skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: An overview of recent physics results from NSTX

Journal Article · · Nuclear Fusion
 [1];  [1];  [2];  [3];  [1];  [3];  [4];  [1];  [1];  [3];  [1];  [1];  [5];  [2];  [1];  [6];  [5];  [7];  [8];  [9] more »;  [5];  [10];  [1];  [1];  [11];  [1];  [12];  [13];  [1];  [2];  [1];  [14];  [1]; ORCiD logo [1]; ORCiD logo [1];  [1];  [15];  [4];  [11];  [1];  [13];  [13];  [13];  [16];  [17];  [1];  [1];  [1];  [1];  [18];  [1];  [1];  [19];  [2];  [2];  [1];  [20];  [12];  [21];  [22];  [6];  [1];  [13];  [23];  [24];  [1];  [1];  [1];  [1];  [1];  [19];  [1];  [1];  [1];  [25];  [13];  [13];  [1];  [26];  [27];  [19];  [28];  [25];  [1];  [1];  [1];  [26];  [17];  [1];  [6];  [1];  [1];  [29];  [30];  [15];  [24];  [1];  [1];  [13];  [1];  [25];  [1];  [1];  [1];  [1];  [24];  [1];  [19];  [19];  [15];  [28];  [2];  [31];  [32];  [6];  [29];  [17];  [33];  [28];  [1];  [17];  [13];  [1];  [17];  [6];  [1];  [1];  [1];  [34];  [33];  [1];  [34];  [13];  [1];  [1];  [1];  [1];  [35];  [9];  [1];  [26];  [1];  [1] « less
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Univ. of Illinois, Urbana-Champaign, IL (United States)
  4. Univ. of California, Davis, CA (United States)
  5. Columbia Univ., New York, NY (United States)
  6. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  7. IPP, Garching (Germany)
  8. Univ. of California, San Diego, CA (United States)
  9. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  10. Univ. of Tennessee, Knoxville, TN (United States)
  11. Princeton Univ., NJ (United States)
  12. Purdue Univ., West Lafayette, IN (United States)
  13. General Atomics, San Diego, CA (United States)
  14. Univ. of California, Los Angeles, CA (United States)
  15. Lodestar Research Corp., Boulder, CO (United States)
  16. Johns Hopkins Univ., Baltimore, MD (United States)
  17. University of Wisconsin, Madison, WI (United States)
  18. Univ. of Washington, Seattle, WA (United States)
  19. Princeton University, NJ (United States)
  20. CompX, Del Mar, CA (United States)
  21. Univ. of California, Irvine, CA (United States)
  22. National Inst. for Fusion Science, Toki (Japan)
  23. XCEL, Oak Ridge, TN (United States)
  24. University of Washington, Seattle, WA (United States)
  25. University of California, Los Angeles, CA (United States)
  26. Nova Photonics, Princeton, NJ (United States)
  27. University of California, Irvine, CA (United States)
  28. University of Illinois, Urbana-Champaign, IL (United States)
  29. University of Colorado, Boulder, CO (United States)
  30. University of California, Davis, CA (United States)
  31. Columbia University, New York, NY (United States)
  32. Lehigh University, Bethlehem, PA (United States)
  33. Purdue University, West Lafayette, IN (United States)
  34. Johns Hopkins University, Baltimore, MD (United States)
  35. University of Tennessee, Knoxville, TN (United States)
+ Show Author Affiliations

