NSTX ET1 intro

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ReNeW Theme 5 ST Panel Breakout Session
S.A. Sabbagh1, N. Gorelenkov2, C.C. Hegna3, M.
Kotschenreuther4, D. Majeski2, J.E. Menard2,
Y.-K. M. Peng5, A.C. Sontag5, V. Soukhanovskii6,
D. Stutman7 1Department of Applied Physics and
Applied Mathematics, Columbia University 2Princeto
n Plasma Physics Laboratory 3University of
Wisconsin, Madison 4University of Texas,
Austin 5Oak Ridge National Laboratory 5Lawrence
Livermore National Laboratory 5Johns Hopkins
University ReNeW Theme 5 Optimizing the
Magnetic Configuration Workshop Wednesday,
March 18th, 2009 Princeton Plasma Physics
Laboratory
V1.4
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ST Panel breakout session (Wed 1-530 PM) - Agenda

• Brief summaries of present 12 Research Needs
  areas (from draft document ST section)
• Discussion of Research Needs
• Completeness (have we left anything out?)
• Priority (is present tier ranking adequate?)
• Consolidation (should we merge / split areas?)
• Synergy (explicit connections to other ReNeW
  panels?)
• Creation of Research Thrusts
• Initial Research Thrust formation by ST Panel
• Open discussion of Research Thrusts
• Completeness, priority, consolidation, synergy
• Size of U.S. effort, research device capabilities
  needed, coupling to international community
• Open discussion as desired

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ST Panel Research Needs Summary and Cross-links

• ST Panel Research Need
• Plasma start up/ramp-up
• Plasma-material interface
• Electron energy transport
• Magnets
• Stability / Steady-State Control
• Integration
• Disruptions
• RF Heating and Current Drive
• Ion scale transport
• Fast Particle Instabilities
• NTMs
• Continuous NBI systems

• ReNeW Cross-cutting Theme
• Theme 2 HPSS Auxiliary systems
• Theme 3 Plasma-material interface
• Theme 2 HPSS Validated Modeling
• Theme 2,3 HPSS Magnets
• Theme 1,2,3 BP/HPSS/PMI Off-normal events
  Control Int. Comp.
• Theme 2 HPSS Integration
• Theme 1,2 - BP/HPSS Off-normal events
• Theme 2,3 HPSS/PMI Auxiliary systems Internal
  Components
• Theme 1 BP Confinement
• Theme 2 BP Off-normal events
• Theme 1,2 BP/HPSS Off-normal events Control
• Theme 2 HPSS Auxiliary systems

• Also, connection between ST-CTF and Theme 4
  materials issues

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Startup Ramp-up / Continuous NBI

• Startup research focused on helicity injection
  RF
• CHI, plasma guns EBW actively being developed
• goal of 0.5 MA in existing facilities, achieved
  0.05 0.16 MA
• must have understanding to project to 1 MA for
  ST goal
• some inductive assist possible
• PF induction will occur naturally
• MIC or retractable OH solenoid, iron core may be
  possible
• NBI planned for Ip ramp-up to 8-10 MA SS current
• need understanding of fast-particle effect on CD
  efficiency
• modeling to give required startup target
  characteristics
• Continuous NBI must resolve gas handling problem
• Li jet neutralization is leading candidate
• need dedicated test facility focused effort to
  develop solution

A.C. Sontag, ORNL
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Plasma-Material Interface Research Needs

• Plasma-Material Interface at High Heat Flux and
  Low Collisionality
• Heat flux management with advanced geometry
  divertors at low aspect ratio
• Need to handle normal (10-40 MW/m2) and
  off-normal heat fluxes over long pulses (3000 s
  and beyond)
• Solutions Advanced geometry (Super X, snowflake
  configurations) high poloidal magnetic flux and
  area expansion divertors, Radiative divertor,
  Radiative mantle, Liquid metal divertor and wall,
  Stochastic edge to be partially tested in MAST
  / MAST-U and NSTX / NSTX-U
• Divertor and first wall solutions must be
  compatible with pedestal and core plasma
  conditions, high-duty cycle operation, nuclear
  environment
• Particle control for continuous low density
  high-performance operation
• Solutions based on cryo-pumping (to be partially
  tested in ITER)
• Liquid metal divertor and wall for low-recycling
  operation (presently tested in LTX and NSTX)
• Impurity transport and control
• Understanding SOL / divertor electron and ion
  heat and particle transport
• Develop understanding and predictive capability
  for SOL / divertor heat and particle width and
  scaling

