Role of fast-ion transport manipulating safety factor profile in KSTAR early diverting discharges

J. Kang; T. Rhee; J. Kim; M. Podestà; L. Bardóczi; R. Nazikian; C. Z. Cheng; G. J. Kramer; M. J. Choi; S. H. Hahn; H. Han; M. H. Woo; H. Jhang; J. M. Park; J. M. Kwon

doi:10.1088/1741-4326/abb25b

Role of fast-ion transport manipulating safety factor profile in KSTAR early diverting discharges

J. Kang, T. Rhee, J. Kim, M. Podestà, L. Bardóczi, R. Nazikian, C. Z. Cheng, G. J. Kramer, M. J. Choi, S. H. Hahn, H. Han, M. H. Woo, H. Jhang, J. M. Park, J. M. Kwon

Plasma Theory and Modeling

Research output: Contribution to journal › Article › peer-review

10 Scopus citations

Abstract

Magnetohydrodynamics (MHD) activity is analyzed for a particular KSTAR discharge category, the main features of which are a high-q_min and a broad q profile. An interesting finding in this scenario is that a steady-state high-q_min and broad q profile has been constructed even without a strong off-axis current drive scheme. Time traces of magnetics spectrograms and electron cyclotron emission imaging (ECEI) clearly show that Alfvénic type MHD activity appears as a high-q_min and broad q profile is formed. Conversely, this activity disappears as the current profiles evolve toward a low-q_min profile. In this study, the effect of MHD modes and accompanying fast-particle transport on the formation of various current profiles is explored. The frequency patterns of the magnetics spectrograms and ECEI coherence are compared using a NOVA analysis to determine which series of Alfvénic modes are active. Then, the kick-model is applied to potential modes, and used to estimate how much fast-ions are transported and beam driven current profiles are varied. By comparing the reconstructed total current profile from the kinetic EFIT with the beam-driven current profile estimated from the kick model, it is determined how energetic particle transport is responsible for maintaining the safety factor profile and which q profile can provide high β_N operation.

Original language	English
Article number	126023
Journal	Nuclear Fusion
Volume	60
Issue number	12
DOIs	https://doi.org/10.1088/1741-4326/abb25b
State	Published - Dec 2020

Keywords

Alfvén eigenmode
Fast-ion transport
Kick-model
Q profile

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1088/1741-4326/abb25b

Cite this

Kang, J., Rhee, T., Kim, J., Podestà, M., Bardóczi, L., Nazikian, R., Cheng, C. Z., Kramer, G. J., Choi, M. J., Hahn, S. H., Han, H., Woo, M. H., Jhang, H., Park, J. M., & Kwon, J. M. (2020). Role of fast-ion transport manipulating safety factor profile in KSTAR early diverting discharges. Nuclear Fusion, 60(12), Article 126023. https://doi.org/10.1088/1741-4326/abb25b

@article{9651304f26994f6e8e191118cd2a3a2c,

title = "Role of fast-ion transport manipulating safety factor profile in KSTAR early diverting discharges",

abstract = "Magnetohydrodynamics (MHD) activity is analyzed for a particular KSTAR discharge category, the main features of which are a high-qmin and a broad q profile. An interesting finding in this scenario is that a steady-state high-qmin and broad q profile has been constructed even without a strong off-axis current drive scheme. Time traces of magnetics spectrograms and electron cyclotron emission imaging (ECEI) clearly show that Alfv{\'e}nic type MHD activity appears as a high-qmin and broad q profile is formed. Conversely, this activity disappears as the current profiles evolve toward a low-qmin profile. In this study, the effect of MHD modes and accompanying fast-particle transport on the formation of various current profiles is explored. The frequency patterns of the magnetics spectrograms and ECEI coherence are compared using a NOVA analysis to determine which series of Alfv{\'e}nic modes are active. Then, the kick-model is applied to potential modes, and used to estimate how much fast-ions are transported and beam driven current profiles are varied. By comparing the reconstructed total current profile from the kinetic EFIT with the beam-driven current profile estimated from the kick model, it is determined how energetic particle transport is responsible for maintaining the safety factor profile and which q profile can provide high βN operation.",