Currently, the National Spherical Torus Experiment (NSTX) is being upgraded to operate at twice the toroidal field and plasma current (up to 1 T and 2 MA), with a second, more tangentially aimed neutral beam (NB) for current and rotation control, allowing for pulse lengths up to 5 s. Recent NSTX physics analyses have addressed topics that will allow NSTX-Upgrade to achieve the research goals critical to a Fusion Nuclear Science Facility. These include producing stable, 100% non-inductive operation in high-performance plasmas, assessing plasma-material interface (PMI) solutions to handle the high heat loads expected in the next-step devices and exploring the unique spherical torus (ST) parameter regimes to advance predictive capability. Non-inductive operation and current profile control in NSTX-U will be facilitated by co-axial helicity injection (CHI) as well as radio frequency (RF) and NB heating. CHI studies using NIMROD indicate that the reconnection process is consistent with the 2D Sweet-Parker theory. Full-wave AORSA simulations show that RF power losses in the scrape-off layer (SOL) increase significantly for both NSTX and NSTX-U when the launched waves propagate in the SOL. Moreover, Toroidal Alfven eigenmode avalanches and higher frequency Alfven eigenmodes can affect NB-driven current through energy loss and redistribution of fast ions. The inclusion of rotation and kinetic resonances, which depend on collisionality, is necessary for predicting experimental stability thresholds of fast growing ideal wall and resistive wall modes. Neutral beams and neoclassical toroidal viscosity generated from applied 3D fields can be used as actuators to produce rotation profiles optimized for global stability. DEGAS-2 has been used to study the dependence of gas penetration on SOL temperatures and densities for the MGI system being implemented on the Upgrade for disruption mitigation. PMI studies have focused on the effect of ELMs and 3D fields on plasma detachment and heat flux handling. Simulations indicate that snowflake and impurity seeded radiative divertors are candidates for heat flux mitigation in NSTX-U. Studies of lithium evaporation on graphite surfaces indicate that lithium increases oxygen surface concentrations on graphite, and deuterium-oxygen affinity, which increases deuterium pumping and reduces recycling. In situ and test-stand experiments of lithiated graphite and molybdenum indicate temperature-enhanced sputtering, although that test-stand studies also show the potential for heat flux reduction through lithium vapour shielding. Non-linear gyro kinetic simulations have indicated that ion transport can be enhanced by a shear-flow instability, and that non-local effects are necessary to explain the observed rapid changes in plasma turbulence. Predictive simulations have shown agreement between a microtearing-based reduced transport model and the measured electron temperatures in a microtearing unstable regime. Finally, two Alfven eigenmode-driven fast ion transport models have been developed and successfully benchmarked against NSTX data. Upgrade construction is moving on schedule with initial physics research operation of NSTX-U planned for mid-2015.

Research Organization:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC52-07NA27344; AC02-09CH11466
OSTI ID:
1888620
Alternate ID(s):
OSTI ID: 1256734
Report Number(s):
LLNL-JRNL-840084; PPPL-5092; 1061331; TRN: US2309907
Journal Information:
Nuclear Fusion, Vol. 55, Issue 10; ISSN 0029-5515
Publisher:
IOP ScienceCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 22 works
Citation information provided by
Web of Science

References (75)

