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FY2004 Research Plan

S. M. Kaye for the NSTX Research TeamPPPL, Princeton Univ.

NSTX PAC-15 MeetingPrinceton, N.J.

12-14 January 2004

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Outline

• 2004 Goals and Capabilities

• Topical area research program is organized by ETsand is driven by research milestones– HHFW/EBW Heating and Current Drive (Taylor, Ryan)– Non-Solenoidal Startup (M. Bell, Raman)– MHD (Sabbagh, Gates)– Transport and Turbulence (Maingi, Stutman)– Boundary Physics (Kugel, Kaita)– Integrated Scenario Development (Menard, Wilson)

• Research plan schedule

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Program Planning Steps

• NSTX Research Forum (9/02)• PAC-13 (9-10/02)• PAC-14 (1/03)• Curtailed FY03 run (1-2/03)• Five Year Plan (6/03)• NSTX Research Forum (11/03)• PAC-15 (1/04)

• Plan – 18 run weeks in FY04

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Run Plan Addresses Milestones By Exploring Fundamental ST Physics

• Highest level milestone (FY04-1)– Assess confinement and stability in NSTX by

characterizing high confinement regimes with edge barriers and by obtaining initial results on the avoidance or suppression of plasma pressure limiting modes in high-pressure plasmas

(T&T, MHD, ISD)

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Many Topical Areas Have Specific Milestones

• T&T (FY04-2)– Measure long-wavelength turbulence in ST plasmas in a

range of plasma conditions• HHFW/EBW, T&T (FY04-3)

– Measure plasma current profile modifications produced by RF, NBI and p techniques

• Solenoid-free startup (FY04-4)– Conduct initial tests combining available techniques to

achieve solenoid-free initiation to substantial currents• HHFW/EBW (FY04-5)

– Measure EBW emissions to assess heating and current drive requirements

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Run time allocations for FY04 Represent a Balanced Scientific Approach

# Run Days %

HHFW/EBW 12 days 13%Solenoid-free startup 11 days 12% Transport & Turbulence 11 days 12% MHD 11 days 12%ISD 11 days 12% Boundary physics 8 days 9% Enabling/cross-cutting 12 days 13%Scientific Contingency 14 days 16%

Total 90 days

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Heating and Current Drive (HHFW/EBW)

• Two FY04 milestones– Measure plasma current profile modifications produced by RF,

…– Measure EBW emissions to assess coupling requirements for

heating and current drive

• New capabilities in 2004– Feedback control of antenna loading to be implemented mid-

FY04– MSE (3 10 channels)– HHFW antenna modified to increase voltage/power limit (FY03)– CURRAY integrated into TRANSP– Increased use of CURRAY, CQL3D, AORSA1D for discharge

scenario development (also in ISD)

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HHFW FY04 Research Plan

• HHFW coupling, power deposition and heating– Establish good coupling for electron heating

• DND– Explore parametric decay mechanism

• Possible source of edge ion heating– RF modulation/USXR for PRF(r)

• HHFW Current Drive – Dependence on power, density, temperature and phasing– Measure j with MSE

• HHFW-only H-mode– SN, DN target development

• HHFW + NBI: important for Five Year objectives– High-t or high-Te (RS) NBI target

Hot Component

Cold Component

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EBW FY04 Research Plan

• FY2004 research focused on establishing basis for high power heating and current drive system

• Demonstrate 80% B-X and/or B-X-O conversion – Use limiters to reduce Ln and increase conversion

efficiency– Reflectometry to measure Ln

– Local gas feed to ensure adequate density– Modulate HHFW to suppress edge density fluctuations

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Solenoid-Free Startup• Milestone FY04-4

– Conduct initial tests combining available techniques to achieve solenoid-free initiation to substantial currents

• New capabilities in 2004– Co-axial helicity injection

• Capacitor bank for transient CHI (mid-FY04)• New ceramic insulator (FY03)• EFIT with open field line current• 3D modeling of resistive linear and non-linear stability

– PF-only startup• PF4 power supplies for “outer PF” startup (mid-FY04)• HHFW to assist plasma formation• DINA calculations (resistive MHD and transport) for scenario and control system

development

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CHI FY04 Research Plan• Employ transient CHI scenario

– Continue FY03 exp’ts but with cap bank for rapid rate of rise of injector current

– Build on development made in HIT-II– PF3L to “pinch off” plasma for closed

flux

• Add CHI to inductive discharge– Gained experience and understanding

in HIT-II experiments

• Determine need for absorber field nulling coils– Extended CHI pulse – Assess new absorber

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PF-Only Startup FY04 Research Plan

• Outer PF startup – additional discharge scenario development required (TSC, DINA)– Bipolar BV swing (no field null)

• HHFW/ECH plasma source– Outboard null

• No PF4: 100 kA• PF4: 100’s kA

– HHFW assist• Initiate plasma on outboard side• Drive 50-100 kA with PF ramping• Use HHFW to heat and drive current

further• HHFW rampup

– Clamp OH current after Ip=50-100 kA– Apply HHFW to heat and drive current

20 kA

- 20 kA

2.8 kA

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MHD Stability• MHD stability a critical part of highest level milestone

