Overview of First Results from NSTX-Uand Analysis Highlights from NSTX
Jonathan Menard (PPPL)On behalf of the NSTX-U Research Team
26th IAEA Fusion Energy Conference
Kyoto, Japan
17–22 October 2016

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U Program is Highly Collaborative
Domestic (33)International (22)College of William and Mary
Columbia University
CompX
Florida International Univ.
General Atomics
Idaho National Laboratory
Johns Hopkins University
Lawrence Livermore Nat. Lab.
Lehigh University
Lodestar Research Corporation
Los Alamos National Laboratory
Massachusetts Institute of Tech.
Nova Photonics, Inc
Oak Ridge National Laboratory
Old Dominion University
Princeton Plasma Physics Lab
Princeton University
Purdue University
Sandia National Laboratory
Tech-X Corporation
U. of California - DavisU. of California - Irvine
U. of California - Los Angeles
U. of California - San Diego
U. of California - Space Sci. Lab.
University of Colorado
University of Illinois
University of Maryland
University of Rochester
University of Tennessee
University of Texas
University of Washington
University of Wisconsin

ASIPP
CCFE
FOM Institute DIFFER
Hiroshima University
Inst. for Nuclear Research
IPP-Czech Republic
Ioffe Physical-Tech. Inst.
JAEA
KAIST
Kyoto University
Kyushu University
NFRINIFS
Niigata University
Seoul National University
Tokamak Energy, LTD
TRINITI
UNIST
University of Costa Rica
University of Hyogo
University of Tokyo
University of York

350+ data users
55 institutions
22 US Universities
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

2Outline• NSTX-U mission• Research highlights• Progress on next-step ST concepts• Summary
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U Mission Elements:ITER• Explore unique ST parameter
regimes to advance predictive
capability - for ITER and beyond• Develop solutions for plasmamaterial interface (PMI)
Snowflake/X• Advance ST as Fusion NuclearScience Facility and Pilot Plant

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

Liquid metals / LiST-FNSF /Pilot-Plant

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NSTX-U will access new physics
with 2 major new tools:
1. New Central Magnet

2. Tangential 2nd Neutral Beam

Higher T, low ν* from low to high β
Full non-inductive current drive
 Not demonstrated in ST at high-βT
 Unique regime, study new
Essential for any future steady-state ST
transport and stability physics
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U will have major boost in performance
1. New Central Magnet

2. Tangential 2nd Neutral Beam

Performance goals:
2× toroidal field (0.5  1T)
2× plasma current (1  2MA)
5× longer pulse (1  5s)

2× heating power (5  10MW)• Tangential NBI  2× current drive efficiency

4× divertor heat flux ( ITER levels)Up to 10× higher nTτE (~MJ plasmas)

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U had scientifically productive 1st year
• Achieved H-mode on 8th day of 10 weeks of operation• Surpassed magnetic field and pulse-duration of NSTX• Matched best NSTX H-mode performance at ~1MA
• Identified and corrected dominant error fields• Commissioned all magnetic and kinetic profile diagnostics• New 2nd NBI suppresses Global Alfven Eigenmodes (GAE)• Implemented techniques for controlled plasma shut down,
disruption detection, commissioned new tools for mitigation• 2016 run ended prematurely due to fault in divertor PF coil
– Coil forensics, design (re)-reviews, preparing for new coil fabrication– Aim to resume plasma operation end of 2017 / early 2018
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U Mission Elements:• Explore unique ST parameter
regimes to advance predictive
capability - for ITER and beyond

ITER

Topical science areas:– Scenario Development– Macroscopic Stability– Transport and Turbulence– Energetic Particles

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U Mission Elements:• Explore unique ST parameter
regimes to advance predictive
capability - for ITER and beyond

ITER

Topical science areas:– Scenario Development– Macroscopic Stability– Transport and Turbulence– Energetic Particles