Mitigation of Alfvén Activity in a Tokamak by Externally Applied Static 3D Fields journal June 2013
A description of the full-particle-orbit-following SPIRAL code for simulating fast-ion experiments in tokamaks journal January 2013
Computation of three-dimensional tokamak and spherical torus equilibria journal May 2007
Varying the pre-discharge lithium wall coatings to alter the characteristics of the ELM-free H-mode pedestal in NSTX journal July 2013
Geometrical properties of a “snowflake” divertor journal June 2007
Fast-ion energy loss during TAE avalanches in the National Spherical Torus Experiment journal December 2012
Type-I ELM filamentary substructure on the JET divertor target journal August 2011
Linear stability and nonlinear dynamics of the fishbone mode in spherical tokamaks journal October 2013
An Eulerian gyrokinetic-Maxwell solver journal April 2003
A reduced fast ion transport model for the tokamak transport code TRANSP journal April 2014
Empiricial scaling of inter-ELM power widths in ASDEX Upgrade and JET journal July 2013
Measured improvement of global magnetohydrodynamic mode stability at high-beta, and in reduced collisionality spherical torus plasmas journal May 2014
Internal amplitude, structure and identification of compressional and global Alfvén eigenmodes in NSTX journal March 2013
Electron temperature gradient driven turbulence journal May 2000
Triggered Confinement Enhancement and Pedestal Expansion in High-Confinement-Mode Discharges in the National Spherical Torus Experiment journal September 2010
Core transport of lithium and carbon in ELM-free discharges with lithium wall conditioning in NSTX journal July 2013
Lithium coatings on NSTX plasma facing components and its effects on boundary control, core plasma performance, and operation journal November 2010
Resistive magnetohydrodynamic simulations of helicity-injected startup plasmas in National Spherical Torus eXperiment journal September 2013
Nonlinear flow generation by electrostatic turbulence in tokamaks journal July 2010
Design and operation of a fast electromagnetic inductive massive gas injection valve for NSTX-U journal November 2014
Steepest-descent moment method for three-dimensional magnetohydrodynamic equilibria journal January 1983
Dynamic modeling of transport and positional control of tokamaks journal October 1986
Physics issues of compact drift optimized stellarators journal June 2001
Transition to ELM-free improved H-mode by lithium deposition on NSTX graphite divertor surfaces journal June 2009
Neutral Gas Transport Modeling with DEGAS 2 journal January 1994
Full wave simulations of fast wave heating losses in the scrape-off layer of NSTX and NSTX-U journal May 2014
Edge-Localized-Mode Suppression through Density-Profile Modification with Lithium-Wall Coatings in the National Spherical Torus Experiment journal August 2009
Edge microstability of NSTX plasmas without and with lithium-coated plasma-facing components journal September 2013
Magnetic reconnection process in transient coaxial helicity injection journal September 2013
Non-linear modulation of short wavelength compressional Alfvén eigenmodes journal April 2013
Global δf particle simulation of neoclassical transport and ambipolar electric field in general geometry journal December 2004
Nanostructuring of molybdenum and tungsten surfaces by low-energy helium ions
  • De Temmerman, Gregory; Bystrov, Kirill; Zielinski, Jakub J.
  • Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, Vol. 30, Issue 4 https://doi.org/10.1116/1.4731196
journal July 2012
Observation of Compressional Alfvén Modes During Neutral-Beam Heating on the National Spherical Torus Experiment journal September 2001
Benchmarking kinetic calculations of resistive wall mode stability journal May 2014
The tokamak Monte Carlo fast ion module NUBEAM in the National Transport Code Collaboration library journal June 2004
Momentum-Transport Studies in High E × B Shear Plasmas in the National Spherical Torus Experiment journal August 2008
High-speed imaging of edge turbulence in NSTX journal December 2003
Self-consistent equilibrium model of low aspect-ratio toroidal plasma with energetic beam ions journal August 2003
Overview of physics results from the conclusive operation of the National Spherical Torus Experiment journal September 2013
Resistive Wall Mode in Collisionless Quasistationary Plasmas journal September 2004
The effect of the fast-ion profile on Alfvén eigenmode stability journal August 2013
Non-inductive plasma start-up on NSTX and projections to NSTX-U using transient CHI journal June 2013
Progress in characterization of the pedestal stability and turbulence during the edge-localized-mode cycle on National Spherical Torus Experiment journal August 2013
Neoclassical flows and transport in nonaxisymmetric toroidal plasmas journal January 1983
Nonlinear magnetohydrodynamics simulation using high-order finite elements journal March 2004
Prospects for pilot plants based on the tokamak, spherical tokamak and stellarator journal August 2011
Point-Source Helicity Injection Current Drive System for the Pegasus Toroidal Experiment journal November 2008
Reduced model prediction of electron temperature profiles in microtearing-dominated National Spherical Torus eXperiment plasmas journal August 2014
MAST Accomplishments and Upgrade for Fusion Next-Steps journal March 2014
Magnetic topology, disruptions and electron heat transport journal January 1986
Numerical simulation of ion cyclotron waves in tokamak plasmas journal January 1999
Fast-wave power flow along SOL field lines in NSTX and the associated power deposition profile across the SOL in front of the antenna journal July 2013
Type-I ELM power deposition profile width and temporal shape in JET journal August 2011
The relationships between edge localized modes suppression, pedestal profiles and lithium wall coatings in NSTX journal September 2011
High density Langmuir probe array for NSTX scrape-off layer measurements under lithiated divertor conditions journal October 2010
Overview of the physics and engineering design of NSTX upgrade journal July 2012
Electron cyclotron current drive efficiency in general tokamak geometry journal October 2003
Edge-plasma models and characteristics for magnetic fusion energy devices journal July 2002
Simulation of non-resonant internal kink mode with toroidal rotation in the National Spherical Torus Experiment journal July 2013
1.5D quasilinear model and its application on beams interacting with Alfvén eigenmodes in DIII-D journal September 2012
Experimental demonstration of tokamak inductive flux saving by transient coaxial helicity injection on national spherical torus experiment journal September 2011
The role of kinetic effects, including plasma rotation and energetic particles, in resistive wall mode stability journal August 2010
NOVA: A nonvariational code for solving the MHD stability of axisymmetric toroidal plasmas journal July 1987
Lithium sputtering from lithium-coated plasma facing components in the NSTX divertor journal August 2015
Progress in understanding the enhanced pedestal H-mode in NSTX journal June 2014
Calculations of two-fluid magnetohydrodynamic axisymmetric steady-states journal November 2009
Correlation between Electron Transport and Shear Alfvén Activity in the National Spherical Torus Experiment journal March 2009
Advances in high-harmonic fast wave physics in the National Spherical Torus Experiment journal May 2010
Results of an International Study on a High-Volume Plasma-Based Neutron Source for Fusion Blanket Development journal January 1996
All-orders spectral calculation of radio-frequency heating in two-dimensional toroidal plasmas journal May 2001
Plasma simulation studies using multilevel physics models journal May 1999
Effect of a deuterium gas puff on the edge plasma in NSTX journal July 2014
A fully implicit, time dependent 2-D fluid code for modeling tokamak edge plasmas journal December 1992
Characteristics of low-q disruptions in PBX journal November 1988
Liquid-metal plasma-facing component research on the National Spherical Torus Experiment journal November 2013