V. Soukhanovskii, LLNL
V1.2
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Gaps, requirements and possible thrusts for ST
transport research

• Role of ETG, m-tearing, TEM in electron
  transport (B,n,T scaling to CTF/DEMO very
  different)
• Role of ExB shear, magnetic shear, b gradient,
  zonal flows, poloidal rotation
• (ExB likely sufficient for ions Effects on
  electron modes? ITBs, b gradient for ST-DEMO?)
• AE electron transport (GAE ce 10m2/s
  implications for CTF, start-up, any burning
  plasma ?)
• Edge transport with low-recycling wall,
  anomalous ion heating, L-H threshold
• Optimal ST aspect-ratio from transport point of
  view (superior confinement in the ST?)
• Transport studies over extended range of T, n,
  ExB, b
• High low-k, electrostatic magnetic
  fluctuation diagnostic (ETG streamers, ri scale
  islands)
• New experimental and theoretical tools for AE
  electron transport
• Improved power balance and perturbative
  transport tools (EDF diagnostic, fast Te, EBW),
• Electron transport control tools (CTF start-up
  , ST-DEMO)
• New numerical tools for electrostatic and
  magnetic turbulence at large r
• Bt, Ip, Paux upgrades in NSTX and MAST
• Cross-cutting study and control of ETG streamer
  and micro-tearing transport
• Cross-cutting study and control of AE electron
  transport
• Study of DEMO relevant ST transport regimes
• Study of transport in low-recycling/high field ST
  with optimized-A

GAPS
REQUIREMENTS
POSSIBLE THRUSTS
D. Stutman, JHU
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Stability and Steady-State Control Research Needs

• Stability
• ST-CTF (and DEMO) operate at unexplored, uniquely
  low li, high bN/li, levels - stabilization
  understanding near current-driven kink limit,
  sustained qmin 2
• Physics understanding of Vf (can destabilize),
  Ñpi, ÑTi, ni, fast particles (dWkin), li, EPM
  other triggers, role of multiple modes at
  uniquely high bN - increase confidence of
  continuous, stable operation
• low A, high beta, low ni amplifies neoclassical
  trapped particle physics reduced ni is next key
  step for stability, NTV understanding
• Physics understanding of kink/ballooning, RWM,
  ELM stabilization with lithium PFC conditioning,
  liquid metal divertor or walls
• Steady-State Control
• Control Wtot SN fluctuations, disruptivity via
  mode feedback, Vf via NBI NTV, other profile
  control in ST-CTF ( DEMO) stability space with
  significant neutrons, control against Vf, q, Ñp
  transients to support continuous operation
• Greater constraints on CTF, DEMO mode control
  coils, reduced ability to vary equilibria/profiles
  requires operational and research flexibility in
  ITER-era to optimize these non-research devices
  examine moderate 3-D shaping?
• Control techniques suitable for CTF state-space
  mode control, R/T stability evaluation
  techniques, elimination of global mode triggers,
  non-magnetic sensors

S.A. Sabbagh, Columbia U.
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Neoclassical Tearing Modes and STs

• NTM are one of many instabilities that produce
  confinement degradation/disruptions.
• NTMs not unique to STs --- physics program/issues
  overlap with tokamak program
• Largely, the physics is similar, but quantitative
  details are present (higher bootstrap fraction,
  larger flow/flow shear, rho scaling of
  threshold, seeding physics, etc.) ST data feeds
  into establishing important physics.
  Comprehensive theory/model remains elusive.
• Largely, two ways to deal with NTMs
• Avoidance - maintaining elevated q_min --- issue
  is sustainment
• Control tools -- ECCD successful on Tokamaks -
  not available on present day STs
• Research Needs
• Clarification of plasma physics issues --- role
  of flow/flow shear, seeding, etc. --- part of a
  broader theory/simulation/tokamak program
• Demonstration of sustained NTM avoidance.
• Development of control tools -- ECCD availability
  in higher field STs? EBW stabilization?

