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NSTX. Supported by. Developing the Core Physics Scenarios For Next Step STs. Stefan Gerhardt Friday AM Talk at 2011 APS DPP. Columbia U CompX General Atomics FIU INL Johns Hopkins U LANL LLNL Lodestar MIT Nova Photonics New York U ORNL PPPL Princeton U Purdue U SNL

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NSTX

Supported by

Developing the Core Physics Scenarios For Next Step STs

Stefan Gerhardt

Friday AM Talk at 2011 APS DPP

Columbia U

CompX

General Atomics

FIU

INL

Johns Hopkins U

LANL

LLNL

Lodestar

MIT

Nova Photonics

New York U

ORNL

PPPL

Princeton U

Purdue U

SNL

Think Tank, Inc.

UC Davis

UC Irvine

UCLA

UCSD

U Colorado

U Illinois

U Maryland

U Rochester

U Washington

U Wisconsin

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

JAEA

Hebrew U

Ioffe Inst

RRC Kurchatov Inst

TRINITI

NFRI

KAIST

POSTECH

ASIPP

ENEA, Frascati

CEA, Cadarache

IPP, Jülich

IPP, Garching

ASCR, Czech Rep


Outline of Talk (20 slides)

  • Intro (4 slides)

    • Describe why STs are (potentially) useful. (1 slide)

    • The NSTX facility. (1 slide)

      • Emphasize upgrades in the past 3-4 years that contribute to “advanced” plasmas (routine RMW control, Lithium, improved control).

    • What is the present “best” performance in NSTX. (2 slides)

      • Database analysis of operating space, example discharges.

  • Describe results in three interacting areas (10 slides):

    • Transport (2 slides)

      • Lowest order scanlings….effect of Li?

    • Current drive (4 slides)

      • Cases that are approximately classical without *AE activity.

      • Phenomenological modeling of current redistribution with TAE Avalanches.

      • Achieved non-inductive fractions in NSTX

    • Stability (4 slides)

      • Importance of elevated qmin>1 to avoid core kink/tearing

      • Strong shaping, broad profiles.

      • RWM control

  • NSTX-Upgrade Simulations (4 slides)

    • Describe the methods (1 slide)

    • Example profiles for 100% non-inductive cases w/ Pinj=12.6 MW, BT=1.0T, including thermal profile and confinement scaling sensitivity. (1 slide)

    • Compare a broad range of upgrade scenarios to existing NSTX parameters (2 slides)

      • Separate 100% non-inducive and high-current partial inductive.

      • Emphasize what is similar (bN, H), and what is better (lower collisionality, elevated qmin)

  • 2 Themes:

  • How facility improvements help with scenarios

  • How physics results support the modeling.


How Recent Facility Improvements Interact to Improve Performance

Eliminate ELMs

Broaden the Conductivity Profile

Reduced PCS Latency

Increase k

Elevate qmin

Avoid core n=1 modes

Lower li

Lithium Conditioning of PFCs

Increase Bootstrap Current

Increase Non-Inductive Fraction

Improved Electron Confinement

n=1 Control

RWM & DEFC

Increase NBCD

Reduce bN Limit

Maintain Rotation

Increase Projected Fusion Gain

Maintain or Increase bN

Eliminate Rapidly Growing RWMs


What is needed.

  • Most of the data is well analyzed.

  • Could use:

    • Finish upgrade modeling (SPG work).

    • Conclusion on the Li vs. no-Li confinement trends. Does collisionality explain everything? Pedestal vs. Core?

    • NSTX-U modeling assumes that ion transport remains neoclassical. Do we expect this to be true? GTS calculations started?

    • Elongation scaling of the no-wall limit in NSTX/NSTX-U relevant plasmas.

    • Conditions for TAE Avalanche onset in H-mode plasmas.

    • Is it necessary to say anything about disruptions…their frequency or predictability?


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