First access to ELM-free negative triangularity at low aspect ratio

Nelson, A. O.; Vincent, C.; Anand, H.; Lovell, J.; Parisi, J. F.; Wilson, H. S.; Imada, K.; Wehner, W. P.; Kochan, M.; Blackmore, S.; McArdle, G.; Guizzo, S.; Rondini, L.; Freiberger, S.; Paz-Soldan, C.

doi:10.1088/1741-4326/ad89db

Title: First access to ELM-free negative triangularity at low aspect ratio

Journal Article · 28 October 2024 · Nuclear Fusion

DOI: https://doi.org/10.1088/1741-4326/ad89db · OSTI ID:2475207

^[1]; Vincent, C. ^[2]; Anand, H. ^[3];

^[4];

^[5];

^[1];

^[6]; Wehner, W. P. ^[3]; Kochan, M. ^[2]; Blackmore, S. ^[2];

^[2];

^[1]; Rondini, L. ^[1]; Freiberger, S. ^[1];

^[1]

Columbia University, New York, NY (United States)
UKAEA-CCFE, Oxon (United Kingdom of Great Britain and Northern Ireland)
General Atomics, San Diego, CA (United States)
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
York Plasma Institute (United Kingdom of Great Britain and Northern Ireland)

A plasma scenario with negative triangularity (NT) shaping is achieved on MAST-U for the first time. While edge localized modes (ELMs) are eventually suppressed as the triangularity is decreased below δ ≲ –0.06, an extended period of H-mode operation with Type-III ELMs is sustained at less negative δ even through access to the second stability region for ideal ballooning modes is closed. This documents a qualitative difference from the ELM-free access conditions documented in NT scenarios on conventional aspect ratio machines. The electron temperature at the pedestal top drops across the transition to ELM-free operation, but a steady rise in core temperature as δ is decreased allows for similar normalized β in the ELM-free NT and H-mode positive triangularity shapes.

View Journal Article

Cite

Export

Save

Research Organization:: Columbia University, New York, NY (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: USDOE; USDOE Office of Science (SC); USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Contributing Organization:: The MAST-U Team

Grant/Contract Number:: AC05-00OR22725; FC02-04ER54698; SC0018991; SC0022272

OSTI ID:: 2475207

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 12 Vol. 64; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

References (48)