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U has surpassed maximum
pulse duration and magnetic field of NSTX
Compare similar NSTX / NSTX-U Boronized L-modes, PNBI=1MW

4x longer

NSTX-U L-mode duration
exceeds longest NSTX H-mode

NSTX-U BT > highest NSTX BT

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)10n=1 error field correction (EFC) optimized tomaximize pulse length, discharge performance• L-modes used to identify optimal correction amplitude, phase

EFC current [kA]

• Multiple compass scansconfirm optimal L-mode
EFC in flattop

ne = 2.9 ×1013 (solid)
ne = 1.4 ×1013 (dashed)

EFC current [kA]
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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Recovered ~1MA H-modes with weak/no core MHD(comparable to best NSTX plasmas at similar plasma current)
202946 – no EFC 204112 – EFC v2
203679 – EFC v1 204118 – EFC v2

H98 ≥ 1, βN ~ 3.5-4 ≥ n=1 no-wall limit

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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Accessed low li and high κ using progressively
earlier H-mode and heating + optimized EFC
Future goal
H-mode flattop

NSTX-U (5 run weeks)
NSTX (10 years)

L-mode flattop• NSTX-U: Additional sensors improve estimation of Z, dZ/dt• Goals for next run:– Access li = 0.5-0.7, κ=2.4-2.7, BT = 0.75-1T, IP = 1.5-2MA
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

13NSTX-U Mission Elements:• Explore unique ST parameter
regimes to advance predictive
capability - for ITER and beyond

ITER

Topical science areas:– Scenario Development– Macroscopic Stability– Transport and Turbulence– Energetic Particles

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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Disruption characterization and forecasting capability
initiated for NSTX-U as part of disruption avoidance planγτw contours vs. ν and ωφ

Normalized growth rate vs. time

Increasing
time

idealstable

Ideal + kinetic• ex: verticaldisplacement,pressure peaking,tearing modes…

• Predict events in
disruption chains• Cues disruption
avoidance system

unstabledisruption• Identify disruption
event chains andelements

Example: Reduced kinetic resistive wall mode (RWM)
model developed for calculating growth rate vs. timeγτw

New DECAF(Disruption EventCharacterizationAnd Forecasting)code written

139514• Initial tests on NSTX RWM database

predicted instability– 86% of RWM shots are predicted unstable• Possible to predict growth rate in real time
J.W. Berkery et al., Poster EX/P4-34, Wednesday afternoon
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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Implemented automated ramp-down for NSTX-UIP• Plasma control system
detects loss of control– Central solenoid coil near
maximum allowed current– Vertical oscillations exceedthreshold– ABS(Ip–Ip request ) above threshold

IP Request(including asynchronoustransition to rampdown)

ZP(dZP/dt) threshold
ZP(dZP/dt)“State”

Fast IP Rampdown
Normal• “State-machine” based:– Feedback control switches tonew “states” that attempt tostably ramp-down the plasma

Insufficient IP

Typical ZP w/o fast ramp-down

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

ZP from EFIT16

Leading studies of rotating halo currents through
ITPA multi-machine analysis and M3D-C1 simulations
ITPA multi-machine analysis (MDC WG-6):• Halo current data from C-Mod, DIII-D, AUG, NSTX
• All measurements in lower divertor (> 400 shots)• Halo current rotation predominantly counter-Ip (not shown)• Consistent rotation velocity, vh ~ 5 km/sec

M3D-C1 simulations:• NSTX(-U) geometry• Simulate in 2D while q >2
• Switch to 3D to resolve
halo rotation (in progress)• D. Pfefferlé et al. (PPPL)

C.E. Myers et al., Poster EX/P6-46, Thursday afternoon
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U Mission Elements:• Explore unique ST parameter
regimes to advance predictivecapability - for ITER and beyond

ITER

Topical science areas:– Scenario Development– Macroscopic Stability– Transport and Turbulence– Energetic Particles

