 n=2 magnetic island width Island overlap region n= Normalized Poloidal Flux I-coil and C-coil on Time (ms) 35 4

5 ELM Suppression Experiments Show Important Role of Resonant Magnetic Spectrum upper I-coil (inside vessel) , t=3.8 s Chirikov > 1 width = q 2.5 lower I-coil (inside vessel) Width of island overlap region determines stochastic character of edge q 95 operating window increases as width of stochastic layer increases q 95 q 95 D α n=1 n=2 magnetic island width Island overlap region n= Normalized Poloidal Flux I-coil and C-coil on Time (ms)

6 ITER Coil Design Guided by Experiments Maximum ELM size is correlated with width of island overlap region I-coil off I-coil on (increasing current->).8.6 large Type-I ELMs ELM mitigation range ELM suppression range ELM control coils (schematic) T. Evans, EX/4-1 V. Izzo, TH/P4-19 M. Jakubowski, EX/P6-2

7 ITER Coil Design Guided by Experiments Maximum ELM size is correlated with width of island overlap region DIII-D results support the choice of internal, multi-row coils Single I-coil row requires larger current No suppression with external, large aperture C-coils ELM control coils (schematic) T. Evans, EX/4-1 V. Izzo, TH/P4-19 M. Jakubowski, EX/P6-2

8 Control of ELM Frequency Achieved Using Oscillating n=3 Non-Resonant Magnetic Fields ELM frequency locked to twice frequency of I-coil modulation Energy loss from ELM scales inversely with driving frequency Minimum field perturbation required for pacing not yet determined

9 Experiments Have Helped to Quantify ITER s Capability for Vertical Control Performance Experiments validate theoretical calculations of control capability Maximum controllable displacement is ~2x larger using inner + outer coils (like ITER VS1 + VS2) Maximum Controllable Displacement 8 Inner + Outer Coils ITER Z (cm) 6 4 Model DIII-D 2 Uncontrollable Controllable 5 Growth Rate γ Z (rad/s) Stability limits motivate addition of internal vertical stability coils in ITER D. Humphreys, IT/2-4Rb G. Jackson, IT/P7-2

10 Experiments Have Helped to Quantify ITER s Capability for Vertical Control Performance Experiments validate theoretical calculations of control capability Maximum controllable displacement is ~2x larger using inner + outer coils (like ITER VS1 + VS2) Maximum Controllable Displacement 8 Inner + Outer Coils ITER Z (cm) 6 4 Model DIII-D 2 Outer Coils Only Uncontrollable Controllable Growth Rate γ Z (rad/s) Stability limits motivate addition of internal vertical stability coils in ITER D. Humphreys, IT/2-4Rb G. Jackson, IT/P7-2

11 DIII-D has Validated Performance Capabilities of ITER Startup and Operational Scenarios DIII-D Baseline Design - ELM Control - Vertical Stability - PF coil Capabilities Physics Basis - L-H Transition - Pedestal Height - Core Transport - Plasma Rotation - Fast Ions DIII-D ITER Scaled Scenario Development - Reference Scenarios - ITER-relevant Startup - High β Scenarios Control Solutions Real Time Control (Actuator) NTM Stabilization ( ECC CD) ELM Control (I-coil) NBI Plasma β:β:β:β: Rotation Control (P aux ) (P co, P ctr ) RWM Stabilization ( C-coil, I-coil) - MHD Stability - Disruption Mitigation - Particle Control Current Profile (ECCD, ECH, NBI )

12 DIII-D Experiments Have Achieved Fusion Performance at the Level Required for ITER Goals Flattop performance in ITER Operating Scenarios at ITER shape, aspect ratio, I/aB Reference operating case Q=1 at 15 MA, β N ~1.8, q 95 ~3.8.4 Baseline ITER Design Range li (3) Q=1 in ITER G q 95 = Time (ms) G = β N H 89 2 q 95.5 ITER Scaled E. Doyle, EX/1-3

13 DIII-D Experiments Have Achieved Fusion Performance at the Level Required for ITER Goals Flattop performance in ITER Operating Scenarios at ITER shape, aspect ratio, I/aB Reference operating case Q=1 at 15 MA, β N ~1.8, q 95 ~3 High fusion gain Q=3 at 15 MA, β N ~2.8, q 95 ~ li (3) li (3) G Baseline Q=1 in ITER G Advanced Inductive Q=1 in ITER ITER Design Range ITER Design Range q 95 = 3.1 q 95 = Time (ms) G = β N H 89 2 q 95 Low i (3) changes in PF system.5 ITER Scaled E. Doyle, EX/1-3

