Correlation of the tokamak H-mode density limit with ballooning stability at the separatrix

Eich, T.; Goldston, R. J.; Kallenbach, A.; Sieglin, B.; Sun, H. J.

doi:10.1088/1741-4326/aaa340

Title: Correlation of the tokamak H-mode density limit with ballooning stability at the separatrix

Journal Article · Mon Jan 15 00:00:00 EST 2018 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/aaa340· OSTI ID:1473625

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^[1]; Sieglin, B. ^[1]; Sun, H. J. ^[1]

Max Planck Inst. for Plasma Physics, Garching (Germany)
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

We show for JET and ASDEX Upgrade, based on Thomson-scattering measurements, a clear correlation of the density limit of the tokamak H-Mode highcon nement regime with the approach to the ideal ballooning instability threshold at the periphery of the plasma. It is shown that the MHD ballooning parameter at the separatrix position αsep increases about linearly with the separatrix density normalized to Greenwald density, n_e,sep=n_GW for a wide range of discharge parameters in both devices. The observed operational space is found to reach at maximum n_e,sep=nGW ≈ 0.4-0.5 at values for α_sep ≈ 2-2.5, in the range of theoretical predictions for ballooning instability. This work supports the hypothesis that the H-Mode density limit may be set by ballooning stability at the separatrix.

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Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: USDOE

Contributing Organization:: ASDEX Upgrade Team; JET Contributors

Grant/Contract Number:: AC02-09CH11466

OSTI ID:: 1473625

Journal Information:: Nuclear Fusion, Vol. 58, Issue 3; Related Information: This work has been carried out within the framework of the EUROfusion Consortiumand has received funding from the Euratom research and training programme 2014-2018under grant agreement No 633053. The views and opinions expressed herein do notnecessarily reflect those of the European Commission. The work of RJG was supportedby US DOE Contract No. DE-AC02-09CH11466; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 46 works

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