Cited By (8)

Effect of wall boundary on the scrape-off layer losses of high harmonic fast wave in NSTX and NSTX-U journal June 2019
Feedback control design for non-inductively sustained scenarios in NSTX-U using TRANSP journal April 2017
Plasma boundary shape control and real-time equilibrium reconstruction on NSTX-U journal January 2018
Recent progress in understanding electron thermal transport in NSTX journal March 2017
Real-time capable modeling of neutral beam injection on NSTX-U using neural networks journal March 2019
Effects of the applied magnetic fields with various toroidal phase differences on the neoclassical toroidal viscosity in JT-60SA journal October 2018
Observation of quasi-coherent edge fluctuations in Ohmic plasmas on National Spherical Torus Experiment journal April 2016
Unraveling the surface chemistry processes in lithiated and boronized plasma material interfaces under extreme conditions journal July 2018

Similar Records

Overview of results from the National Spherical Torus Experiment (NSTX)
Journal Article · Thu Jan 01 00:00:00 EST 2009 · Nuclear Fusion · OSTI ID:1888620
+12 more
Overview of recent physics results from the National Spherical Torus Experiment (NSTX)
Journal Article · Mon Oct 01 00:00:00 EDT 2007 · Nuclear Fusion · OSTI ID:1888620
+146 more
Recent Physics Results from NSTX
Conference · Thu Oct 05 00:00:00 EDT 2006 · OSTI ID:1888620
+41 more

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
NSTX
spherical torus
overview
toroidal plasmas
transport
simulation
code
disruptions
turbulence
tokamaks
geometry
models