14 DIII-D Experiments Have Achieved Fusion Performance at the Level Required for ITER Goals Flattop performance in ITER Operating Scenarios at ITER shape, aspect ratio, I/aB Reference operating case Q=1 at 15 MA, β N ~1.8, q 95 ~3 High fusion gain Q=3 at 15 MA, β N ~2.8, q 95 ~3 Long pulse, high fluence Q=5 at 12 MA, β N ~2.5, q 95 ~ li (3) li (3) G G Baseline Q=1 in ITER G Advanced Inductive Q=1 in ITER Hybrid Q=1 in ITER ITER Design Range ITER Design Range q 95 = 3.1 q 95 = 3.3 q 95 = Time (ms) G = β N H 89 2 q 95 Low i (3) changes in PF system ITER Scaled E. Doyle, EX/1-3

15 DIII-D Experiments Have Achieved Fusion Performance at the Level Required for ITER Goals Flattop performance in ITER Operating Scenarios at ITER shape, aspect ratio, I/aB Reference operating case Q=1 at 15 MA, β N ~1.8, q 95 ~3 High fusion gain Q=3 at 15 MA, β N ~2.8, q 95 ~3 Long pulse, high fluence Q=5 at 12 MA, β N ~2.5, q 95 ~4 Fully non-inductive Q=5 at 9 MA, β N ~3, q 95 ~ li (3) li (3) G G G Baseline Q=1 in ITER G Advanced Inductive Q=1 in ITER Hybrid Q=1 in ITER Steady-State ITER Design Range ITER Design Range Q=5 in ITER q 95 = 3.1 q 95 = 3.3 q 95 = 4.1 q 95 = Time (ms) G = β N H 89 2 q 95 Low i (3) changes in PF system ITER Scaled E. Doyle, EX/1-3

16 Hybrid Scenario With Excellent Performance Accessed With Large Bore ITER Startup Large Bore startup includes Initiation on outer limiter Large cross-section early in limiter phase Early x-point formation No auxiliary heating until close to full current Excellent plasma performance β N = 2.9 H 98y2 = 1.6 G =.42 sufficient for Q = 1 in ITER at 11.6 MA q 95 G ITER Q=1 Div. D α (a.u.) P NB (MW) β N H 98y At higher q 95, hybrid scenario achieved with ~5% bootstrap current and ~1% non-inductive current G. Jackson IT/P7-2 C. Petty EX/1-4Rb

17 Shape Optimization Leads to Higher β and Higher Bootstrap Fraction Increased β with shaped plasmas due to better stability and higher current at fixed q 95 β N Pedestal and core stability improved leading to higher bootstrap fraction (up to 7%) βn 2 V SURF (V) I p =.9 MA Goal = V H Time (ms) J. Ferron EX/P4-27

18 Further Optimization with q Profile Points Toward Steady-state Power Plant Goals of β N = 5 and f BS > β N No-wall limit Experiment Ideal-wall limit l i Ballooning Limit H 98y Time (s) Strong magnetic shear (q min ~1) contributes to higher stability and good confinement Calculated bootstrap fraction is ~9% with q min ~1 Time (s) Access to β N > 3 might be possible in ITER with this scenario without wall stabilization Calculated current fractions Total noninductive Bootstrap Neutral beam ECCD J. Ferron EX/P4-27

19 DIII-D has Developed Control Solutions for Key Physics Issues DIII-D Baseline Design - ELM Control - Vertical Stability - PF coil Capabilities Physics Basis - L-H Transition - Pedestal Height - Core Transport - Plasma Rotation - Fast Ions DIII-D ITER Scaled Scenario Development - Reference Scenarios - ITER-relevant Startup - High β Scenarios Control Solutions Real Time Control (Actuator) NTM Stabilization (ECCD) ELM Control (I-coil) NBI Plasma :β Rotation Control (P aux ) (P co, P ctr ) RWM Stabilization ( C-coil, I-coil) - MHD Stability - Disruption Mitigation - Particle Control Current Profile (ECCD, ECH, NBI )

20 R (m) Resonant Amplification Increases the Sensitivity to Error Fields at High Beta q=2 2.5 Increasing error field T e (Gauss) Magnetic island forms Time (ms) Plasma response Externally applied field β N ~ no-wall stability limit 2.4 n=1 error field is ramped up with time At a critical amplitude, the plasma rotation locks, then an island grows Critical amplitude of applied field decreases with β Critical amplitude of plasma response is independent of β Strong response by stable kink mode as β increases Critical amplitude increases with NBI torque Plasma response must be considered in projections of error field correction H. Reimerdes, EX/5-3Ra J.K. Park, EX/5-3Rb