– ….obtaining initial results on the avoidance or suppression of plasma pressure limiting modes in high-pressure plasmas…

• Related research topics– Influence of shape and rotation on equilibrium and stability– Effect of error fields– RWM, ELM, NTM physics– Fast ion MHD

• New capabilities in 2004– 6 External EF/RWM control coils (developing)– Fast power supplies for EF/RWM control (summer 2004)– MSE (up to 10 channels)– USXR, FIRETIP upgrades– Control system upgrade for higher elongation– Divertor Mirnov arrays, internal RWM sensors (FY03)– EFIT with rotation, expanded data input; FLOW– MARS

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Shape and Rotation Influence Strongly Plasma Stability

• N up to 6 achieved at high elongation

• FY04 Research Plan - High-N – High-T @ high IN (high ): 2.4

with improved control system– High-p through Ip ramp down: test

effect of rotation, R/a on pressure surface shift

– Effect of boundary shape on high-n stability (need PF4)

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Shape & Rotation – FY04 Research Plan (cont’d)

Mode saturation due to shear flow possible (internal and external)

• Error fields– Effect of EF correction on plasma rotation, low-n stability*

• RWM physics– Mode structure (internal coils) – RWM dissipation, rotation damping physics– Fast feedback for active control

• NSTX/DIII-D similarity experiments (ITPA priority)– RWM characteristics, dissipation, etc.– EF amplification

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Additional MHD Studies• Fast ion MHD

– Parametric dependence of fast ion losses on Ip, BT, q0

• TAE, CAE, GAE– Suppression of frequency

“chirping” in fishbone instabilities• Non-linear mechanism• Similarity exp’t with DIII-D (chirping

observed on NSTX but not on DIII-D)• Neoclassical Tearing Mode

Onset – -scan

• ELM stability vs shaping (piggyback)

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Transport and Turbulence

• FY04-1– Assess confinement and stability in NSTX by characterizing

high confinement regimes with edge barriers and …….• FY04-2

– Measure long-wavelength turbulence in ST plasmas in a range of plasma conditions

• FY04-3– Measure plasma current profile modifications produced by …

p techniques

• Related research topics– Establish E and transport scalings– Study electron transport physics– Determine influence of Er (ExB) and T on turbulence,

transport, L-H transitions and pedestals

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Transport and Turbulence

• New capabilities in 2004– MSE– 51 channel CHERS (FY03)– Scanning NPA (FY03)– Edge Rotation Diagnostic (FY03) - Er

– Prototype neutron collimators– Upgraded correlation reflectometry – long

turbulence– Fixed frequency reflectometers (4) – long turbulence– mm-wave interferometer: line-integrated long

turbulence– Upgraded Gas Puff Imaging (GPI), reciprocating probe

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Parametric Scaling Trends Have Been Studied

• L-mode scaling presented to PAC13 (10/02) and PAC14 (1/03)

• Non-linear H-mode power dependence– Ip, BT, etc parameter ranges too

limited to perform meaningful scaling

ENSTX-L ~ Ip

0.76 BT0.27 PL

-0.76

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E and Transport Scalings – FY04 Research Plan

• Systematic H-mode and ITB studies in quasi-steady discharges– DND to connect to international

database– NSTX/MAST identity exp’ts

• ITPA high priority

• NSTX/DIII-D similarity – R/a effects at fixed pol, *

pol

• Dimensionless scalings within NSTX– OH/NBI R/a– Initial *, T (ITPA high priority)

-scalings will also be developed from the results of these XPs

2x 1x

0.5x

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• Scenarios for these studies require development of reproducible H-modes: L-H threshold studies– DN, LSN– Role of shape, fueling type, fueling location

• NSTX/MAST identity (ITPA priority)• ELM characteristics

– Pedestal characterization• NSTX/MAST/DIII-D similarity (ITPA priority)

E and Transport Scalings – FY04 Research Plan (cont’d)

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Electrons Dominate Transport Loss

Large uncertainties in ’s in center and near edge due to data/equilibrium uncertainties 51 point CHERS should help resolve some uncertainties - Better defined gradients

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• New diagnostics allow us to investigate the relationship between magnetic shear reversal and improved electron confinement– Electron ITB w/NBI, HHFW

• Relation to critical gradient physics– ’ scan

• Comparison of NBI vs HHFW transport– Vary fractions of simultaneous NBI, HHFW power

• Need to develop successful synergistic scenario– Momentum transport studies

Local Transport – FY04 Research Plan (cont’d)

GS2 Calculations

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• New and upgraded diagnostics allow for measurement of fluctuations closer to the plasma core– Initially, study L-mode plasmas (low ne NBI & RF)

• Combined edge turbulence study– GPI: higher spatial/temporal extent, resolution– Recip. probe: multiple tips to resolve Te, ne and Er, Epol, B, Te, fluctuations– w/Boundary ET

