Analysis of the ECH effect on EPM/AE stability in Heliotron J plasma using a Landau closure model

J. Varela; K. Nagasaki; S. Kobayashi; K. Nagaoka; P. Adulsiriswad; A. Cappa; S. Yamamoto; K. Y. Watanabe; D. A. Spong; L. Garcia; Y. Ghai; J. Ortiz

doi:10.1088/1741-4326/aca98e

Analysis of the ECH effect on EPM/AE stability in Heliotron J plasma using a Landau closure model

J. Varela, K. Nagasaki, S. Kobayashi, K. Nagaoka, P. Adulsiriswad, A. Cappa, S. Yamamoto, K. Y. Watanabe, D. A. Spong, L. Garcia, Y. Ghai, J. Ortiz

Plasma Theory and Modeling

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4 Scopus citations

Abstract

The aim of the present study is to analyze the effect of the electron cyclotron heating (ECH) on the linear stability of Alfvén eigenmodes (AEs) and energetic particle modes (EPMs) triggered by energetic ions in Heliotron J plasma. The analysis is performed using the FAR3d code that solves a reduced MHD model to describe the thermal plasma coupled with a gyrofluid model for the energetic particle (EP) species. The simulations reproduce the AE/EPM stability trends observed in the experiments as the electron temperature (Te) increases, modifying the thermal plasma β, EP β and EP slowing-down time. Particularly, the n/m = 1/2 EPM and 2/4 Global AE are stabilized in the low-bumpiness (LB) configuration due to an enhancement of the continuum, finite Larmor radius and e-i Landau damping effects as the thermal β increases. On the other hand, a larger ECH injection power cannot stabilize the AE/EPM in medium-bumpiness and high-bumpiness (HB) configurations because the damping effects are weaker compared to the LB case, unable to balance the further destabilization induced by an enhanced EP resonance as the EP slowing-down time and EP β increases with Te.

Original language	English
Article number	026009
Journal	Nuclear Fusion
Volume	63
Issue number	2
DOIs	https://doi.org/10.1088/1741-4326/aca98e
State	Published - Feb 2023

Funding

The authors would like to thank the Heliotron J technical staff for their contributions in the operation and maintenance of Heliotron J. This work was supported by the Comunidad de Madrid under the Project 2019-T1/AMB-13648, Comunidad de Madrid—multiannual agreement with UC3M (‘Excelen-cia para el Profesorado Universitario’—EPUC3M14 )—Fifth regional research plan 2016–2020 as well as NIFS Collaborative Research Program NIFS08KAOR010, NFIS10KUHL030, NIFS07KLPH004 and ‘PLADyS’ JSPS Core-to-Core Program, A. Advanced Research Networks.

Keywords

AE
ECH
EPM
Heliotron J
MHD
energetic particles
stellarator

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title = "Analysis of the ECH effect on EPM/AE stability in Heliotron J plasma using a Landau closure model",

abstract = "The aim of the present study is to analyze the effect of the electron cyclotron heating (ECH) on the linear stability of Alfv{\'e}n eigenmodes (AEs) and energetic particle modes (EPMs) triggered by energetic ions in Heliotron J plasma. The analysis is performed using the FAR3d code that solves a reduced MHD model to describe the thermal plasma coupled with a gyrofluid model for the energetic particle (EP) species. The simulations reproduce the AE/EPM stability trends observed in the experiments as the electron temperature (Te) increases, modifying the thermal plasma β, EP β and EP slowing-down time. Particularly, the n/m = 1/2 EPM and 2/4 Global AE are stabilized in the low-bumpiness (LB) configuration due to an enhancement of the continuum, finite Larmor radius and e-i Landau damping effects as the thermal β increases. On the other hand, a larger ECH injection power cannot stabilize the AE/EPM in medium-bumpiness and high-bumpiness (HB) configurations because the damping effects are weaker compared to the LB case, unable to balance the further destabilization induced by an enhanced EP resonance as the EP slowing-down time and EP β increases with Te.",

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author = "J. Varela and K. Nagasaki and S. Kobayashi and K. Nagaoka and P. Adulsiriswad and A. Cappa and S. Yamamoto and Watanabe, {K. Y.} and Spong, {D. A.} and L. Garcia and Y. Ghai and J. Ortiz",

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AU - Varela, J.

AU - Nagasaki, K.

AU - Kobayashi, S.

AU - Nagaoka, K.

AU - Adulsiriswad, P.

AU - Cappa, A.

AU - Yamamoto, S.

AU - Watanabe, K. Y.

AU - Spong, D. A.

AU - Garcia, L.

AU - Ghai, Y.

AU - Ortiz, J.

PY - 2023/2

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N2 - The aim of the present study is to analyze the effect of the electron cyclotron heating (ECH) on the linear stability of Alfvén eigenmodes (AEs) and energetic particle modes (EPMs) triggered by energetic ions in Heliotron J plasma. The analysis is performed using the FAR3d code that solves a reduced MHD model to describe the thermal plasma coupled with a gyrofluid model for the energetic particle (EP) species. The simulations reproduce the AE/EPM stability trends observed in the experiments as the electron temperature (Te) increases, modifying the thermal plasma β, EP β and EP slowing-down time. Particularly, the n/m = 1/2 EPM and 2/4 Global AE are stabilized in the low-bumpiness (LB) configuration due to an enhancement of the continuum, finite Larmor radius and e-i Landau damping effects as the thermal β increases. On the other hand, a larger ECH injection power cannot stabilize the AE/EPM in medium-bumpiness and high-bumpiness (HB) configurations because the damping effects are weaker compared to the LB case, unable to balance the further destabilization induced by an enhanced EP resonance as the EP slowing-down time and EP β increases with Te.

AB - The aim of the present study is to analyze the effect of the electron cyclotron heating (ECH) on the linear stability of Alfvén eigenmodes (AEs) and energetic particle modes (EPMs) triggered by energetic ions in Heliotron J plasma. The analysis is performed using the FAR3d code that solves a reduced MHD model to describe the thermal plasma coupled with a gyrofluid model for the energetic particle (EP) species. The simulations reproduce the AE/EPM stability trends observed in the experiments as the electron temperature (Te) increases, modifying the thermal plasma β, EP β and EP slowing-down time. Particularly, the n/m = 1/2 EPM and 2/4 Global AE are stabilized in the low-bumpiness (LB) configuration due to an enhancement of the continuum, finite Larmor radius and e-i Landau damping effects as the thermal β increases. On the other hand, a larger ECH injection power cannot stabilize the AE/EPM in medium-bumpiness and high-bumpiness (HB) configurations because the damping effects are weaker compared to the LB case, unable to balance the further destabilization induced by an enhanced EP resonance as the EP slowing-down time and EP β increases with Te.

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Analysis of the ECH effect on EPM/AE stability in Heliotron J plasma using a Landau closure model

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