21 Active Stability Control Enables High Beta at Low Rotation Stable operation achieved by Neoclassical tearing mode (NTM) stabilization by ECCD at q=2 Feedback - controlled error field correction Non-rotating instabilities at low NBI torque appear to be NTMs RWM stability at low Ω is consistent with theoretical predictions of kinetic stabilization Ideal-wall β limit no feedback rotating mode non-rotating Toroidal Rotation (krad/s) (26) Cβ 26 IAEA (no ECCD no feedback) q=2 No-wall β limit plasma rotation at q~2 (km/s) (28) Rotation is below values anticipated in ITER M. Okabayashi, EX/P9-5

22 Active Stability Control Enables High Beta at Low Rotation Stable operation achieved by Neoclassical tearing mode (NTM) stabilization by ECCD at q=2 Feedback - controlled error field correction Non-rotating instabilities at low NBI torque appear to be NTMs RWM stability at low Ω is consistent with theoretical predictions of kinetic stabilization Ideal-wall β limit no feedback rotating mode non-rotating Toroidal Rotation (krad/s) (26) Cβ 26 IAEA (no ECCD no feedback) q=2 No-wall β limit time plasma rotation at q~2 (km/s) (28) Rotation is below values anticipated in ITER M. Okabayashi, EX/P9-5

23 Nassim (1 22 particles) Disruption Mitigation Requires Rapid Delivery of Low-Z Species Greatest remaining challenge is to achieve the Rosenbluth density for suppression of runaway electron avalanche: n e > ~ 1 22 m 3 ~ Several grams in DIII-D ~ 1 g in ITER Gas injection studies show good Studies of alternate assimilation of gas that arrives during delivery systems thermal quench have started ICF favors low-z species Ar or B -filled capsule 11 capsules H2 D2 He Ne Ar 1% assimilation short gas pulse Particles delivered in TQ (1 22 particles) Line brightness (a.u.) Spectroscopy confirms delivery of payload J. Wesley, EX/7-3Rb

24 Particle Drifts Play a Critical Role in Predictions of Radiative Divertor Performance Ion B drift : Recycling and argon dominant in outer divertor Ar controlled by pumping Z (m) D : Experiment D : UEDGE Modeling Ion B drift Argon injected into divertor follows D α pattern Ion B drift : Inner leg detaches Ar leaks into the core plasma Z (m) Major Radius (m) Major Radius (m) Ion B drift M. Groth, EX/P4-21T T. Petrie, EX/P4-21

25 Particle Drifts Play a Critical Role in Predictions of Radiative Divertor Performance Ion B drift : Recycling and argon dominant in outer divertor Drifts push ions to outer divertor Z (m) D : Experiment ExB Drifts : UEDGE Modeling Ion B drift Argon injected into divertor follows D α pattern Ion B drift : Inner leg detaches Drifts push ions to cold inner divertor Z (m) Major Radius (m) Major Radius (m) Results suggest that drifts may play a key role in particle exhaust on ITER Ion B drift T. Petrie, EX/P4-21

26 DIII-D Research has Improved the Physics Basis of Projection of ITER Performance DIII-D Baseline Design - ELM Control - Vertical Stability - PF coil Capabilities Physics Basis - L-H Transition - Pedestal Height - Core Transport - Plasma Rotation - Fast Ions DIII-D ITER Scaled Scenario Development - Reference Scenarios - ITER-relevant Startup - High β Scenarios Control Solutions Real Time Control (Actuator) NTM Stabilization ( ECC CD) ELM Control (I-coil) NBI Plasma β:β:β:β: Rotation Control (P aux ) (P co, P ctr ) RWM Stabilization ( C-coil, I-coil) - MHD Stability - Disruption Mitigation - Particle Control Current Profile (ECCD, ECH, NBI )

27 Multiple Sources of Torque Will Affect ITER s Rotation Static non-resonant n=3 fields apply a torque to the plasma rotation accelerates for cases with small, negative rotation Torque is consistent with prediction of Neoclassical Toroidal Viscosity theory drags rotation toward a non-zero offset rotation ~ ω i * Torque from non-resonant part of ELM control field predicted to be >> T NBI in ITER Other experiments show intrinsic torque consistent with thermal ion orbit loss V φ (km/s) n=3 I-coil (ka) Toroidal Velocity at rho~.8 (km/s) Co-I p Rotation Counter-I p Rotation Braking Acceleration Offset rotation Braking Time (ms) W. Solomon, EX/3-4 J. degrassie, EX/P5-2

28 New Predictive Model for Pedestal Height Agrees Well with Measurements Hydrogen plasma experiments comfirm Δ ped is insensitive to ρ* i favorable result for ITER Measured Pedestal Height (kpa) Pedestal scaling expt ITER demo, baseline scenario ITER demo, higher q EPED1 Predicted Pedestal Height (kpa) kpa Edge Pressure Profile Hydrogen Deuterium P tot Initial prediction for ITER: T ped ~4.6 kev (favorable for Q=1) N P. Snyder, IT/P6-14 R. Groebner, EX/P3-5