keywords = "Alfv{\'e}n eigenmode, Fast-ion transport, Kick-model, Q profile",

author = "J. Kang and T. Rhee and J. Kim and M. Podest{\`a} and L. Bard{\'o}czi and R. Nazikian and Cheng, {C. Z.} and Kramer, {G. J.} and Choi, {M. J.} and Hahn, {S. H.} and H. Han and Woo, {M. H.} and H. Jhang and Park, {J. M.} and Kwon, {J. M.}",

note = "Publisher Copyright: {\textcopyright} 2020 IAEA, Vienna Printed in the UK",

year = "2020",

month = dec,

doi = "10.1088/1741-4326/abb25b",

language = "English",

volume = "60",

journal = "Nuclear Fusion",

issn = "0029-5515",

publisher = "IOP Publishing",

number = "12",

}

TY - JOUR

T1 - Role of fast-ion transport manipulating safety factor profile in KSTAR early diverting discharges

AU - Kang, J.

AU - Rhee, T.

AU - Kim, J.

AU - Podestà, M.

AU - Bardóczi, L.

AU - Nazikian, R.

AU - Cheng, C. Z.

AU - Kramer, G. J.

AU - Choi, M. J.

AU - Hahn, S. H.

AU - Han, H.

AU - Woo, M. H.

AU - Jhang, H.

AU - Park, J. M.

AU - Kwon, J. M.

PY - 2020/12

Y1 - 2020/12

N2 - Magnetohydrodynamics (MHD) activity is analyzed for a particular KSTAR discharge category, the main features of which are a high-qmin and a broad q profile. An interesting finding in this scenario is that a steady-state high-qmin and broad q profile has been constructed even without a strong off-axis current drive scheme. Time traces of magnetics spectrograms and electron cyclotron emission imaging (ECEI) clearly show that Alfvénic type MHD activity appears as a high-qmin and broad q profile is formed. Conversely, this activity disappears as the current profiles evolve toward a low-qmin profile. In this study, the effect of MHD modes and accompanying fast-particle transport on the formation of various current profiles is explored. The frequency patterns of the magnetics spectrograms and ECEI coherence are compared using a NOVA analysis to determine which series of Alfvénic modes are active. Then, the kick-model is applied to potential modes, and used to estimate how much fast-ions are transported and beam driven current profiles are varied. By comparing the reconstructed total current profile from the kinetic EFIT with the beam-driven current profile estimated from the kick model, it is determined how energetic particle transport is responsible for maintaining the safety factor profile and which q profile can provide high βN operation.

AB - Magnetohydrodynamics (MHD) activity is analyzed for a particular KSTAR discharge category, the main features of which are a high-qmin and a broad q profile. An interesting finding in this scenario is that a steady-state high-qmin and broad q profile has been constructed even without a strong off-axis current drive scheme. Time traces of magnetics spectrograms and electron cyclotron emission imaging (ECEI) clearly show that Alfvénic type MHD activity appears as a high-qmin and broad q profile is formed. Conversely, this activity disappears as the current profiles evolve toward a low-qmin profile. In this study, the effect of MHD modes and accompanying fast-particle transport on the formation of various current profiles is explored. The frequency patterns of the magnetics spectrograms and ECEI coherence are compared using a NOVA analysis to determine which series of Alfvénic modes are active. Then, the kick-model is applied to potential modes, and used to estimate how much fast-ions are transported and beam driven current profiles are varied. By comparing the reconstructed total current profile from the kinetic EFIT with the beam-driven current profile estimated from the kick model, it is determined how energetic particle transport is responsible for maintaining the safety factor profile and which q profile can provide high βN operation.

KW - Alfvén eigenmode

KW - Fast-ion transport

KW - Kick-model

KW - Q profile

UR - http://www.scopus.com/inward/record.url?scp=85095863501&partnerID=8YFLogxK

U2 - 10.1088/1741-4326/abb25b

DO - 10.1088/1741-4326/abb25b

M3 - Article

AN - SCOPUS:85095863501

SN - 0029-5515

VL - 60

JO - Nuclear Fusion

JF - Nuclear Fusion

IS - 12

M1 - 126023

ER -

Role of fast-ion transport manipulating safety factor profile in KSTAR early diverting discharges

Abstract

Keywords

UN SDGs

Access to Document

Other files and links

Fingerprint

Cite this