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

This content will become publicly available on May 27, 2021

Title: Real-time pedestal optimization and ELM control with 3D fields and gas flows on DIII-D

Abstract

The capabilities of the DIII-D tokamak's plasma control system (PCS) were expanded to allow for pedestal optimization and edge localized mode (ELM) control. Three proof of principle control schemes are presented herein that were successfully implemented and tested. These use multiple inputs from real-time (RT) diagnostics like a $$D_\alpha$$ based ELM monitor and edge profile measurements from Thomson scattering (TS) as well as 3D, i.e. non-axisymmetric, magnetic fields and gas puffs as actuators to regulate the density pedestal. The first scheme targets to optimize the access of ELM suppression induced by non-axisymmetric magnetic perturbations (MPs). The conducted set of experiments identifies a path dependence of plasma confinement on the applied MP amplitude. The controller aims to transition into ELM suppression at the minimum 3D field amplitude and reduces it further afterwards, allowing for partial confinement recovery. Another pedestal control scheme is deployed to compensate the density 'pump-out' in MP ELM suppression by regulating the gas puff. This uses RT TS diagnostic data, extracting the pedestal height from the electron density ($$n_{\mathrm{e}}$$) profiles and enables studies of the transition into and out of MP ELM suppression at constant density. A limit cycle behavior of edge rotation and MP amplitude persists under these conditions. The third control scheme combines MPs and gas puffs as actuators to perform pedestal density trajectory control to access Super high confinement mode (H-mode) and furthermore, allowing the integration of a radiative divertor in this regime. While MPs mainly impact the pedestal top density, the control scheme allows to loosen the tight coupling of pedestal top and separatrix density evolution. With respect to ITER, the achieved results emphasize the need for an advanced control system to keep MP amplitude close to but above the ELM suppression threshold at all times, enabling high confinement and, respectively, at high fusion energy gain factor (Q). Lastly, pedestal control enables detailed physics studies in present-day tokamaks and allows the exploration of core-edge integrated plasma scenarios.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [2];  [4]; ORCiD logo [3]; ORCiD logo [3]; ORCiD logo [2];  [2]; ORCiD logo [3]; ORCiD logo [2]; ORCiD logo [2]; ORCiD logo [5]; ORCiD logo [6]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Princeton Univ., NJ (United States)
  2. General Atomics, San Diego, CA (United States)
  3. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  6. Princeton Univ., NJ (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States); Princeton Univ., NJ (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Contributing Org.:
DIII-D team
OSTI Identifier:
1631424
Alternate Identifier(s):
OSTI ID: 1615725; OSTI ID: 1631484
Grant/Contract Number:  
FC02-04ER54698; AC02-09CH11466; AC52-07NA27344; AC05-00OR22725; SC0015878; SC0015480
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 60; Journal Issue: 7; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Tokamak; super H-mode; edge localized modes; 3D fields

Citation Formats

Laggner, F. M., Eldon, D., Nelson, A. O., Paz-Soldan, C., Bortolon, A., Evans, T. E., Fenstermacher, M. E., Grierson, B. A., Hu, Q., Humphreys, D. A., Hyatt, A. W., Nazikian, R., Meneghini, O., Snyder, P. B., Unterberg, E. A., and Kolemen, E. Real-time pedestal optimization and ELM control with 3D fields and gas flows on DIII-D. United States: N. p., 2020. Web. doi:10.1088/1741-4326/ab88e1.
Laggner, F. M., Eldon, D., Nelson, A. O., Paz-Soldan, C., Bortolon, A., Evans, T. E., Fenstermacher, M. E., Grierson, B. A., Hu, Q., Humphreys, D. A., Hyatt, A. W., Nazikian, R., Meneghini, O., Snyder, P. B., Unterberg, E. A., & Kolemen, E. Real-time pedestal optimization and ELM control with 3D fields and gas flows on DIII-D. United States. doi:https://doi.org/10.1088/1741-4326/ab88e1
Laggner, F. M., Eldon, D., Nelson, A. O., Paz-Soldan, C., Bortolon, A., Evans, T. E., Fenstermacher, M. E., Grierson, B. A., Hu, Q., Humphreys, D. A., Hyatt, A. W., Nazikian, R., Meneghini, O., Snyder, P. B., Unterberg, E. A., and Kolemen, E. Wed . "Real-time pedestal optimization and ELM control with 3D fields and gas flows on DIII-D". United States. doi:https://doi.org/10.1088/1741-4326/ab88e1.
@article{osti_1631424,
title = {Real-time pedestal optimization and ELM control with 3D fields and gas flows on DIII-D},
author = {Laggner, F. M. and Eldon, D. and Nelson, A. O. and Paz-Soldan, C. and Bortolon, A. and Evans, T. E. and Fenstermacher, M. E. and Grierson, B. A. and Hu, Q. and Humphreys, D. A. and Hyatt, A. W. and Nazikian, R. and Meneghini, O. and Snyder, P. B. and Unterberg, E. A. and Kolemen, E.},
abstractNote = {The capabilities of the DIII-D tokamak's plasma control system (PCS) were expanded to allow for pedestal optimization and edge localized mode (ELM) control. Three proof of principle control schemes are presented herein that were successfully implemented and tested. These use multiple inputs from real-time (RT) diagnostics like a $D_\alpha$ based ELM monitor and edge profile measurements from Thomson scattering (TS) as well as 3D, i.e. non-axisymmetric, magnetic fields and gas puffs as actuators to regulate the density pedestal. The first scheme targets to optimize the access of ELM suppression induced by non-axisymmetric magnetic perturbations (MPs). The conducted set of experiments identifies a path dependence of plasma confinement on the applied MP amplitude. The controller aims to transition into ELM suppression at the minimum 3D field amplitude and reduces it further afterwards, allowing for partial confinement recovery. Another pedestal control scheme is deployed to compensate the density 'pump-out' in MP ELM suppression by regulating the gas puff. This uses RT TS diagnostic data, extracting the pedestal height from the electron density ($n_{\mathrm{e}}$) profiles and enables studies of the transition into and out of MP ELM suppression at constant density. A limit cycle behavior of edge rotation and MP amplitude persists under these conditions. The third control scheme combines MPs and gas puffs as actuators to perform pedestal density trajectory control to access Super high confinement mode (H-mode) and furthermore, allowing the integration of a radiative divertor in this regime. While MPs mainly impact the pedestal top density, the control scheme allows to loosen the tight coupling of pedestal top and separatrix density evolution. With respect to ITER, the achieved results emphasize the need for an advanced control system to keep MP amplitude close to but above the ELM suppression threshold at all times, enabling high confinement and, respectively, at high fusion energy gain factor (Q). Lastly, pedestal control enables detailed physics studies in present-day tokamaks and allows the exploration of core-edge integrated plasma scenarios.},
doi = {10.1088/1741-4326/ab88e1},
journal = {Nuclear Fusion},
number = 7,
volume = 60,
place = {United States},
year = {2020},
month = {5}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on May 27, 2021
Publisher's Version of Record

