Multi-Scale Transport and Turbulence Physics in NSTX Stanley M. Kaye For the NSTX Team Tokamak Planning Workshop PSFC, MIT Sept 17, 2007 Supported by Office of Science Culham Sci Ctr U St. Andrews York U Chubu U Fukui U Hiroshima U Hyogo U Kyoto U Kyushu U Kyushu Tokai U NIFS Niigata U U Tokyo JAERI Hebrew U Ioffe Inst RRC Kurchatov Inst TRINITI KBSI KAIST ENEA, Frascati CEA, Cadarache IPP, Jülich IPP, Garching ASCR, Czech Rep U Quebec College W&M Colorado Sch Mines Columbia U Comp-X General Atomics INEL Johns Hopkins U LANL LLNL Lodestar MIT Nova Photonics New York U Old Dominion U ORNL PPPL PSI Princeton U SNL Think Tank, Inc. UC Davis UC Irvine UCLA UCSD U Colorado U Maryland U Rochester U Washington U Wisconsin

SMK – TPW 2 NSTX Can Address T&T Issues Critical to Both Basic Toroidal Confinement and Future Devices Critical issues for future (including Burning Plasma) Devices (ST-PE, CTF; ITER) –Confinement enhancement (H-factor) at low & high P heat /P LH –Hot-ion H-mode operation - neoclassical ion transport –Maximize neutron production &/or fusion gain – optimize electron transport –Predictive understanding necessary NSTX can address these issues –Dominant electron heating with NBI: relevant to  -heating in ITER –Strong rotational shear that can influence transport –Anomalous electron transport can be isolated: ions close to neoclassical –Large range of  T spanning e-s to e-m turbulence regimes –Localized electron-scale turbulence measurable (  e ~0.1 mm)

SMK – TPW 3 Transport and Turbulence Studies Take On a Multi-Faceted Approach Transport coupled to turbulence measurements over a wide k-range Experiment coupled to gyro-kinetic theory/simulation results - GTC-NEO, GS2, GYRO, GTC, GEM - pTRANSP Verification and validation of theory and models at all levels - Synthetic diagnostics in gyro-kinetic codes - Fluctuation spectra, mode structure - Transport fluxes,  ’s, D’s Ultimate goal: Comprehensive Understanding Predictive Tool ETG ITG/TEM  TEARING KBM k  (cm -1 )  wave Scattering Low-k  wave Imaging

SMK – TPW 4 Global Confinement Research Has Established Scaling Trends wrt Dimensional and Dimensionless Variables 4 MW (Kaye et al, PRL 46 [2006] 848)  -scaling high priority ITPA topic: Shape (ELMs) matter! Parametric dependences differ from those at higher R/a  =2.1  =0.6  =1.85  =0.6

SMK – TPW 5 Global Confinement Studies are Important for Being Able to Predict the Performance of Future Devices –Source of variation in  -degradation of confinement important for ITER ELMS vs shape (are the two coupled)? –Dependence of  E on R/a for optimizing ST-PE, CTF designs Within NSTX (limited range accessible: 1.3 to 1.6) Complete NSTX/DIII-D similarity experiment –Verify scaling trends at high P heat /P LH to support ST-PE, CTF physics designs Second beam line (+ 6 MW) Most global confinement studies have given way to local transport studies, but some important research opportunities remain

SMK – TPW 6 Ion Transport Found to Be Near Neoclassical In H-modes Neoclassical levels determined from GTC-Neo: includes finite banana width effects (non-local) Controls  E scaling with I p Neoclassical Neoclassical orbit squeezing/shrinking may be responsible for setting  i -scale limit of T i gradient Linear GS2 calculations indicate suppression of low-k turbulence by ExB shear during H-phase (GTC non-linear also)

SMK – TPW 7 Goal of Ion Transport Studies is to Establish a Predictive Understanding of Transition Between Neoclassical and Turbulent Transport Regimes –Actively change ITG/TEM driving/damping terms (T e /T i, ExB shear) HHFW → NBI, Non-Axisymmetric Magnetic Perturbations (NAMP) braking –nRMP to slow plasma, reduce ExB to point where ion transport becomes anomalous –Relation of first low-k turbulence measurements to transport Low-k fluctuation diagnostic Full FIDA, neutron collimators for P heat –Role of Zonal Flows in edge Doppler reflectometry, ERD upgrade –Ion internal transport barrier studies Relation to current profile, integer q, Zonal Flows Validation of neoclassical orbit shrinking theory - Predictive understanding crucial for design/operation of ST-CTF (neoclassical ions) - NSTX tools allow for transitioning between turbulent and neoclassical transport

