Control of core argon impurity profile by ECH in KSTAR L-mode plasmas

Joohwan Hong, Seung Hun Lee, Juhyung Kim, C.R. Seon, S.G. Lee, G.Y. Park, K.D. Lee, S.S. Henderson, H.Y. Lee, Jae Sun Park, Juhyeok Jang, Siwon Jang, Taemin Jeon, M. O'Mullane, Wonhoe Choe

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Experiments on trace argon impurity transport in L-mode discharges were performed on Korea superconducting tokamak advanced research (KSTAR) with electron cyclotron resonance heating (ECH). Ar emission was measured by soft x-ray (SXR) arrays and vacuum UV (VUV) diagnostics. A significant reduction in the core Ar emissivity was observed with core ECH. The reduction was the largest with on-axis heating and became smaller with outward heating positions. The diffusivity and convection velocity of Ar were obtained by analysis of the SXR data with the SANCO impurity transport code for the on-axis ECH and the non-ECH shots. In the on-axis ECH case, both diffusivity and convection velocity increased. Furthermore, the convection changed its direction from inward to outward in the plasma core (r/a?<?0.3), resulting in a hollow profile of the total Ar density. Together with the reduction in the SXR signals, the hollow impurity profile in the core and the reversal of the convection velocity consistently confirm that ECH can reduce impurity accumulation in the core region. Neoclassical impurity transport and linear stability of micro-turbulence were calculated and discussed in relation to the possible transport mechanism.
LanguageEnglish
Article number063016
Number of pages9
JournalNuclear Fusion
Volume55
Issue number6
DOIs
Publication statusPublished - 6 May 2015

Fingerprint

Korea
electron cyclotron resonance
argon
impurities
heating
profiles
convection
diffusivity
hollow
x rays
cyclotron resonance
emissivity
shot
turbulence
vacuum

Keywords

  • plasma impurities
  • soft X-ray
  • tokamaks
  • gamma ray measurement

Cite this

Hong, J., Lee, S. H., Kim, J., Seon, C. R., Lee, S. G., Park, G. Y., ... Choe, W. (2015). Control of core argon impurity profile by ECH in KSTAR L-mode plasmas. Nuclear Fusion, 55(6), [063016]. https://doi.org/10.1088/0029-5515/55/6/063016
Hong, Joohwan ; Lee, Seung Hun ; Kim, Juhyung ; Seon, C.R. ; Lee, S.G. ; Park, G.Y. ; Lee, K.D. ; Henderson, S.S. ; Lee, H.Y. ; Park, Jae Sun ; Jang, Juhyeok ; Jang, Siwon ; Jeon, Taemin ; O'Mullane, M. ; Choe, Wonhoe. / Control of core argon impurity profile by ECH in KSTAR L-mode plasmas. In: Nuclear Fusion. 2015 ; Vol. 55, No. 6.
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abstract = "Experiments on trace argon impurity transport in L-mode discharges were performed on Korea superconducting tokamak advanced research (KSTAR) with electron cyclotron resonance heating (ECH). Ar emission was measured by soft x-ray (SXR) arrays and vacuum UV (VUV) diagnostics. A significant reduction in the core Ar emissivity was observed with core ECH. The reduction was the largest with on-axis heating and became smaller with outward heating positions. The diffusivity and convection velocity of Ar were obtained by analysis of the SXR data with the SANCO impurity transport code for the on-axis ECH and the non-ECH shots. In the on-axis ECH case, both diffusivity and convection velocity increased. Furthermore, the convection changed its direction from inward to outward in the plasma core (r/a?<?0.3), resulting in a hollow profile of the total Ar density. Together with the reduction in the SXR signals, the hollow impurity profile in the core and the reversal of the convection velocity consistently confirm that ECH can reduce impurity accumulation in the core region. Neoclassical impurity transport and linear stability of micro-turbulence were calculated and discussed in relation to the possible transport mechanism.",
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author = "Joohwan Hong and Lee, {Seung Hun} and Juhyung Kim and C.R. Seon and S.G. Lee and G.Y. Park and K.D. Lee and S.S. Henderson and H.Y. Lee and Park, {Jae Sun} and Juhyeok Jang and Siwon Jang and Taemin Jeon and M. O'Mullane and Wonhoe Choe",
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Hong, J, Lee, SH, Kim, J, Seon, CR, Lee, SG, Park, GY, Lee, KD, Henderson, SS, Lee, HY, Park, JS, Jang, J, Jang, S, Jeon, T, O'Mullane, M & Choe, W 2015, 'Control of core argon impurity profile by ECH in KSTAR L-mode plasmas' Nuclear Fusion, vol. 55, no. 6, 063016. https://doi.org/10.1088/0029-5515/55/6/063016

