Toroidal injection angle dependence of EC assisted plasma initiation at DIII-D

J. Yang; A. C.C. Sips; P. de Vries; J. Sinha; H. T. Kim; F. Glass; M. Austin; M. van Zeeland; J. L. Herfindal; M. Shafer; A. O. Nelson; C. Marini; M. G. Yoo

doi:10.1088/1741-4326/ad8a6f

Toroidal injection angle dependence of EC assisted plasma initiation at DIII-D

J. Yang, A. C.C. Sips, P. de Vries, J. Sinha, H. T. Kim, F. Glass, M. Austin, M. van Zeeland, J. L. Herfindal, M. Shafer, A. O. Nelson, C. Marini, M. G. Yoo

Advanced Tokamak Physics

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

Abstract

An experimental scan of the electron cyclotron waves (EC) toroidal injection angle in plasma breakdown is performed at the DIII-D tokamak. The second harmonic, extraordinary mode EC is used for the study. The dependence of n_e and T_e on the EC injection angle cannot be conclusively drawn from this study due to the large error bars in the n_e and T_e measurements. On the other hand, high T_e data points are observed in some discharges which can be explained by nonlinear heating. The D_α emission measurement shows a clear relation between the breakdown time and the injection angle. An experimental investigation of the cause of the dependence of breakdown delay on the EC injection angle suggests that when the injection angle is oblique, the EC heating after the reflection at the inboard wall may become ineffective and cause the breakdown delay even when the EC heating before and directly upon injection remains effective. A preliminary run of the heat and transport balance code DYON indicates that the obtained dataset is suitable for a quantitative validation of EC absorption models.

Original language	English
Article number	126065
Journal	Nuclear Fusion
Volume	64
Issue number	12
DOIs	https://doi.org/10.1088/1741-4326/ad8a6f
State	Published - Dec 2024

Funding

The authors gratefully acknowledge Mike Walker for his leadership. The first author also thanks Masayuki Ono and Mario Podest\u00E0 for their insightful comments. This work was supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under DE-AC02-09CH11466, DE-AC05-00OR22725, DE-FC02-04ER54698, DE-FG02-97ER54415, DE-SC0022270, and DE-FG02-07ER54917. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization. This publication is provided for scientific purposes only.

Funders	Funder number
Office of Science
U.S. Department of Energy
Fusion Energy Sciences	DE-AC05-00OR22725, DE-AC02-09CH11466, DE-FC02-04ER54698, DE-SC0022270, DE-FG02-07ER54917, DE-FG02-97ER54415
Fusion Energy Sciences

Keywords

electron cyclotron waves
plasma initiation
tokamak

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

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10.1088/1741-4326/ad8a6f

Cite this

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title = "Toroidal injection angle dependence of EC assisted plasma initiation at DIII-D",

abstract = "An experimental scan of the electron cyclotron waves (EC) toroidal injection angle in plasma breakdown is performed at the DIII-D tokamak. The second harmonic, extraordinary mode EC is used for the study. The dependence of ne and Te on the EC injection angle cannot be conclusively drawn from this study due to the large error bars in the ne and Te measurements. On the other hand, high Te data points are observed in some discharges which can be explained by nonlinear heating. The Dα emission measurement shows a clear relation between the breakdown time and the injection angle. An experimental investigation of the cause of the dependence of breakdown delay on the EC injection angle suggests that when the injection angle is oblique, the EC heating after the reflection at the inboard wall may become ineffective and cause the breakdown delay even when the EC heating before and directly upon injection remains effective. A preliminary run of the heat and transport balance code DYON indicates that the obtained dataset is suitable for a quantitative validation of EC absorption models.",

keywords = "electron cyclotron waves, plasma initiation, tokamak",

author = "J. Yang and Sips, {A. C.C.} and {de Vries}, P. and J. Sinha and Kim, {H. T.} and F. Glass and M. Austin and {van Zeeland}, M. and Herfindal, {J. L.} and M. Shafer and Nelson, {A. O.} and C. Marini and Yoo, {M. G.}",

note = "Publisher Copyright: {\textcopyright} 2024 The Author(s). Published by IOP Publishing Ltd on behalf of the IAEA.",

year = "2024",

month = dec,

doi = "10.1088/1741-4326/ad8a6f",

language = "English",

volume = "64",

journal = "Nuclear Fusion",

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T1 - Toroidal injection angle dependence of EC assisted plasma initiation at DIII-D

AU - Yang, J.

AU - Sips, A. C.C.

AU - de Vries, P.

AU - Sinha, J.

AU - Kim, H. T.

AU - Glass, F.

AU - Austin, M.

AU - van Zeeland, M.

AU - Herfindal, J. L.

AU - Shafer, M.

AU - Nelson, A. O.

AU - Marini, C.

AU - Yoo, M. G.

PY - 2024/12

Y1 - 2024/12

N2 - An experimental scan of the electron cyclotron waves (EC) toroidal injection angle in plasma breakdown is performed at the DIII-D tokamak. The second harmonic, extraordinary mode EC is used for the study. The dependence of ne and Te on the EC injection angle cannot be conclusively drawn from this study due to the large error bars in the ne and Te measurements. On the other hand, high Te data points are observed in some discharges which can be explained by nonlinear heating. The Dα emission measurement shows a clear relation between the breakdown time and the injection angle. An experimental investigation of the cause of the dependence of breakdown delay on the EC injection angle suggests that when the injection angle is oblique, the EC heating after the reflection at the inboard wall may become ineffective and cause the breakdown delay even when the EC heating before and directly upon injection remains effective. A preliminary run of the heat and transport balance code DYON indicates that the obtained dataset is suitable for a quantitative validation of EC absorption models.

AB - An experimental scan of the electron cyclotron waves (EC) toroidal injection angle in plasma breakdown is performed at the DIII-D tokamak. The second harmonic, extraordinary mode EC is used for the study. The dependence of ne and Te on the EC injection angle cannot be conclusively drawn from this study due to the large error bars in the ne and Te measurements. On the other hand, high Te data points are observed in some discharges which can be explained by nonlinear heating. The Dα emission measurement shows a clear relation between the breakdown time and the injection angle. An experimental investigation of the cause of the dependence of breakdown delay on the EC injection angle suggests that when the injection angle is oblique, the EC heating after the reflection at the inboard wall may become ineffective and cause the breakdown delay even when the EC heating before and directly upon injection remains effective. A preliminary run of the heat and transport balance code DYON indicates that the obtained dataset is suitable for a quantitative validation of EC absorption models.

KW - electron cyclotron waves

KW - plasma initiation

KW - tokamak

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U2 - 10.1088/1741-4326/ad8a6f

DO - 10.1088/1741-4326/ad8a6f

M3 - Article

AN - SCOPUS:85209219379

SN - 0029-5515

VL - 64

JO - Nuclear Fusion

JF - Nuclear Fusion

IS - 12

M1 - 126065

ER -

Toroidal injection angle dependence of EC assisted plasma initiation at DIII-D

Abstract

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Keywords

UN SDGs

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