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Title: Integrated current profile, normalized beta and NTM control in DIII-D

Abstract

There is an increasing need for integrating individual plasma-control algorithms with the ultimate goal of simultaneously regulating more than one plasma property. Some of these integrated-control solutions should have the capability of arbitrating the authority of the individual plasma-control algorithms over the available actuators within the tokamak. Such decision-making process must run in real time since its outcome depends on the plasma state. Therefore, control architectures including supervisory and/or exception-handling algorithms will play an essential role in future fusion reactors like ITER. However, most plasma-control experiments in present devices have focused so far on demonstrating control solutions for isolated objectives. In this work, initial experimental results are reported for simultaneous current-profile control, normalized-beta control, and Neoclassical Tearing Mode (NTM) suppression in DIII-D. Neutral beam injection (NBI), electron-cyclotron (EC) heating & current drive (H&CD), and plasma current modulation are the actuation methods. The NBI power and plasma current are always modulated by the Profile Control category within the DIII-D Plasma Control System (PCS) in order to control both the current profile and the normalized beta. EC H&CD is utilized by either the Profile Control or the Gyrotron categories within the DIII-D PCS as dictated by the Off-Normal and Fault Response (ONFR)more » system, which monitors the occurrence of an NTM and regulates the authority over the gyrotrons. The total EC power and poloidal mirror angles are the gyrotron-related actuation variables. When no NTM suppression is required, the gyrotrons are used by the Profile Control category, but when NTM suppression is required, the ONFR transfers the authority over the gyrotrons to the NTM stabilization algorithm located in the Gyrotron category. Initial experimental results show that simultaneous control of different aspects of the plasma dynamics may improve the overall control and plasma performances. Also, the potential of the ONFR system to successfully integrate competing control algorithms is demonstrated.« less

Authors:
 [1];  [1]; ORCiD logo [1];  [2];  [2];  [2];  [2];  [2]; ORCiD logo [2];  [2];  [2]
+ Show Author Affiliations
  1. Lehigh Univ., Bethlehem, PA (United States)
  2. General Atomics, San Diego, CA (United States)
Publication Date:
Research Org.:
Lehigh Univ., Bethlehem, PA (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1611479
Grant/Contract Number:  
SC0010661; FC02-04ER54698
Resource Type:
Accepted Manuscript
Journal Name:
Fusion Engineering and Design
Additional Journal Information:
Journal Volume: 146; Journal Issue: A; Journal ID: ISSN 0920-3796
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; plasma control; integrated control; NTM control; current profile control; beta control; supervisory control

Citation Formats

Pajares, A., Wehner, W. P., Schuster, E., Eidietis, N., Welander, A., La Haye, R., Ferron, J., Barr, J., Walker, M., Humphreys, D., and Hyatt, A. Integrated current profile, normalized beta and NTM control in DIII-D. United States: N. p., 2019. Web. doi:10.1016/j.fusengdes.2019.01.022.
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Pajares, A., Wehner, W. P., Schuster, E., Eidietis, N., Welander, A., La Haye, R., Ferron, J., Barr, J., Walker, M., Humphreys, D., & Hyatt, A. Integrated current profile, normalized beta and NTM control in DIII-D. United States. https://doi.org/10.1016/j.fusengdes.2019.01.022
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Pajares, A., Wehner, W. P., Schuster, E., Eidietis, N., Welander, A., La Haye, R., Ferron, J., Barr, J., Walker, M., Humphreys, D., and Hyatt, A. Sat . "Integrated current profile, normalized beta and NTM control in DIII-D". United States. https://doi.org/10.1016/j.fusengdes.2019.01.022. https://www.osti.gov/servlets/purl/1611479.
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@article{osti_1611479,
title = {Integrated current profile, normalized beta and NTM control in DIII-D},
author = {Pajares, A. and Wehner, W. P. and Schuster, E. and Eidietis, N. and Welander, A. and La Haye, R. and Ferron, J. and Barr, J. and Walker, M. and Humphreys, D. and Hyatt, A.},
abstractNote = {There is an increasing need for integrating individual plasma-control algorithms with the ultimate goal of simultaneously regulating more than one plasma property. Some of these integrated-control solutions should have the capability of arbitrating the authority of the individual plasma-control algorithms over the available actuators within the tokamak. Such decision-making process must run in real time since its outcome depends on the plasma state. Therefore, control architectures including supervisory and/or exception-handling algorithms will play an essential role in future fusion reactors like ITER. However, most plasma-control experiments in present devices have focused so far on demonstrating control solutions for isolated objectives. In this work, initial experimental results are reported for simultaneous current-profile control, normalized-beta control, and Neoclassical Tearing Mode (NTM) suppression in DIII-D. Neutral beam injection (NBI), electron-cyclotron (EC) heating & current drive (H&CD), and plasma current modulation are the actuation methods. The NBI power and plasma current are always modulated by the Profile Control category within the DIII-D Plasma Control System (PCS) in order to control both the current profile and the normalized beta. EC H&CD is utilized by either the Profile Control or the Gyrotron categories within the DIII-D PCS as dictated by the Off-Normal and Fault Response (ONFR) system, which monitors the occurrence of an NTM and regulates the authority over the gyrotrons. The total EC power and poloidal mirror angles are the gyrotron-related actuation variables. When no NTM suppression is required, the gyrotrons are used by the Profile Control category, but when NTM suppression is required, the ONFR transfers the authority over the gyrotrons to the NTM stabilization algorithm located in the Gyrotron category. Initial experimental results show that simultaneous control of different aspects of the plasma dynamics may improve the overall control and plasma performances. Also, the potential of the ONFR system to successfully integrate competing control algorithms is demonstrated.},
doi = {10.1016/j.fusengdes.2019.01.022},
journal = {Fusion Engineering and Design},
number = A,
volume = 146,
place = {United States},
year = {Sat Mar 16 00:00:00 EDT 2019},
month = {Sat Mar 16 00:00:00 EDT 2019}
}
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https://doi.org/10.1016/j.fusengdes.2019.01.022
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Works referenced in this record:

Implementing a finite-state off-normal and fault response system for disruption avoidance in tokamaks
journal, March 2018

Development, physics basis and performance projections for hybrid scenario operation in ITER on DIII-D
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  • DOI: 10.1063/1.1456066
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