Core and Edge Turbulence – FY04 Research Plan

FIRETIP Reflectometry

Accessibility

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Boundary Physics • Enabling technology

– Develop and evaluate particle control techniques– Assess fueling and particle pumping needs– Evaluate power handling needs and solutions

• Science– Characterize edge power and particle transport regimes– Measure edge turbulence (with T&T)

• New capabilities in 2004– Low-Z pellet injector (Li/B/C)– Supersonic gas injector– Improved boronization schemes– Upgraded reciprocating probe– Edge rotation diagnostic (FY03)

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Fueling and Particle Control – FY04 Research Plan

• Supersonic gas injection to enhance fueling efficiency

• Low-Z pellet injector (Li/B/C)– 10-400 m/sec (controllable), 1 to 8 pellets/discharge– Particle control using Li wall coatings– Characterize low-Z pellet ablation, impurity transport

• Improved boronization techniques– Daily boronization– Boronization during high temperature bakeout

• More uniform deposition

Density control a key issue for long pulse discharges

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Power and Particle Control – FY04 Research Plan

• Establish heat flux scaling and power accountability– Parametric scaling (Ip, ne, Pheat)– H vs non-H, SN/DN configurations– Detailed edge characterization of edge for SOL transport studies– NSTX/MAST comparative studies

• Test methods for reducing heat flux – X-point sweeping– Detached divertor

• Investigate impurity transport– Sources/sinks of C under various conditions– Connect to edge convective

transport theory

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Integrated Scenario Development

• Highest level milestone requires integration of techniques to produce high performance plasmas– Simultaneous high-t, E for long duration (FT >> E)– NBI/HHFW compatibility

• New capabilities in 2004– Control system upgrades

• Decreased latency– HHFW loading, outer gap control– GA rtEFIT shape control (continuing)– Improved wall conditioning– Improved gas injection/density control

Control system speedup 8/19/03 (Reduction = 0.22)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00Latency (ms)

Original

Software optimized

Hardware+software optimized

Time (msec)

Dat

a B

its

Original System (~ 3 msec)

New System (< 1 msec)

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ISD 2004 Research Plan• Control system development

– Shape, vertical control (validate GA MIMO feedback algorithm, TSC models)

• Shape optimization predicted to improve performance– High- in DN, LSN ( =2 to 2.4)

• Increased stability limits, higher pulse, E

• Long pulse operation can also be aided by– Early HHFW heating to raise Te

• Reduce OH flux consumption– Triggering H-mode during Ip ramp

• Broader p(r) Higher pol higher Ip

• Possible shear reversal– HHFW-only H-mode

• Increased Ibs (fBS ~ 0.40 previously)

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ISD 2004 Research Plan (cont’d)

• HHFW/NBI compatibility desirable for attaining ultimate target objectives– Couple HHFW into high-T NBI target plasma– Couple HHFW into low-ne, high-Te (RS) NBI target

plasma– Couple NBI into HHFW-driven H-mode

• Application of density control techniques for long-pulse operation

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FY04 Research Aimed Towards Early Development of High-Performance Plasmas

Early Run Mid-Run Late RunH&CD

Startup

MHD

T&T

Bdy

ISD

HHFW conditioning - Decay B-X-O, B-X EBW HHFWCD w/j(r) measurementsHHFW Power Deposition HHFW + NBI Thermal Ion Htg, CD, HHFW Htg Efficiency/Ponderomotive Effects H-modeCHI into inductive Transient CHI Absorber null assessmentHHFW startup Solenoid-free startup with PF4

High-t at high NSTX/DIII-D RWM similarity Stability studies with j(r) meas. High-pol aspect ratio effects RWM dissipation, rotation damping Effect of boundary on high-nRWM passive stabilization Neoclassical Tearing Modes Suppression of fishbone chirpingCollective fast ion loss Active EF/RWM control

NSTX/MAST L-H Core, edge turbulence NSTX/DIII-D similarityFast ion profile PNBI vs PHHFW transport Dimensionless scaling in H-modeNSTX/MAST H-mode scaling Electron ITBs (RS) NSTX/MAST/DIII-D pedestal Intra-machine R/a scaling Momentum transport

SS Gas Injector Boronization schemesDensity control Edge turbulenceDetached divertor Boundary characterization Li particle control, Low-z pellets

Control system development Long-pulse HHFW H-mode USN w/ Reversed BT High- LSN, DN Fueling during long-pulse H-modesHHFW/NBI compatibility H-mode during Ip ramp

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Similar to the the PPPL display wall roomA productive collaboration among PU/PPPL/NSTX

A Collaborative Control Room Will Aid Run Productivity

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NSTX Has Developed a Run Plan to Address a Broad Spectrum of Scientific Issues

• Experiments support the near-term milestones of the Five Year research plan

• Experimental proposals will take advantage of significant new facility and diagnostic capability to probe the underlying physics

• Information will add to the ITPA effort and contribute to our understanding of toroidal physics

• 18 run weeks will allow us to address most of our goals

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i i, neo near core