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX: Using global non-linear GTS gyrokinetic
code to study low-k ion and electron transport
GTS global capability important for treating larger ρ*~0.01 of NSTXNSTX NBI H-mode 141767, t=332ms, BT =5.5 kG• Low-k turbulence for r/a~0.7-0.85– Turbulence later suppressed by ExB shear• Total ion energy flux Qe from GTS
generally agrees with experiment
Y. Ren et al., Poster P4-35, Wednesday afternoon• Electron energy flux Qe from GTS
only significant for r/a~0.7-0.85• But GTS Qe << experimental Qe– Electron Temperature Gradient (ETG) or
electromagnetic (EM) effects important?

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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GYRO simulations of high-k Electron Temperature
Gradient (ETG) turbulence find ∇ne stabilizing
High-kµ-wave
scattering

NSTX: Decrease in ETG turbulence amplitude w/ increasing ∇neScattering
regionETG
NSTX 141767∇Te ~ constantExperiment ~(δne/ne)2

Simulated electron heat flux Qe [MW]Low ∇neHigh ∇neLow ∇neHigh ∇ne(Juan Ruiz Ruiz)

Non-linear
GYRO Qe

GYRO Qe << experimental Qe  Need EM, Alfvénic, low-k + high-k effects?
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U Mission Elements:• Explore unique ST parameter
regimes to advance predictivecapability - for ITER and beyond

ITER

Topical science areas:– Scenario Development– Macroscopic Stability– Transport and Turbulence– Energetic Particles

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U: Most tangential NBI generates counterpropagating Toroidal Alfvén Eigenmodes (TAEs)• Counter-propagating
TAE predicted forhollow fast-ion profiles• TRANSP: As current builds up
beam fast-ion beta profile
predicted to become hollow• 1st evidence of off-axis NBI deposition
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U tangential 2nd neutral beam suppresses Global
Alfven Eigenmode (GAE) – consistent with simulation
HYM code simulation of #204707, n=10|δBn |2t=0.44s

t=0.47st ωci• HYM code: growth of n=10 counter-GAE from 1st NBI• HYM: suppression of n=10 counter-GAE by 2nd NBI• Most unstable n-number, mode ω consistent with HYM

New 2nd NBI already powerful tool for fast ion, AE physics
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U Mission Elements:ITER• Explore unique ST parameter
regimes to advance predictive
capability - for ITER and beyond• Develop solutions for plasmamaterial interface (PMI)
Snowflake/X• Advance ST as Fusion Nuclear
Science Facility and Pilot Plant

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

Liquid metals / Li
ST-FNSF /Pilot-Plant

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Improving understanding of SOL heat flux
width trends in NSTX using XGC1 simulations• Experiment shows contraction of SOL heat flux width at
midplane with Ip as well as influence of Li conditioning
XGC1 w/ collisions  similar trends
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XGC-1: Full-f, global PIC, kinetic ionsand electrons

15• How will NSTX-U λq scale?

λq (mm)XGC1• NSTX data and XGC-1: λq ~ 1 / IP1.5

Li dose0 mg
150 mg
300 mgNSTXExperiment

B P scanUsing 139047 at665ms, 50 mg Li

10• Will SOL turbulence become important?

5C.S. Chang et al., Talk TH/2-1, Wednesday morning

00.4

0.6

0.8

11.2

1.4

IP (MA)
Heat flux width determined primarily
by neoclassical processes
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U: First systematic simulations of advanced
divertors combined with 3D fields with EMC3-EIRENE
Standard Divertor

Near-Exact Snowflake Snowflake Minus / X-divertor• Divertor heat-flux trends:

