Email this article Transition into the improved core confinement mode as a possible mechanism for additional electron heating observed in the lower hybrid current drive experiments at the FT-2 tokamak
- Authors: Altukhov A.B.1, Gurchenko A.D.1, Gusakov E.Z.1, Dyachenko V.V.1, Esipov L.A.1, Irzak M.A.1, Kantor M.Y.1, Kouprienko D.V.1, Perevalov A.A.2, Saveliev A.N.1, Stepanov A.Y.1, Shatalin S.V.2, Lashkul S.I.1
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Affiliations:
- Ioffe Institute
- St. Petersburg Politechnical University
- Issue: Vol 43, No 7 (2017)
- Pages: 711-719
- Section: Tokamaks
- URL: https://journals.rcsi.science/1063-780X/article/view/186121
- DOI: https://doi.org/10.1134/S1063780X1707008X
- ID: 186121
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Abstract
In experiments on lower hybrid current drive (LHCD) carried out at the FT-2 tokamak, a substantial increase in the central electron temperature Te(r = 0 cm) from 550 to 700 eV was observed. A complex simulation procedure is used to explain a fairly high LHCD efficiency and the observed additional heating, which can be attributed to a transition into the improved core confinement (ICC) mode. For numerical simulations, data obtained in experiments with deuterium plasma at 〈ne〉 = 1.6 × 1019 m–3 were used. Simulations by the GRILL3D, FRTC, and ASTRA codes have shown that the increase in the density and central temperature is apparently caused by a significant suppression of heat transport in the electron component. The mechanism for transition into the improved confinement mode at r < 3 cm can be associated with the broadening of the plasma current channel due to the lower hybrid drive of the current carried by superthermal and runaway electrons. In this case, the magnetic shear s = (r/q)(dq/dr) in the axial region of the plasma column almost vanishes during the RF pulse. In this study, the effect of lower hybrid waves on the plasma parameters, resulting in a transition into the ICC mode, is considered. New experimental and calculated data are presented that evidence in favor of such a transition. Special attention is paid to the existence of a threshold for the transition into the ICC mode in deuterium plasma.
About the authors
A. B. Altukhov
Ioffe Institute
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021
A. D. Gurchenko
Ioffe Institute
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021
E. Z. Gusakov
Ioffe Institute
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021
V. V. Dyachenko
Ioffe Institute
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021
L. A. Esipov
Ioffe Institute
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021
M. A. Irzak
Ioffe Institute
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021
M. Yu. Kantor
Ioffe Institute
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021
D. V. Kouprienko
Ioffe Institute
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021
A. A. Perevalov
St. Petersburg Politechnical University
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 195251
A. N. Saveliev
Ioffe Institute
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021
A. Yu. Stepanov
Ioffe Institute
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021
S. V. Shatalin
St. Petersburg Politechnical University
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 195251
S. I. Lashkul
Ioffe Institute
Author for correspondence.
Email: Serguey.Lashkul@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021
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