A brief history of negative triangularity tokamak plasmas Marinoni, A.; Sauter, O.; Coda, S. Reviews of Modern Plasma Physics, Vol. 5, Issue 1 https://doi.org/10.1007/s41614-021-00054-0	journal	October 2021
The CHEASE code for toroidal MHD equilibria Lütjens, H.; Bondeson, A.; Sauter, O. Computer Physics Communications, Vol. 97, Issue 3 https://doi.org/10.1016/0010-4655(96)00046-X	journal	September 1996
TokaMaker: An open-source time-dependent Grad-Shafranov tool for the design and modeling of axisymmetric fusion devices Hansen, C.; Stewart, I. G.; Burgess, D. Computer Physics Communications, Vol. 298 https://doi.org/10.1016/j.cpc.2024.109111	journal	May 2024
The MAST Upgrade plasma control system McArdle, Graham; Pangione, Luigi; Kochan, Martin Fusion Engineering and Design, Vol. 159 https://doi.org/10.1016/j.fusengdes.2020.111764	journal	October 2020
Mechanical and electromagnetic design of the vacuum vessel of the SMART tokamak Mancini, A.; Ayllon-Guerola, J.; Doyle, S. J. Fusion Engineering and Design, Vol. 171 https://doi.org/10.1016/j.fusengdes.2021.112542	journal	October 2021
Magnetic equilibrium design for the SMART tokamak Doyle, S. J.; Lopez-Aires, D.; Mancini, A. Fusion Engineering and Design, Vol. 171 https://doi.org/10.1016/j.fusengdes.2021.112706	journal	October 2021
Edge localized modes and the pedestal: A model based on coupled peeling–ballooning modes Snyder, P. B.; Wilson, H. R.; Ferron, J. R. Physics of Plasmas, Vol. 9, Issue 5 https://doi.org/10.1063/1.1449463	journal	May 2002
A theory-based transport model with comprehensive physics Staebler, G. M.; Kinsey, J. E.; Waltz, R. E. Physics of Plasmas, Vol. 14, Issue 5 https://doi.org/10.1063/1.2436852	journal	May 2007
On the non-stiffness of edge transport in L-mode tokamak plasmas Sauter, O.; Brunner, S.; Kim, D. Physics of Plasmas, Vol. 21, Issue 5 https://doi.org/10.1063/1.4876612	journal	May 2014
Effect of resistivity on small edge localized mode Wu, N.; Chen, S. Y.; Mou, M. L. Physics of Plasmas, Vol. 25, Issue 9 https://doi.org/10.1063/1.5038042	journal	September 2018
Stable equilibria for bootstrap-current-driven low aspect ratio tokamaks Miller, R. L.; Lin-Liu, Y. R.; Turnbull, A. D. Physics of Plasmas, Vol. 4, Issue 4 https://doi.org/10.1063/1.872193	journal	April 1997
A new set of analytical formulae for the computation of the bootstrap current and the neoclassical conductivity in tokamaks Redl, A.; Angioni, C.; Belli, E. Physics of Plasmas, Vol. 28, Issue 2 https://doi.org/10.1063/5.0012664	journal	February 2021
Different roles of elongation and triangularity in the H-mode pedestal height enhancement through strong plasma shaping Kim, J. Y.; Han, H. S.; Kim, S. K. Physics of Plasmas, Vol. 29, Issue 11 https://doi.org/10.1063/5.0124745	journal	November 2022
Understanding the negative triangularity ELM trigger and ELM free state on DIII-D with ECE-imaging Yu, G.; Li, Z.; Kramer, G. Physics of Plasmas, Vol. 30, Issue 6 https://doi.org/10.1063/5.0144711	journal	June 2023
Flexible, integrated modeling of tokamak stability, transport, equilibrium, and pedestal physics Lyons, B. C.; McClenaghan, J.; Slendebroek, T. Physics of Plasmas, Vol. 30, Issue 9 https://doi.org/10.1063/5.0156877	journal	September 2023
Kinetic-ballooning-bifurcation in tokamak pedestals across shaping and aspect-ratio Parisi, J. F.; Nelson, A. O.; Gaur, R. Physics of Plasmas, Vol. 31, Issue 3 https://doi.org/10.1063/5.0190818	journal	March 2024
Reconstruction of current profile parameters and plasma shapes in tokamaks Lao, L. L.; St. John, H.; Stambaugh, R. D. Nuclear Fusion, Vol. 25, Issue 11 https://doi.org/10.1088/0029-5515/25/11/007	journal	November 1985
Stability of localized MHD modes in divertor tokamaks – a picture of the H-mode Bishop, C. M. Nuclear Fusion, Vol. 26, Issue 8 https://doi.org/10.1088/0029-5515/26/8/006	journal	August 1986