Related snowflake results from DIII-D and NSTX:
Poster EX/P3-30 - V. Soukhanovskii, Wednesday– Peaked heat loads in Near Exact Snowflake– Lowest heat loads found for X-divertor-like configurations– RMP fields do not significantly impact toroidal average heat-flux
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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Material Analysis & Particle Probe (MAPP) providing
new measurements of surface evolution in NSTX-U• Tracked C/B/O evolution, correlated with plasma performance• Implemented remote-control + between-shot analysis• Future: Use to understand complex Li chemistry and evolution
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U Mission Elements:ITER• Explore unique ST parameter
regimes to advance predictive
capability - for ITER and beyond• Develop solutions for plasmamaterial interface (PMI)

Liquid metals / Lithium Snowflake/X• Advance ST as Fusion Nuclear
Science Facility and Pilot PlantNSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

ST-FNSF /Pilot-Plant

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Recent design studies show ST potentially attractive asFusion Nuclear Science Facility (FNSF) and Pilot Plant
FNSF: Provide neutron fluence for material/component R&D (+ T self-sufficiency?)
Pilot Plant: Electrical self-sufficiency: Qeng = Pelec / Pconsumed ≥ 1 (+ FNSF mission?)
Designs integrate ST higher κ, βN + advanced divertors + HTS TF for Pilot Plant

FNSF with copper TF coils

A=1.7, R0 = 1.7m, κx = 2.7, BT=3TFluence = 6MWy/m2, TBR ~ 1

FNSF / Pilot Plant with HTS TF coils
A=2, R0 = 3m, κx = 2.5, BT = 4T
6MWy/m2, TBR ~ 1, Qeng ~ 1

FIP/P7-1 - T. Brown, Friday morning
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

J.E. Menard, et al., Nucl. Fusion 56 (2016) 106023
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NSTX-U strongly supporting advanced predictive
capability, ITER, PMI solutions, and next-step STs• Productive first year of operations on NSTX-U– Rapid H-mode access, scenario development, error field correction– Surpassed NSTX maximum magnetic field and pulse-duration– New fast-ion physics with 2nd NBI – GAE stabilization, counter TAE– Commissioned new advanced PMI diagnostics – MAPP