C. Hegna, UW
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RF Heating and Current Drive

• Higher toroidal field (1-2T or higher) in future
  devices will change RF heating and CD scenarios
• ECH/ECCD Less overdense plasma implies possible
  access to high field side launch for ECH/ECCD
• May be favored for startup/rampup
• EBW Higher frequency required, launcher
  modifications
• Projected CD efficiency good
• HHFW Require operation at reduced harmonics, or
  source development
• Issue alpha particle coupling strong even at
  high harmonics
• Source gap 140 (top end of tetrodes) 300 MHz
  (bottom end of klystrons)
• ICRF Higher field provides access to
  conventional ICRH, MCHCD, even Alfven wave
  heating CD to avoid alpha coupling
• LH possible for highest-field STs (2.5T)?
• Re-evaluation of RF heating and CD scenarios
  necessary
• First need Theory and modeling
• Higher field STs are desirable
• Other RF issues held in common with
  conventional-A tokamaks
• RF-edge issues
• Sheaths, surface waves
• Launchers

D. Majeski, PPPL
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Magnets

• Toroidal field magnet centerpost
• Unshielded or partially shielded?
• Shielding must be minimal to produce good tritium
  breeding fraction
• Possible partial exception fusion-fission hybrid
  
• Replaceable copper centerpost remains baseline
  design
• Single turn
• Demountable designs exist
• Very low impedance source impedance, bussing
  issues
• High current homopolar generators do not yet
  exist
• Current sharing/ripple
• Multiturn
• Must avoid insulators in outer regions few
  designs considered
• All types
• Conductor lifetime in neutron field -
  embrittlement, conductivity (thermal and
  electrical)
• Coolant issues very high flow rates, tritium
  migration into coolant, cooling channel erosion
• Demountable joint integrity under high loads and
  neutron irradiation
• Ohmic solenoid (if present)
• Mineral insulated type
• Neutron tolerance, mechanical integrity

D. Majeski, PPPL
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Gap understanding Energetic particle effects on
heating, current drive and plasma transport

• Multiple beam ion driven TAEs induce strong EP
  (beam ions) transport in NSTX
• NOVA/ORBIT transport predictions require 3
  times higher amplitude than measured to match
  neutrons (Fredrickson'09)
• ST experiments broaden VV parameter space
• to close the gap we need

• develop predictive and measurement
  capabilitiesfor EP transport due to multiple
  collective instabilities

• New effects of (EP driven) GAE induced
  flattening of core electron T profile
  (Stutman,PRL'09)
• May impose strong performance limits on ST
  high beta plasmas
• Stochastic ion heating is important for future
  reactor design optimization
• need to

Understand and control effects of EP driven
instabilities on plasma performance
N. Gorelenkov, PPPL
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Gaps, requirements, possible thrusts for ST
integration, disruptions

• Operation with low normalized density -
  Greenwald fraction 20-30 (vs. present 50-100)
• Operation with up to 50 beam-driven current
  fraction (vs. present 10-20)
• Hot-ion H-mode confinement up to 50 above ITER
  scaling (vs. 10-20 above H98y,2 1)
• Divertor and first-wall heat fluxes at least
  factor of 2 above ITER values (vs. 0.5-1?)
• Impact of integrated plasma regime on stability
  limits, nature and frequency of disruptions
• Disruption avoidance for up to 5-6 orders of
  magnitude longer than present ST
• Divertor/wall pumping and improved fueling for
  density control
• Improved NBI injection geometry and lower
  collisionality for improved efficiency and
  control
• Improved understanding of e/i-transport vs.
  collisionality and BT, IP in high tE H-modes
• Development, demonstration of high-heat-flux
  mitigation compatible with high performance
• Assess stability/control/disruptivity for
  integrated high performance and high power
  exhaust
• Substantial increase in pulse-duration to
  reliably extrapolate disruption probability to
  ST-CTF
• Develop and implement density control tools on
  existing/future STs, evaluate performance
• Implement off-axis NBI on existing/future STs,
  assess AE, fast-ion confinement, NBI-CD
• Increase temperature to study confinement at
  reduced collisionality (via higher BT, IP,
  heating)
• Study high-heat-flux mitigation at increased P/R
  at short-pulse, extend to higher P/R, duration
• Study short-pulse requirements for advanced
  plasma control for above integrated conditions

GAPS
REQUIREMENTS
POSSIBLE THRUSTS
J. Menard, PPPL
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Fusion Nuclear Science Research the Scientific
Stage of CTF before Fusion Energy Development

• Aims to establish the scientific knowledge base
  for fusion energy within DOE Science mission, the
  Stage I of CTF research
• Establish knowledge needed to inform DOE decision
  whether to enter Energy Development via CTF-II
  and CTF-III engineering and technology
  development
• Provide a full fusion nuclear environment to
  extend small scale, fundamental effects research
  to levels needed to close all HFP and TPMI gaps
  identified by FESAC Priorities Report
• Rely on all fusion technology capabilities to
  create the first test components, to carry out
  the tests, to discover new or changed properties,
  and to innovate based on the fusion nuclear
  science knowledge gained
• Rely on FESAC TAP Report recommendations on ST
  RD to get ready
• Recommend common-based benefit-cost-risk
  assessments of options across the aspect ratio
  (ST, Tokamak, or in-between), fusion neutron flux
  (WL 0.01 2.0 MW/m2), and peak divertor heat
  flux (3 10 MW/m2).
• Offer a Science-Based vision of progress toward
  fusion energy development, relying on near term
  ST research upgrades, tokamak research
  upgrades, and high plasma heat flux linear test
  stand capabilities.