Transition to the second region of ideal MHD stability Sabbagh, S. A.; Hughes, M. H.; Phillips, M. W. Nuclear Fusion, Vol. 29, Issue 3 https://doi.org/10.1088/0029-5515/29/3/006	journal	March 1989
Impact of plasma triangularity and collisionality on electron heat transport in TCV L-mode plasmas Camenen, Y.; Pochelon, A.; Behn, R. Nuclear Fusion, Vol. 47, Issue 7 https://doi.org/10.1088/0029-5515/47/7/002	journal	June 2007
Development of ITER-relevant plasma control solutions at DIII-D Humphreys, D. A.; Ferron, J. R.; Bakhtiari, M. Nuclear Fusion, Vol. 47, Issue 8 https://doi.org/10.1088/0029-5515/47/8/028	journal	July 2007
Overview of the physics and engineering design of NSTX upgrade Menard, J. E.; Gerhardt, S.; Bell, M. Nuclear Fusion, Vol. 52, Issue 8 https://doi.org/10.1088/0029-5515/52/8/083015	journal	July 2012
The negative triangularity tokamak: stability limits and prospects as a fusion energy system Medvedev, S. Yu.; Kikuchi, M.; Villard, L. Nuclear Fusion, Vol. 55, Issue 6 https://doi.org/10.1088/0029-5515/55/6/063013	journal	May 2015
Integrated modeling applications for tokamak experiments with OMFIT Meneghini, O.; Smith, S. P.; Lao, L. L. Nuclear Fusion, Vol. 55, Issue 8 https://doi.org/10.1088/0029-5515/55/8/083008	journal	July 2015
Edge localized modes (ELMs) Zohm, H. Plasma Physics and Controlled Fusion, Vol. 38, Issue 2 https://doi.org/10.1088/0741-3335/38/2/001	journal	February 1996
Edge-localized modes - physics and theory Connor, J. W. Plasma Physics and Controlled Fusion, Vol. 40, Issue 5 https://doi.org/10.1088/0741-3335/40/5/002	journal	May 1998
The physics of large and small edge localized modes Suttrop, W. Plasma Physics and Controlled Fusion, Vol. 42, Issue 5A https://doi.org/10.1088/0741-3335/42/5A/301	journal	May 2000
Towards the construction of a model to describe the inter-ELM evolution of the pedestal on MAST Dickinson, D.; Saarelma, S.; Scannell, R. Plasma Physics and Controlled Fusion, Vol. 53, Issue 11 https://doi.org/10.1088/0741-3335/53/11/115010	journal	October 2011
Pedestal properties of H-modes with negative triangularity using the EPED-CH model Merle, A.; Sauter, O.; Medvedev, S. Yu Plasma Physics and Controlled Fusion, Vol. 59, Issue 10 https://doi.org/10.1088/1361-6587/aa7ac0	journal	August 2017
Ballooning instability preventing the H-mode access in plasmas with negative triangularity shape on the DIII–D tokamak Saarelma, S.; Austin, M. E.; Knolker, M. Plasma Physics and Controlled Fusion, Vol. 63, Issue 10 https://doi.org/10.1088/1361-6587/ac1ea4	journal	September 2021
Enhanced confinement in diverted negative-triangularity L-mode plasmas in TCV Coda, S.; Merle, A.; Sauter, O. Plasma Physics and Controlled Fusion, Vol. 64, Issue 1 https://doi.org/10.1088/1361-6587/ac3fec	journal	December 2021
Kinetic ballooning modes as a constraint on plasma triangularity in commercial spherical tokamaks Davies, R.; Dickinson, D.; Wilson, H. Plasma Physics and Controlled Fusion, Vol. 64, Issue 10 https://doi.org/10.1088/1361-6587/ac8615	journal	August 2022
Optimization of the N∥ Upshift in the DIII-D high field side lower hybrid current drive experiment Rutherford, Grant; Frank, Samuel J.; Seltzman, Andrew H. Plasma Physics and Controlled Fusion, Vol. 66, Issue 6 https://doi.org/10.1088/1361-6587/ad44d6	journal	May 2024
Physical insights from the aspect ratio dependence of turbulence in negative triangularity plasmas Balestri, A.; Ball, J.; Coda, S. Plasma Physics and Controlled Fusion, Vol. 66, Issue 7 https://doi.org/10.1088/1361-6587/ad4d1d	journal	May 2024
Characterization of the ELM-free negative triangularity edge on DIII-D Nelson, A. O.; Schmitz, L.; Cote, T. Plasma Physics and Controlled Fusion, Vol. 66, Issue 10 https://doi.org/10.1088/1361-6587/ad6a83	journal	September 2024