SMK – TPW 8 Ion Transport Research in Latter Part of Five Year Plan Will Allow Us to Draw Definitive Conclusions Concerning Neoclassical vs Turbulent Transport –More detailed comparison of inferred  i and low-k fluctuations to gyro-kinetic predictions Comprehensive validation of neoclassical and ITG theories –Synthetic diagnostics built into G-K codes Assessment of non-local transport due to large   Zonal Flow dynamics in edge and core (test theoretical q-dependence) –Assessment of ion transport and turbulence levels at high P heat /P LH at various ExB for establishing physics basis for ST-PE, CTF Second beamline Internal coils for NAMP braking –Neoclassical theory development with full FLR 2013 –Low-to-medium k turbulence levels measured with Microwave Imaging Reflectometer –Ion transport in OH, RF plasmas with T i /T e <1 Imaging X-ray crystal spectrometer (non-beam based)

SMK – TPW 9 NSTX Is In a Strong Position to Study and Understand Electron Transport Electron transport anomalous: controls B T scaling Consistent with high-k fluctuations Low-k microtearing important in “Hybrid” and weak RS discharges High-k (ETG?) fluctuations seen to increase with increasing R/L Te 14 cm -1

SMK – TPW 10 A Predictive Understanding of Electron Transport is Critical to Optimizing Fusion Gain/Neutron Production for BP Devices –ID of TEM/ITG using present high-k system Collisionality scans Establish critical gradient using HHFW to change R/L Te Connect to inferred transport levels –Full FIDA, neutron collimators for P heat (r) –Role of RS, low order rational q for eITB formation –Microtearing mode ID Change driving/damping(?) terms:    ExB shear Initial internal  B measurements with MSE –Perturbative electron transport using ELMs and pellets High resolution edge SXR Relation to high-k turbulence Compare measurements to results of gyrokinetic calcs with built in synthetic diagnostics for V & V - Electron transport is one of the top research priorities - Anomalous electron transport can be “isolated” (i.e., ion transport neoclassical)

SMK – TPW 11 Electron Transport is One of the Top Research Priorities –Local modification of electron transport and turbulence Low power EBW (200 kW) Modify q-profile to induce electron ITB Assess turbulence spreading with low and high-k fluctuation measurements –Modulated EBW to probe local critical gradient physics High-resolution Tangential Optical SXR (TOSXR) Relation to changes in high-k turbulence –Microtearing mode ID continued Internal  B, low-k for mode structure –Verify transport trends at high P heat /P LH Second beamline 2012 – 2013 –Detailed medium-to-high k turbulence with k r & k  Microwave scattering high-k  upgrade Microwave Imaging Reflectometer Mode structures, full frequency spectra, dispersion characteristics Radial streamer ID –Localized heating to probe critical gradient physics, turbulence spreading High power EBW (2 MW) Full V & V critical to effort

SMK – TPW 12 Momentum Transport Studies Will Address Source of High-Rotation and Relation to Energy Transport  i,   scaling different at low R/a Perturbed momentum transport studies using nRMP (n=3) braking and spin-up indicates significant inward pinch velocity Due to ITG suppression? Is   neoclassical? Peeters et al Fit with finite v ,pinch Fit with v ,pinch =0 TRANSP 2009 – Validation of neoclassical theory (poloidal CHERS for v  ) - Determine v pinch,   under a variety of conditions - NAMP for magnetic braking - Tests of inward pinch theories - Test of NTV theory for magnetic braking - Comparison with initial low-k Relation of v pinch,    to low-k in both L and H - Zonal flows/GAMs and relation to other microinstabilities - Further v pinch,   assessment (internal NAMP coils for magnetic braking) Intrinsic rotation studies with Imaging X-ray Crystal Spectrometer

SMK – TPW 13 Particle Transport Studies Important for Establishing Regimes of Turbulent vs Neoclassical Transport Impurity injection experiments/theoretical modeling indicate neoclassical level transport for injected Neon in H-mode - Consistent with neoclassical ion energy transport D & particle transport in core (NBI-fueling dominated) - NUBEAM for S(r) - Relation to thermal , transport, core turbulence (low-k) - Density peaking - Modulated core fueling with beam blips; determination of D pert, v pinch - D & particle transport in outer region - S(r) from extended modeling (DEGAS2/UEDGE) - Relation to edge turbulence (Boundary) - Impurity transport using gas puffing, TESPEL, high res SXR to deduce D pert, v pinch - Helium transport studies (He puffing or He discharges) 2011 – Determine role of low-k turbulence in controlling particle transport - Modulated particle transport studies continue with second beamline Effect of Lithium conditioning

SMK – TPW 14 Theory Tool Development 2D/3D state-of-art neutrals package for transport studies (TRANSP) Full FLR effects for complete non-local neoclassical transport Gyro-kinetic codes –GS2 (flux tube) –GYRO –GTC (kinetic electrons, finite- , multi-ion species) –GEM (low-k microtearing, kinetic electrons for ETG) –Synthetic diagnostics for V & V –High + Low k non-linear calculations numerically expensive: is scale- separation possible when ITG suppressed, or is turbulence spreading important? Predictive tools –pTRANSP for scenario development –Low R/a relevant transport model (TGLF?)

SMK – TPW 15 Proposed Five-Year Research Plan ( )