Reciprocating Probe Measurements of L-H Transition in LHCD H-mode on EAST

Liu Peng, Xu Guosheng, Wang Huiqian, Jiang Min, Wang Liang, Zhang Wei, Liu Shaocheng, Ning Yan, Ding Siye

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode (H-mode) with low heating power will be a critical issue. In the recent experiment on EAST, the H-mode was obtained for the first time with lower hybrid current drive (LHCD) wave only. Reciprocating Langmuir probe measurements at the outer midplane showed that the electron density ne and electron temperature Te in the scrape-off layer (SOL) were significantly reduced in the ELM-free phase, resulting in the increase of lower-hybrid wave (LHW) reflection. It was found that the power loss P loss was comparable during the L-H transition, by comparing the adjacent L-mode and H-mode discharge. The Dα emission, Te and ne decreased rapidly in the time scale of about 1 ms, and the radial electric field Er turned positive in this process near the last closed flux surface. Multiple L-H-L transitions were observed during a single shot when the applied LHW power was marginal to the threshold. The floating potential (Vf) had negative spikes corresponding with the Dα signal, and Er oscillation evolved into several intermittent negative spikes just before the L-H transition. In some shots, dithering was observed just before the L-H transition.
Original languageEnglish
JournalPlasma Science and Technology
Volume15
Issue number7
Pages (from-to)619-622
ISSN1009-0630
Publication statusPublished - 2013

Cite this

Peng, L., Guosheng, X., Huiqian, W., Min, J., Liang, W., Wei, Z., ... Siye, D. (2013). Reciprocating Probe Measurements of L-H Transition in LHCD H-mode on EAST. Plasma Science and Technology, 15(7), 619-622.
Peng, Liu ; Guosheng, Xu ; Huiqian, Wang ; Min, Jiang ; Liang, Wang ; Wei, Zhang ; Shaocheng, Liu ; Yan, Ning ; Siye, Ding. / Reciprocating Probe Measurements of L-H Transition in LHCD H-mode on EAST. In: Plasma Science and Technology. 2013 ; Vol. 15, No. 7. pp. 619-622.
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title = "Reciprocating Probe Measurements of L-H Transition in LHCD H-mode on EAST",
abstract = "As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode (H-mode) with low heating power will be a critical issue. In the recent experiment on EAST, the H-mode was obtained for the first time with lower hybrid current drive (LHCD) wave only. Reciprocating Langmuir probe measurements at the outer midplane showed that the electron density ne and electron temperature Te in the scrape-off layer (SOL) were significantly reduced in the ELM-free phase, resulting in the increase of lower-hybrid wave (LHW) reflection. It was found that the power loss P loss was comparable during the L-H transition, by comparing the adjacent L-mode and H-mode discharge. The Dα emission, Te and ne decreased rapidly in the time scale of about 1 ms, and the radial electric field Er turned positive in this process near the last closed flux surface. Multiple L-H-L transitions were observed during a single shot when the applied LHW power was marginal to the threshold. The floating potential (Vf) had negative spikes corresponding with the Dα signal, and Er oscillation evolved into several intermittent negative spikes just before the L-H transition. In some shots, dithering was observed just before the L-H transition.",
author = "Liu Peng and Xu Guosheng and Wang Huiqian and Jiang Min and Wang Liang and Zhang Wei and Liu Shaocheng and Ning Yan and Ding Siye",
year = "2013",
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Peng, L, Guosheng, X, Huiqian, W, Min, J, Liang, W, Wei, Z, Shaocheng, L, Yan, N & Siye, D 2013, 'Reciprocating Probe Measurements of L-H Transition in LHCD H-mode on EAST', Plasma Science and Technology, vol. 15, no. 7, pp. 619-622.

Reciprocating Probe Measurements of L-H Transition in LHCD H-mode on EAST. / Peng, Liu ; Guosheng, Xu; Huiqian, Wang; Min, Jiang; Liang, Wang; Wei, Zhang; Shaocheng, Liu; Yan, Ning; Siye, Ding.

In: Plasma Science and Technology, Vol. 15, No. 7, 2013, p. 619-622.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Reciprocating Probe Measurements of L-H Transition in LHCD H-mode on EAST

AU - Peng, Liu

AU - Guosheng, Xu

AU - Huiqian, Wang

AU - Min, Jiang

AU - Liang, Wang

AU - Wei, Zhang

AU - Shaocheng, Liu

AU - Yan, Ning

AU - Siye, Ding

PY - 2013

Y1 - 2013

N2 - As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode (H-mode) with low heating power will be a critical issue. In the recent experiment on EAST, the H-mode was obtained for the first time with lower hybrid current drive (LHCD) wave only. Reciprocating Langmuir probe measurements at the outer midplane showed that the electron density ne and electron temperature Te in the scrape-off layer (SOL) were significantly reduced in the ELM-free phase, resulting in the increase of lower-hybrid wave (LHW) reflection. It was found that the power loss P loss was comparable during the L-H transition, by comparing the adjacent L-mode and H-mode discharge. The Dα emission, Te and ne decreased rapidly in the time scale of about 1 ms, and the radial electric field Er turned positive in this process near the last closed flux surface. Multiple L-H-L transitions were observed during a single shot when the applied LHW power was marginal to the threshold. The floating potential (Vf) had negative spikes corresponding with the Dα signal, and Er oscillation evolved into several intermittent negative spikes just before the L-H transition. In some shots, dithering was observed just before the L-H transition.

AB - As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode (H-mode) with low heating power will be a critical issue. In the recent experiment on EAST, the H-mode was obtained for the first time with lower hybrid current drive (LHCD) wave only. Reciprocating Langmuir probe measurements at the outer midplane showed that the electron density ne and electron temperature Te in the scrape-off layer (SOL) were significantly reduced in the ELM-free phase, resulting in the increase of lower-hybrid wave (LHW) reflection. It was found that the power loss P loss was comparable during the L-H transition, by comparing the adjacent L-mode and H-mode discharge. The Dα emission, Te and ne decreased rapidly in the time scale of about 1 ms, and the radial electric field Er turned positive in this process near the last closed flux surface. Multiple L-H-L transitions were observed during a single shot when the applied LHW power was marginal to the threshold. The floating potential (Vf) had negative spikes corresponding with the Dα signal, and Er oscillation evolved into several intermittent negative spikes just before the L-H transition. In some shots, dithering was observed just before the L-H transition.

M3 - Journal article

VL - 15

SP - 619

EP - 622

JO - Plasma Science and Technology

JF - Plasma Science and Technology

SN - 1009-0630

IS - 7

ER -

Peng L, Guosheng X, Huiqian W, Min J, Liang W, Wei Z et al. Reciprocating Probe Measurements of L-H Transition in LHCD H-mode on EAST. Plasma Science and Technology. 2013;15(7):619-622.