Power handling in a highly-radiative negative triangularity pilot plant Miller, M. A.; Arnold, D.; Wigram, M. Plasma Physics and Controlled Fusion, Vol. 66, Issue 12 https://doi.org/10.1088/1361-6587/ad867a	journal	October 2024
Effect of negative triangularity on peeling-ballooning instability Qin, Chenchen; Mou, Maolin; Chen, Shaoyong Physica Scripta, Vol. 98, Issue 4 https://doi.org/10.1088/1402-4896/acbdcb	journal	March 2023
L-mode-edge negative triangularity tokamak reactor Kikuchi, M.; Takizuka, T.; Medvedev, S. Nuclear Fusion, Vol. 59, Issue 5 https://doi.org/10.1088/1741-4326/ab076d	journal	April 2019
Prospects for H-mode inhibition in negative triangularity tokamak reactor plasmas Nelson, A. O.; Paz-Soldan, C.; Saarelma, S. Nuclear Fusion, Vol. 62, Issue 9 https://doi.org/10.1088/1741-4326/ac8064	journal	August 2022
Kinetic-ballooning-limited pedestals in spherical tokamak plasmas Parisi, J. F.; Guttenfelder, W.; Nelson, A. O. Nuclear Fusion, Vol. 64, Issue 5 https://doi.org/10.1088/1741-4326/ad39fb	journal	April 2024
Stability and transport of gyrokinetic critical pedestals Parisi, J. F.; Nelson, A. O.; Guttenfelder, W. Nuclear Fusion, Vol. 64, Issue 8 https://doi.org/10.1088/1741-4326/ad4d02	journal	June 2024
Real-time plasma equilibrium reconstruction and shape control for the MAST Upgrade tokamak Anand, H.; Wehner, W.; Eldon, D. Nuclear Fusion, Vol. 64, Issue 8 https://doi.org/10.1088/1741-4326/ad5c80	journal	July 2024
Simultaneous access to high normalized density, current, pressure, and confinement in strongly-shaped diverted negative triangularity plasmas Paz-Soldan, C.; Chrystal, C.; Lunia, P. Nuclear Fusion, Vol. 64, Issue 9 https://doi.org/10.1088/1741-4326/ad69a4 094002	journal	August 2024
Power requirement for accessing the H-mode in ITER Martin, Y. R.; Takizuka, T.; Group, the ITPA CDBM H-mode Threshold Data Journal of Physics: Conference Series, Vol. 123 https://doi.org/10.1088/1742-6596/123/1/012033	journal	July 2008
Achievement of Reactor-Relevant Performance in Negative Triangularity Shape in the DIII-D Tokamak Austin, M. E.; Marinoni, A.; Walker, M. L. Physical Review Letters, Vol. 122, Issue 11 https://doi.org/10.1103/PhysRevLett.122.115001	journal	March 2019
Robust Avoidance of Edge-Localized Modes alongside Gradient Formation in the Negative Triangularity Tokamak Edge Nelson, A. O.; Schmitz, L.; Paz-Soldan, C. Physical Review Letters, Vol. 131, Issue 19 https://doi.org/10.1103/PhysRevLett.131.195101	journal	November 2023
Transp Breslau, Joshua; Gorelenkova, Marina; Poli, Francesca Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States) https://doi.org/10.11578/dc.20180627.4	software	June 2018
Multichannel grazing-incidence spectrometer for plasma impurity diagnosis: SPRED Fonck, R. J.; Ramsey, A. T.; Yelle, R. V. Applied Optics, Vol. 21, Issue 12 https://doi.org/10.1364/AO.21.002115	journal	January 1982

Similar Records

Characterization of the ELM-free negative triangularity edge on DIII-D

Journal Article · 2024 · Plasma Physics and Controlled Fusion · OSTI ID:2440719

Nelson, A. O.; Schmitz, L.; Cote, T.; +18 more

Prospects for H-mode inhibition in negative triangularity tokamak reactor plasmas

Journal Article · 2022 · Nuclear Fusion · OSTI ID:1903630

Nelson, A. O.; Paz-Soldan, C.; Saarelma, S.

Ballooning instability preventing the H-mode access in plasmas with negative triangularity shape on the DIII-D tokamak

Journal Article · 2021 · Plasma Physics and Controlled Fusion · OSTI ID:1818123

Saarelma, Samuli; Austin, Max E.; Knölker, M.; +4 more

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ELM-free
MAST-U
negative triangularity
tokamak

Title: First access to ELM-free negative triangularity at low aspect ratio

Citation Formats

References (48)

Similar Records

Related Subjects