Development and experimental qualification of novel disruption prevention techniques on DIII-D

Barr, Jayson L.; Sammuli, Brian S.; Humphreys, Dave A.; Olofsson, K. Eric J.; Du, Xiaodi; Rea, Cristina; Wehner, Will P.; Boyer, Mark D.; Eidietis, Nicholas W.; Granetz, Robert; Hyatt, A. W.; Liu, Tong; Logan, Nikolas; Munaretto, Stefano; Strait, E. J.; Wang, Zhirui

doi:10.1088/1741-4326/ac2d56

Title: Development and experimental qualification of novel disruption prevention techniques on DIII-D

Abstract

Novel disruption prevention solutions spanning a range of control regimes are being developed and tested on DIII-D to enable ITER success. First, a new real-time control algorithm has been developed and tested for regulating nearness to stability limits and maintaining safety-margins. Its first application has been for reliable prevention of vertical displacement events (VDEs) by adjusting plasma elongation (κ) and the inner-gap between the plasma and inner-wall in response to real- time open-loop VDE growth rate (γ) estimators. VDEs were robustly prevented up to average open-loop growth rates of 800 rad/s with initial tunings, with only applying shape modification when near safety limits. Second, the disruption risk during fast, emergency shutdown after large tearing and locked modes can be significantly improved by transitioning to a limited topology during shutdown. More than 50% of emergency limited shutdowns after locked modes reach a final normalized current I_N < 0.3 before terminating, scaling to the 3 MA ITER requirement. Furthermore, this is in contrast to diverted shutdowns, the majority of which disrupt at I_N > 0.8. Despite improvements, these results highlight the critical importance of early prevention. Third, a novel emergency shut down method has been developed which excites instabilities to form amore »« less

Authors:

^[1]; Sammuli, Brian S. ^[1]; Humphreys, Dave A. ^[1];

^[1];

^[2]; Wehner, Will P. ^[1];

^[3];

^[1]; Granetz, Robert ^[2]; Hyatt, A. W. ^[1];

^[4];

^[5]; Munaretto, Stefano ^[1];

^[1];

^[3]

General Atomics, San Diego, CA (United States)
Massachusetts Inst. of Technology Plasma Science and Fusion Center, Cambridge, MA (United States)
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Dalian Univ. of Technology (China)
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Publication Date:: Wed Oct 06 00:00:00 EDT 2021

Research Org.:: General Atomics, San Diego, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Org.:: USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:: 1826166

Alternate Identifier(s):: OSTI ID: 1836940

Report Number(s):: LLNL-JRNL-828737
Journal ID: ISSN 0029-5515; TRN: US2215874

Grant/Contract Number:: FC02-04ER54698; AC02-09CH11466; AC52-07NA27344; SC0014264

Resource Type:: Accepted Manuscript

Journal Name:: Nuclear Fusion

Additional Journal Information:: Journal Volume: 61; Journal Issue: 12; Journal ID: ISSN 0029-5515

Publisher:: IOP Science

Country of Publication:: United States

Language:: English

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; tokamak stability; disruption prevention; plasma control; Physics - Plasma physics

Citation Formats


                    Barr, Jayson L., Sammuli, Brian S., Humphreys, Dave A., Olofsson, K. Eric J., Du, Xiaodi, Rea, Cristina, Wehner, Will P., Boyer, Mark D., Eidietis, Nicholas W., Granetz, Robert, Hyatt, A. W., Liu, Tong, Logan, Nikolas, Munaretto, Stefano, Strait, E. J., and Wang, Zhirui. Development and experimental qualification of novel disruption prevention techniques on DIII-D.  United States: N. p., 2021. 
Web.  doi:10.1088/1741-4326/ac2d56.

