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

Yang, J.; Sips, A. C. C.; de Vries, P.; Sinha, J.; Kim, H. T.; Glass, Fenton; Austin, M.; van Zeeland, Michael; Herfindal, Jeffrey L.; Shafer, Morgan; Nelson, A. O.; Marini, Claudio; Yoo, M. G.

doi:10.1088/1741-4326/ad8a6f

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

Journal Article · 03 November 2024 · Nuclear Fusion

DOI: https://doi.org/10.1088/1741-4326/ad8a6f · OSTI ID:2475882

^[1]; Sips, A. C. C. ^[2];

^[3]; Sinha, J. ^[4];

^[5]; Glass, Fenton ^[2]; Austin, M. ^[6];

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Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
General Atomics, San Diego, CA (United States)
ITER Organization, St Paul Lez Durance (France)
Tokamak Energy Ltd, Oxfordshire (United Kingdom of Great Britain and Northern Ireland)
United Kingdom Atomic Energy Authority, Abingdon (United Kingdom of Great Britain and Northern Ireland)
University of Texas, Austin, TX (United States)
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Columbia University, New York, NY (United States)
University of California San Diego, La Jolla, CA (United States)

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.

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Research Organization:: General Atomics, San Diego, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: USDOE; USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Grant/Contract Number:: AC02-09CH11466; AC05-00OR22725; FC02-04ER54698; FG02-07ER54917; FG02-97ER54415; SC0022270

OSTI ID:: 2475882

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 12 Vol. 64; ISSN 0029-5515

Publisher:: IOP Science - IAEACopyright Statement

Country of Publication:: United States

Language:: English

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