Control of core argon impurity profile by ECH in KSTAR L-mode plasmas. / Hong, Joohwan; Lee, Seung Hun; Kim, Juhyung; Seon, C.R.; Lee, S.G.; Park, G.Y.; Lee, K.D.; Henderson, S.S.; Lee, H.Y.; Park, Jae Sun; Jang, Juhyeok; Jang, Siwon; Jeon, Taemin; O'Mullane, M.; Choe, Wonhoe.

In: Nuclear Fusion, Vol. 55, No. 6, 063016, 06.05.2015.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Control of core argon impurity profile by ECH in KSTAR L-mode plasmas

AU - Hong, Joohwan

AU - Lee, Seung Hun

AU - Kim, Juhyung

AU - Seon, C.R.

AU - Lee, S.G.

AU - Park, G.Y.

AU - Lee, K.D.

AU - Henderson, S.S.

AU - Lee, H.Y.

AU - Park, Jae Sun

AU - Jang, Juhyeok

AU - Jang, Siwon

AU - Jeon, Taemin

AU - O'Mullane, M.

AU - Choe, Wonhoe

PY - 2015/5/6

Y1 - 2015/5/6

N2 - Experiments on trace argon impurity transport in L-mode discharges were performed on Korea superconducting tokamak advanced research (KSTAR) with electron cyclotron resonance heating (ECH). Ar emission was measured by soft x-ray (SXR) arrays and vacuum UV (VUV) diagnostics. A significant reduction in the core Ar emissivity was observed with core ECH. The reduction was the largest with on-axis heating and became smaller with outward heating positions. The diffusivity and convection velocity of Ar were obtained by analysis of the SXR data with the SANCO impurity transport code for the on-axis ECH and the non-ECH shots. In the on-axis ECH case, both diffusivity and convection velocity increased. Furthermore, the convection changed its direction from inward to outward in the plasma core (r/a?<?0.3), resulting in a hollow profile of the total Ar density. Together with the reduction in the SXR signals, the hollow impurity profile in the core and the reversal of the convection velocity consistently confirm that ECH can reduce impurity accumulation in the core region. Neoclassical impurity transport and linear stability of micro-turbulence were calculated and discussed in relation to the possible transport mechanism.

AB - Experiments on trace argon impurity transport in L-mode discharges were performed on Korea superconducting tokamak advanced research (KSTAR) with electron cyclotron resonance heating (ECH). Ar emission was measured by soft x-ray (SXR) arrays and vacuum UV (VUV) diagnostics. A significant reduction in the core Ar emissivity was observed with core ECH. The reduction was the largest with on-axis heating and became smaller with outward heating positions. The diffusivity and convection velocity of Ar were obtained by analysis of the SXR data with the SANCO impurity transport code for the on-axis ECH and the non-ECH shots. In the on-axis ECH case, both diffusivity and convection velocity increased. Furthermore, the convection changed its direction from inward to outward in the plasma core (r/a?<?0.3), resulting in a hollow profile of the total Ar density. Together with the reduction in the SXR signals, the hollow impurity profile in the core and the reversal of the convection velocity consistently confirm that ECH can reduce impurity accumulation in the core region. Neoclassical impurity transport and linear stability of micro-turbulence were calculated and discussed in relation to the possible transport mechanism.

KW - plasma impurities

KW - soft X-ray

KW - tokamaks

KW - gamma ray measurement

U2 - 10.1088/0029-5515/55/6/063016

DO - 10.1088/0029-5515/55/6/063016

M3 - Article

VL - 55

JO - Nuclear Fusion

T2 - Nuclear Fusion

JF - Nuclear Fusion

SN - 0029-5515

IS - 6

M1 - 063016

ER -