M. Peng, ORNL
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Application ST has advantages for Hybrids

• Consensus- de-carbonize electricity before 2050.
  Can fusion help in this mission which will
  dominate mankinds attention on energy?
• Recent advances appear to allow hybrids for waste
  destruction with a greatly reduced number of
  reactors
• Compact fusion driver needed for attractive
  hybrid
• ST advantages
• Less coil mass (lower cost)
• Simpler coil technology
• Much reduced MHD coolant issues (much lower B
  field in fission blanket)
• ST geometry/mass helps to attain greater
  isolation of the fusion driver from the fission
  blanket- easier licensing, less new safety
  concerns
• Easier maintenance
• Easier/faster maintenance could allow component
  replacement after much shorter exposure- greatly
  reduced material issues, reduced testing cycles
• Lower cost of ST arguably allows better economics
  and potentially faster implementation

M. Kotschenreuther, IFS
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Research Thrust (RT) Construction

• Start from initial draft thrusts constructed
  based on ST Panel conference call of 3/12/09
• Summarize RTs on one page
• Stated as 4 main thrusts sub-thrusts (by bullet
  levels)
• No constraint to correlate main/sub-thrusts with
  FESAC TAP Tiers
• New suggestion from Monday supply extra info on
  RTs
• Along the lines of the RT Chapter Template to aid
  document writing
• Opportunity (gap, or issue) RENAME as RESEARCH
  THRUST / SUB-THRUST
• Time frame (short, medium, long) one way to
  avoid describing efforts by dollars
• Work description a few lines of extra detail
• Benefit to Fusion
• Cross-links (with other Themes, etc.)

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Example of longer description of Research Thrusts

• From Theme 3, with new suggested template on 2nd
  row

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ReNeW Document - Research Thrust Chapter Outline
Research Thrust Sample Chapter (6-9 pages)

• Introduction (1-2 pages)
• Scientific importance, opportunities, and urgency
  related to this thrust.
• What important and/or exciting scientific
  questions will this thrust try to answer?
• What opportunities does it realize? (new
  understanding, technical innovation, capabilities
  and partnerships)
• Scientific and Technical Research (3-5 pages)
• Description of each element of thrust, with
  sufficient detail to allow rough schedule and
  cost estimate (is it a decade long activity or a
  3 year task?).
• Description of how elements combine into
  consistent, integrated thrust.
• Benefits for Magnetic Fusion Energy (1-2 pages)
• How would this campaign make progress toward
  magnetic fusion energy?
• What is relation to other thrusts?
• What other scientific benefits (outside of
  fusion?) would be gained?

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ST Research Thrusts Comprise Needs for CTF, DEMO
Integrated, innovative science/technology/theory
for a reduced complexity and cost, high
beta/high confinement device

• Plasma Start-up and Ramp-up Innovations with Low
  Transformer Flux
• Cross-cutting plasma start-up research without a
  center solenoid
• Center solenoid options for low-A plasma startup
• Plasma-Material Interface at High Heat Flux and
  low collisionality/density
• Cross-cutting heat flux control with advanced
  geometry divertors at low-A
• Particle control research for continuous, high
  beta, low ni plasma at low-A
• Cross-cutting study of liquid metal divertor low
  recycling, liquid metal wall
• Understanding SOL / divertor electron / ion heat,
  particle transport at low-A
• Electron / Ion Confinement in High Beta, Broad
  current, Low A Plasma
• Cross-cutting study and control of fast particle
  driven electron transport
• Study of transport in liquid metal wall/high
  field ST with optimized-A
• Cross-cutting research on electrostatic /
  electromagnetic-driven turbulence
• Creating and Understanding Continuous High Beta,
  Low ni ST Plasma
• Stability sustainment / understanding in high
  beta, ultra low-li, optimized-A
• Disruption avoidance / transient mitigation via
  scalable profile / mode control
• Continuous heating / current drive research for
  high beta ST-DEMO plasma
• Center-post magnet technology for high neutron
  flux environment at low-A

