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


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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.

Sobre autores

A. Altukhov

Ioffe Institute

Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 194021

A. Gurchenko

Ioffe Institute

Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 194021

E. Gusakov

Ioffe Institute

Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 194021

V. Dyachenko

Ioffe Institute

Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 194021

L. Esipov

Ioffe Institute

Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 194021

M. Irzak

Ioffe Institute

Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 194021

M. Kantor

Ioffe Institute

Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 194021

D. Kouprienko

Ioffe Institute

Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 194021

A. Perevalov

St. Petersburg Politechnical University

Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 195251

A. Saveliev

Ioffe Institute

Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 194021

A. Stepanov

Ioffe Institute

Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 194021

S. Shatalin

St. Petersburg Politechnical University

Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 195251

S. Lashkul

Ioffe Institute

Autor responsável pela correspondência
Email: Serguey.Lashkul@mail.ioffe.ru
Rússia, St. Petersburg, 194021

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