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                    Barr, Jayson L., Sammuli, Brian S., Humphreys, Dave A., Olofsson, K. Eric J., Du, Xiaodi, Rea, Cristina, Wehner, Will P., Boyer, Mark D., Eidietis, Nicholas W., Granetz, Robert, Hyatt, A. W., Liu, Tong, Logan, Nikolas, Munaretto, Stefano, Strait, E. J., & Wang, Zhirui. Development and experimental qualification of novel disruption prevention techniques on DIII-D.  United States.  https://doi.org/10.1088/1741-4326/ac2d56

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                    Barr, Jayson L., Sammuli, Brian S., Humphreys, Dave A., Olofsson, K. Eric J., Du, Xiaodi, Rea, Cristina, Wehner, Will P., Boyer, Mark D., Eidietis, Nicholas W., Granetz, Robert, Hyatt, A. W., Liu, Tong, Logan, Nikolas, Munaretto, Stefano, Strait, E. J., and Wang, Zhirui. Wed .  
"Development and experimental qualification of novel disruption prevention techniques on DIII-D".  United States.  https://doi.org/10.1088/1741-4326/ac2d56.  https://www.osti.gov/servlets/purl/1826166.

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@article{osti_1826166,

  title        = {Development and experimental qualification of novel disruption prevention techniques on DIII-D},

  author       = {Barr, Jayson L. and Sammuli, Brian S. and Humphreys, Dave A. and Olofsson, K. Eric J. and Du, Xiaodi and Rea, Cristina and Wehner, Will P. and Boyer, Mark D. and Eidietis, Nicholas W. and Granetz, Robert and Hyatt, A. W. and Liu, Tong and Logan, Nikolas and Munaretto, Stefano and Strait, E. J. and Wang, Zhirui},

  abstractNote = {Novel disruption prevention solutions spanning a range of control regimes are being developed and tested on DIII-D to enable ITER success. First, a new real-time control algorithm has been developed and tested for regulating nearness to stability limits and maintaining safety-margins. Its first application has been for reliable prevention of vertical displacement events (VDEs) by adjusting plasma elongation (κ) and the inner-gap between the plasma and inner-wall in response to real- time open-loop VDE growth rate (γ) estimators. VDEs were robustly prevented up to average open-loop growth rates of 800 rad/s with initial tunings, with only applying shape modification when near safety limits. Second, the disruption risk during fast, emergency shutdown after large tearing and locked modes can be significantly improved by transitioning to a limited topology during shutdown. More than 50% of emergency limited shutdowns after locked modes reach a final normalized current I_N < 0.3 before terminating, scaling to the 3 MA ITER requirement. Furthermore, this is in contrast to diverted shutdowns, the majority of which disrupt at I_N > 0.8. Despite improvements, these results highlight the critical importance of early prevention. Third, a novel emergency shut down method has been developed which excites instabilities to form a warm, helical core post-thermal quench. The current quench extends to ~100ms and avoids VDEs and runaway electron generation. Novel real-time machine learning disruption prediction has been integrated with the DIII-D proximity controller, and a real- time compatible multi-mode MHD spectroscopy technique has been developed. Results presented here were enabled by a focused effort, the Disruption Free Protocol, in DIII-D’s 2019-20 campaign to complement disruption prevention experiments with a large piggy-back program. In addition to testing novel techniques, it is estimated to have helped avoid 32 potential disruptions in piggyback operations with rapid, early shutdowns after large rotating n=1 or locked modes.},

  doi          = {10.1088/1741-4326/ac2d56},

  journal      = {Nuclear Fusion},

  number       = 12,

  volume       = 61,

  place        = {United States},

  year         = {Wed Oct 06 00:00:00 EDT 2021},

  month        = {Wed Oct 06 00:00:00 EDT 2021}

}

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Similar Records

Title: Development and experimental qualification of novel disruption prevention techniques on DIII-D

Abstract

Citation Formats

A real-time machine learning-based disruption predictor in DIII-D journal, July 2019

Statistical analysis of disruptions in JET journal, April 2009

Feedback control of the proximity to marginal RWM stability using active MHD spectroscopy journal, November 2011

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First observation of plasma healing via helical equilibrium in tokamak disruptions journal, July 2019

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