29 Quiescent H-mode (ELM-free) Achieved with Co-injection ELM-free operation for ~1 s radiated power, core density and pedestal density are constant QH-mode cases have strong rotational shear at the edge consistent with predicted stability of peeling - ballooning mode co QH (4 Nm) 1 STD. ELM-FREE ( Nm) 1.7 Counter QH (-4 Nm) Possible approach to ELM-free operation in ITER? K. Burrell, EX/8-4 P. Snyder, IT/P6-14

30 Detailed Diagnostic Measurements Test Gyrokinetic Transport Calculations BES δne 1-9 n2/khz 4 δne cross power Good agreement of measured and predicted heat flux Synthetic BES crosspower Expt. BES crosspower 2 r/a =.5 Qi (MW) Experimental.93 ± Frequency (khz) 5 GYRO 1.1 ±.17 Qe (MW).74 ±.2.97 ±.14 Key step in validation of GYRO code for ITER predictive capability NATIONAL FUSION FACILI TY C. Holland,TH/8-1 L. Schmitz, EX/P5-35

31 Experiments Validate the Physics of Off-axis Neutral Beam Current Drive Experiments confirm prediction that off-axis NBCD efficiency depends on magnetic field aligmnent Unfavorable alignment reduces current drive by ~4% Proposed geometry for off-axis NBCD in ITER is unfavorable (~ 2% reduction) B T +B T 4 NBI (Favorable) (Favorable) J NBCD (A/cm 2 ) Up/ + Bt NUBEAM Calculations Down/ Bt M. Murakami, TH/P3-1

32 Experiments Validate the Physics of Off-axis Neutral Beam Current Drive Experiments confirm prediction that off-axis NBCD efficiency depends on magnetic field aligmnent Unfavorable alignment reduces current drive by ~4% Proposed geometry for off-axis NBCD in ITER is unfavorable (~ 2% reduction) B T +B T 4 NBI (Favorable) (Favorable) (Unfavorable) J NBCD (A/cm 2 ) Up/ + Bt NUBEAM Calculations Down/ Bt Down/ + Bt M. Murakami, TH/P3-1

33 Experiments Validate the Physics of Off-axis Neutral Beam Current Drive Planned modification of a DIII-D beam line will provide up to 2 ka of off-axis current drive M. Murakami, TH/P3-1

34 DIII-D Research Has Made Significant Contributions in the Design and Physics Basis of ITER Physics criteria established for several key ITER design choices ELM suppression Vertical stability margin Operational envelope for H-mode operation PF coil capabilities Validated performance capabilities of ITER startup and operational scenarios Q = 1 (inductive) and Q = 5 (steady state) equivalent operation demonstrated Developed control solutions for key physics issues High β operation at near zero rotation Massive gas delivery systems for disruption control Effect of SOL drifts on particle control Improved the physics basis for projection of ITER performance L-H transition Offset rotation Turbulence code validation Fast Ion Transport Pedestal height QTYUIOP

35 Papers at This Conference Tue EX/1-3 E Doyle ITER Scenarios FT/P2-23 R Callis High Speed DT Pellets EX/1-4Rb C Petty Hybrid Scenario TH/P3-1 M Murakami Off-Axis NB Current Drive EX/P3-5 R Groebner Pedestal Height Model Wed EX/3-4 W Solomon Plasma Rotation EX/P4-27 J Ferron Steady-State Discharges EX/4-1 T Evans ELM Suppression EX/P5-2 J Degrassie Intrinsic Rotation EX/P4-19 M Groth Scrape-Off Layer Flows EX/P5-35 L Schmitz Core Fluctuations EX/P4-21 T Petrie Radiating Divertor TH/P4-19 V Izzo RMP Rotational Screening Thu EX/5-3Ra H Reimerdes Error Field Tolerance IT/P6-19 L Baylor Pellet Technology IT/P6-14 P Snyder Pedestal Stability IT/P6-8 R. Buttery NTM Physics EX/6-2 M Van Zeeland Alfvenic Instabilities IT/P6-9 R La Haye NTM Stabilization in ITER EX/P6-24 R Pinsker Fast Wave Absorption IT/P7-2 G Jackson ITER Startup Scenario Fri EX/7-3Rb J Wesley Disruption Mitigation EX/P9-5 M Okabayashi Resistive Wall Mode EX/8-4 K Burrell Quiescent H-Mode IT/2-4Rb D Humphreys Vertical Stability for ITER EX/9-3 D Rudakov Dust in DIII-D and TEXTOR TH/P8-42 G Staebler Gyro-Landau Fluid Model Sat EX/1-1 G Mckee L-H Power Threshold TH/8-1 C Holland Gyrokinetic Transport