Kink instabilities in high-beta JET advanced scenarios

P. Buratti, M. Baruzzo, R.J. Buttery, C.D. Challis, I.T. Chapman, F. Crisanti, L. Figini, M. Gryaznevich, T.C. Hender, D.F. Howell, H. Han, F. Imbeaux, E. Joffrin, J. Hobirk, O.J. Kwon, X. Litaudon, J. Mailloux

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Abstract

Stability of high-beta plasmas is studied on discharges from a series of JET experiments on steady-state and hybrid advanced scenarios, with a wide range of safety factor (q) profiles and normalized beta values extending to β N = 4. Bursting and continuous forms of global n = 1 instabilities are encountered that degrade confinement or, in some cases, give rise to disruptions. Mode frequencies are well above the inverse wall time and correspond to plasma rotation at around mid-radius. Stability boundaries in terms of q min and pressure peaking are examined. For relatively broad pressure profiles the stability limit decreases from β N = 4 at q min = 1 to β N = 2 at q min = 3, while at fixed q min it decreases with increasing pressure peaking. Metastable and unstable regions are identified in the β N-q min diagram by mode-trigger analysis. Tearing and kink mode structures are found from phase analysis of temperature profile oscillations; for a selection of kink cases, instability conditions and mode structure are compared with ideal stability calculations. © 2012 IAEA, Vienna.
Original languageEnglish
Article number023006
Pages (from-to)-
JournalNuclear Fusion
Volume52
Issue number2
DOIs
Publication statusPublished - Feb 2012
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Nuclear and High Energy Physics

Cite this

Buratti, P., Baruzzo, M., Buttery, R. J., Challis, C. D., Chapman, I. T., Crisanti, F., Figini, L., Gryaznevich, M., Hender, T. C., Howell, D. F., Han, H., Imbeaux, F., Joffrin, E., Hobirk, J., Kwon, O. J., Litaudon, X., & Mailloux, J. (2012). Kink instabilities in high-beta JET advanced scenarios. Nuclear Fusion, 52(2), -. [023006]. https://doi.org/10.1088/0029-5515/52/2/023006