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NSTX

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

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  1. 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

  2. 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.

  3. 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

  4. 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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