Effort Level Guidance Small (black) Moderate
(purple) Large (red)
V1.6
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ST Research Thrusts Comprise Needs for CTF, DEMO
Integrated, innovative science/technology/theory
for a reduced complexity and cost, high
beta/high confinement device

• Plasma Start-up and Ramp-up Innovations with Low
  Transformer Flux
• Cross-cutting plasma start-up research without a
  center solenoid
• Center solenoid options for low-A plasma startup
• Plasma-Material Interface at High Heat Flux and
  low collisionality/density
• Cross-cutting heat flux control with advanced
  geometry divertors at low-A
• Particle control research for continuous, high
  beta, low ni plasma at low-A
• Cross-cutting study of liquid metal divertor low
  recycling, liquid metal wall
• Understanding SOL / divertor electron / ion heat,
  particle transport at low-A
• Electron / Ion Confinement in High Beta, Broad
  current, Low-A Plasma
• Cross-cutting study and control of fast particle
  driven electron transport
• Study of transport in liquid metal wall/high
  field ST with optimized-A
• Cross-cutting research on electrostatic /
  electromagnetic-driven turbulence
• Creating and Understanding Continuous High Beta,
  Low ni ST Plasma
• Stability sustainment / understanding in high
  beta, ultra low-li, optimized-A
• Disruption avoidance / transient mitigation via
  scalable profile / mode control
• Continuous heating / current drive research for
  high beta ST-DEMO plasma
• Center-post magnet technology for high neutron
  flux environment at low-A
• (sub-thrust here?)

Effort Level Guidance Small (black) Moderate
(purple) Large (red)
V1.7
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Magnet RD as a Main Thrust?

• Menard Suggestion for Statement of Research on
  Magnets
• I'm thinking we should note that the magnet work
  is a necessary long-term enabling capability
  rather than a research thrust.
• And we list it as 5th element of thrust list so
  it is not ignored. Realistically, I think it may
  be at risk no matter where it is placed, but
  perhaps the cross-cutting can help.
• I've attached a bullet and sub-bullets on this,
  including cross-cutting.

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ST Research Thrusts to Address ST ITER Era Goals
To establish the scientific and technical
knowledge needed to reduce complexity and cost by
increasing beta and confinement in reliable plasma

• Normally-conducting radiation-tolerant magnets
• Thinly shielded Cu TF magnet (for low-A) in high
  neutron flux environment
• High current electrical joints cross-cutting
  with Theme IV (FDF proposal)
• Mineral-insulated conductor (MIC) for start-up
  solenoid
• MIC may be cross-cutting with Theme-II/III
  internal control coils
• Combining field-coil major upgrades of existing
  devices, design and prototyping of goal-relevant
  TF and solenoid magnets to close the magnet gap.

Effort Level Guidance Small (black) Moderate
(purple) Large (red)
V1.7jem-mp
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Support and Working Slides Follow
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ST Panel Research Thrust Template
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Research Needs Priority FESAC TAP criteria

• Tier 1 Issue Criteria
• Issue is critical for reaching the agreed upon
  goal.
• Resolution of this issue requires major
  extrapolation from current state of knowledge.
• Progress on this issue is essential before other
  research areas can be adequately addressed.
• Scaling is untested and/or physics uncertain.
• Issue contributes in an important way to the
  viability of the concept as a fusion energy
  source.
• Progress would have the broadest impact on fusion
  and plasma science.
• Tier 2 Issue Criteria
• 1. Issue is important for reaching the goal
  and/or for the viability of the concept as a
  fusion energy source.
• 2. Resolution of this issue requires major
  extrapolation from current state of knowledge.
• 3. Only limited scaling data and physics basis
  exist.
• 4. Progress on this issue would be helpful for
  research on other configurations.
• 5. Progress would have a moderate impact on
  fusion science.
• Tier 3 Issue Criteria
• 1. Reaching the goal will require moderate
  extrapolation from current state of knowledge.
• 2. Some scaling data and/or a partially validated
  physics basis are available.
• 3. Present status does not hinder progress on
  other issues.
• 4. Information for resolving this issue may come
  from other parts of the FES program.
• 5. Progress would have a narrow impact on fusion
  science.

• ST Panel Research Need
• Plasma start up/ramp-up
• Plasma-material interface
• Electron energy transport
• Magnets
• Stability / Steady-State Control
• Integration
• Disruptions
• RF Heating and Current Drive
• Ion scale transport
• Fast Particle Instabilities
• NTMs
• Continuous NBI systems

Tier 1
Tier 2
Tier 3
V1.0