Save / Share:

Works referenced in this record:

Computation of three-dimensional tokamak and spherical torus equilibria
journal, May 2007

  • Park, Jong-kyu; Boozer, Allen H.; Glasser, Alan H.
  • Physics of Plasmas, Vol. 14, Issue 5
  • DOI: 10.1063/1.2732170

Suppression of Edge Localized Modes in High-Confinement KSTAR Plasmas by Nonaxisymmetric Magnetic Perturbations
journal, July 2012


Initial results of the high resolution edge Thomson scattering upgrade at DIII-D
journal, October 2012

  • Eldon, D.; Bray, B. D.; Deterly, T. M.
  • Review of Scientific Instruments, Vol. 83, Issue 10
  • DOI: 10.1063/1.4738656

Real-time dispersion interferometry for density feedback in fusion devices
journal, September 2018


On the Minimum Size of DEMO
journal, October 2010

  • Zohm, Hartmut
  • Fusion Science and Technology, Vol. 58, Issue 2
  • DOI: 10.13182/FST10-06

Controlling marginally detached divertor plasmas
journal, May 2017


Diagnostics and control for the steady state and pulsed tokamak DEMO
journal, January 2016


Exploration of the Super H-mode regime on DIII-D and potential advantages for burning plasma devices
journal, March 2016

  • Solomon, W. M.; Snyder, P. B.; Bortolon, A.
  • Physics of Plasmas, Vol. 23, Issue 5
  • DOI: 10.1063/1.4944822

Multi-mode error field correction on the DIII-D tokamak
journal, March 2003


The spectral basis of optimal error field correction on DIII-D
journal, April 2014


Edge localized modes and the pedestal: A model based on coupled peeling–ballooning modes
journal, May 2002

  • Snyder, P. B.; Wilson, H. R.; Ferron, J. R.
  • Physics of Plasmas, Vol. 9, Issue 5
  • DOI: 10.1063/1.1449463

Actuator and diagnostic requirements of the ITER Plasma Control System
journal, December 2012


The dud detector: An empirically-based real-time algorithm to save neutron and T budgets during JET DT operation
journal, September 2019


A universal instability of many-dimensional oscillator systems
journal, May 1979


Assessment of controllers and scenario control performance for ITER first plasma
journal, September 2019


Real-time feedback control of the plasma density profile on ASDEX Upgrade
journal, March 2011


Physics requirements for the ITER plasma control system
journal, July 2010


Study of in-vessel nonaxisymmetric ELM suppression coil concepts for ITER
journal, January 2008


Control of plasma stored energy for burn control using DIII-D in-vessel coils
journal, April 2015


A framework for the assessment and control of ITER main chamber heat loads
journal, February 2020


Real-time control of divertor detachment in H-mode with impurity seeding using Langmuir probe feedback in JET-ITER-like wall
journal, February 2017

  • Guillemaut, C.; Lennholm, M.; Harrison, J.
  • Plasma Physics and Controlled Fusion, Vol. 59, Issue 4
  • DOI: 10.1088/1361-6587/aa5951