• Advancing predictive capability for core, edge, PMI– Developing reduced models for RWM, understanding of halo rotation– Global ion-scale turbulence (GTS), ∇n ETG stabilization– GAE stabilization from 2nd NBI consistent with simulation (HYM)– Exploring SOL widths, advanced divertor interactions with 3D fields• Developed attractive ST-FNSF / Pilot Plant concepts• Aim to resume NSTX-U physics operation in ~1+ years
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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IAEA-FEC presentations from NSTX-U• Tuesday, October 18– OV/5-2 - J. Menard, “Overview of First Results from NSTX-U and Analysis Highlights from NSTX”– TH/P1-2 - F. Ebrahimi, “Physics of Flux Closure during Plasmoid-Mediated Reconnection in Coaxial Helicity Injection”– TH/P1-6 - J.-K. Park, “Self-Consistent Optimization of Neoclassical Toroidal Torque with Anisotropic Perturbed Equilibrium in Tokamaks”– TH/P1-7 - S. C. Jardin, “Nonlinear 3D M3D-C1 Simulations of Tokamak Plasmas Crossing a MHD Linear Stability Boundary”– TH/P1-10 - A. Fil, “Modelling and Simulation of Pedestal Control Techniques for NSTX-U”– TH/P1-21 - Z. R.Wang, “Nyquist Analysis of Kinetic Effects on the Plasma Response in NSTX and DIII-D Experiments”• Wednesday, October 19– FIP/2-5 - M. Ono. “Liquid Lithium Loop System to Solve Challenging Technology Issues for Fusion Power Plant”– EX/P3-30 - V. Soukhanovskii, “Snowflake Divertor Configuration Effects on Pedestal Stability and Edge Localized Modes in NSTX and DIII-D”– TH/P3-14 - W. Guttenfelder, “Analysis and Prediction of Momentum Transport in Spherical Tokamaks”– EX/P4-30- J.-W. Ahn “Shielding and Amplification of Nonaxisymmetric Divertor Heat Flux by Plasma Response to Applied 3D Fields in NSTX and KSTAR”– EX/P4-33 - S. A. Sabbagh, “Isolation of Neoclassical Toroidal Viscosity Profile under Varied Plasma and 3D Field Conditions in Low and Medium Aspect Ratio Tokamaks”– EX/P4-34 - J.W. Berkery, “Characterization and Forecasting of Unstable Resistive Wall Modes in NSTX and NSTX-U”– EX/P4-35 - Y. Ren, “Exploring the Regime of Validity of Global Gyrokinetic Simulations with Spherical Tokamak Plasmas”– EX/P4-36 - F. Scotti, “Kinetic Profiles and Impurity Transport Response to 3D-Field Triggered ELMs in NSTX”– EX/P4-38 - R. Maingi. “Comparison of Helium Glow and Lithium Evaporation Wall Conditioning Techniques in Achieving High Performance H-Mode Discharges in NSTX”– EX/P4-40 - D. Smith, “Identification of Characteristic ELM Evolution Patterns with Alfvén-Scale Measurements and Unsupervised Machine Learning Analysis”– EX/P4-41 - E. Fredrickson, “Parametric Dependence of EPMs in NSTX”– EX/P4-42 - R. Perkins, “….A Proposed Mechanism for the Anomalous Loss of RF Power to the SOL of NSTX”– EX/P4-43 - M. D. Boyer, “Feedback Control Design for Noninductively Sustained Scenarios in NSTX-U Using TRANSP”– TH/P4-16 - G. Fu, “Hybrid Simulations of Beam-Driven Fishbone and TAEs in NSTX”– TH/P4-17 - E. Belova, “Coupling of Neutral-Beam-Driven Compressional Alfvén Eigenmodes to Kinetic Alfvén Waves in NSTX and Energy Channelling”• Thursday, October 20– EX/5-3 - A. Diallo, “Energy Exchange Dynamics across L-H Transitions in NSTX”– MPT/P5-30 - M. A. Jaworski, “High-Temperature, Liquid Metal Plasma-Facing Component Research and Development for the NSTX-U”– EX/P6-46 - C. Myers, “A Multimachine Analysis of Non-axisymmetric and Rotating Halo Currents”– TH/P6-12 - J. Lore, “Pedestal-to-Wall 3D Fluid Transport Simulations on DIII-D and NSTX”• Friday, October 21– FIP/P7-1 - T. Brown, “Development of a 3 m HTS FNSF Device and the Qualifying Design and Engineering R&D Needed to Meet the Low AR Design Point”– FIP/P7-36 - R. Lunsford, “ELM Pacing with High Frequency Multispecies Impurity Granule Injection in NSTX-U H-Mode Discharges”– FIP/P7-42 - R. Raman, “NSTX-U Contributions to Disruption Mitigation Studies in Support of ITER”
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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Backup

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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PF1AU coil developed turn-to-turn short(s)

TFOH
PF1CU
PF1BU

PF1AU

PF2U

PF3UNSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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Evolution of induced current in PF1AU• Coil carries current when
open circuited (open circuited
every shot before plasma isproduced)

MayJune turn-to-turn short• PF1AU first starts to conduct
current at the end of theMarch / April run period• Very fast degradation on the
final run day in June
• PF1AL shows no anomalies, but will pre-emptively be replaced
NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)

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NSTX-U plans for initiating conversion to high-ZPFCs and studying flowing liquid metal PFCs
1. Base high-Z tiles without Lireservoir will be tested first– Full toroidal row on OB divertor– Utilizes wire-EDM fabrication toobtain complex geometry

2. Later test pre-filled Li tiles:– Similar to capillary porous system(CPS) but applicable as divertor PFC– Passive surface replenishment– Bakeout  erodible high-Z layer/film– Test when technically ready

NSTX/NSTX-U Overview – IAEA-FEC 2016 (Menard)35