Model-based real-time power flux estimator for the ITER first wall
journal, December 2018


Critical edge parameters for H-mode transition in DIII-D
journal, May 1998


Conceptual design of the tangentially viewing combined interferometer-polarimeter for ITER density measurements
journal, April 2013

  • Van Zeeland, M. A.; Boivin, R. L.; Brower, D. L.
  • Review of Scientific Instruments, Vol. 84, Issue 4
  • DOI: 10.1063/1.4798602

Control-oriented modeling of the plasma particle density in tokamaks and application to real-time density profile reconstruction
journal, January 2018


Characteristics of type I ELM energy and particle losses in existing devices and their extrapolation to ITER
journal, August 2003


Experimental studies of high-confinement mode plasma response to non-axisymmetric magnetic perturbations in ASDEX Upgrade
journal, November 2016


Development of ITER-relevant plasma control solutions at DIII-D
journal, July 2007


Work-flow process from simulation to operation for the Plasma Control System for the ITER first plasma
journal, September 2019


Preparing the Plasma Control System final design for ITER first plasma operations
journal, April 2018


Integrated modeling applications for tokamak experiments with OMFIT
journal, July 2015


Nonlinear Transition from Mitigation to Suppression of the Edge Localized Mode with Resonant Magnetic Perturbations in the EAST Tokamak
journal, September 2016


Plasma density control in real-time on the COMPASS tokamak
journal, October 2015


Novel aspects of plasma control in ITER
journal, February 2015

  • Humphreys, D.; Ambrosino, G.; de Vries, P.
  • Physics of Plasmas, Vol. 22, Issue 2
  • DOI: 10.1063/1.4907901

Edge-localized-modes in tokamaks
journal, September 2014


An advanced plasma control system for the DIII-D tokamak
conference, January 1992

  • Ferron, J. R.; Kellman, A.; McKee, E.
  • [Proceedings] The 14th IEEE/NPSS Symposium Fusion Engineering
  • DOI: 10.1109/FUSION.1991.218736

Multiparameter measurement utilizing poloidal polarimeter for burning plasma reactor
conference, January 2014

  • Imazawa, Ryota; Kawano, Yasunori; Itami, Kiyoshi
  • FUSION REACTOR DIAGNOSTICS: Proceedings of the International Conference, AIP Conference Proceedings
  • DOI: 10.1063/1.4894025

Real‐time digital control, data acquisition, and analysis system for the DIII‐D multipulse Thomson scattering diagnostic
journal, October 1990

  • Greenfield, C. M.; Campbell, G. L.; Carlstrom, T. N.
  • Review of Scientific Instruments, Vol. 61, Issue 10
  • DOI: 10.1063/1.1141615

Effect of island overlap on edge localized mode suppression by resonant magnetic perturbations in DIII-D
journal, May 2008

  • Fenstermacher, M. E.; Evans, T. E.; Osborne, T. H.
  • Physics of Plasmas, Vol. 15, Issue 5
  • DOI: 10.1063/1.2901064

Access to a New Plasma Edge State with High Density and Pressures using the Quiescent H Mode
journal, September 2014


Current status of the upgraded DIII-D real-time digital plasma control system
journal, June 2004


Real time control developments at JET in preparation for deuterium-tritium operation
journal, November 2017


Advances in radiated power control at DIII-D
journal, January 2019


3D field phase-space control in tokamak plasmas
journal, September 2018


ELM frequency feedback control on JET
journal, April 2015


Real‐time, vibration‐compensated CO 2 interferometer operation on the DIII‐D tokamak
journal, July 1988

  • Carlstrom, T. N.; Ahlgren, D. R.; Crosbie, J.
  • Review of Scientific Instruments, Vol. 59, Issue 7
  • DOI: 10.1063/1.1139726

Implementation strategy for the ITER plasma control system
journal, October 2015


The ITER disruption mitigation trigger: developing its preliminary design
journal, January 2018


High fusion performance in Super H-mode experiments on Alcator C-Mod and DIII-D
journal, June 2019


Design of the ITER In-Vessel Coils
journal, July 2011

  • Neumeyer, C.; Brooks, A.; Bryant, L.
  • Fusion Science and Technology, Vol. 60, Issue 1
  • DOI: 10.13182/FST11-A12333

Design and operation of the multipulse Thomson scattering diagnostic on DIII‐D (invited)
journal, October 1992

  • Carlstrom, T. N.; Campbell, G. L.; DeBoo, J. C.
  • Review of Scientific Instruments, Vol. 63, Issue 10
  • DOI: 10.1063/1.1143545

Update on Design of the ITER In-Vessel Coils
journal, August 2013

  • Daly, E. F.; Ioki, K.; Loarte, A.
  • Fusion Science and Technology, Vol. 64, Issue 2
  • DOI: 10.13182/FST13-A18073

Suppression of Large Edge-Localized Modes in High-Confinement DIII-D Plasmas with a Stochastic Magnetic Boundary
journal, June 2004