Abstract
A plasma confinement mode characterized by the formation of an edge transport barrier (ETB) was discovered in the L-2M stellarator after boronization of the vacuum vessel wall. The transition into this mode is accompanied by a jump in the electron temperature by 100–200 eV at the plasma edge and a sharp increase in the gradient of the electron temperature T e in this region. The threshold power for the transition into the ETB confinement mode with an increased electron temperature gradient is P ▿Tethr = (60 ± 15)n e [1019 m−3] kW. The formation of the ETB manifests itself also in a substantial change in the electron density profile. A density peak with a steep gradient at the outer side forms at the plasma edge. The threshold power for the transition into the ETB confinement mode corresponding to a substantial increase in the plasma density gradient near r = a is P ▿Tethr = (67 ± 9)n e [1019 m−3] kW, which agrees to within experimental error with the threshold power for the transition into the ETB confinement mode determined from the sharp increase in the gradient of the electron temperature T e . The value of P thr for the L-2M stellarator agrees to within 25% with that obtained from the tokamak scaling. In the ETB confinement mode, the plasma energy W and the energy confinement time τ E determined from diamagnetic measurements increase by 20–30% as compared to those obtained from the stellarator scaling for the confinement mode without an ETB. When the heating power increases by a factor of 2–3 above the threshold value, the effects related to improved energy confinement disappear.
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Original Russian Text © G.S. Voronov, D.K. Akulina, G.M. Batanov, M.S. Berezhetskii, D.G. Vasil’kov, I.Yu. Vafin, E.V. Voronova, S.E. Grebenshchikov, I.A. Grishina, L.V. Kolik, N.F. Larionova, V.P. Logvinenko, D.V. Malakhov, A.I. Meshcheryakov, Yu.I. Nechaev, A.E. Petrov, K.A. Sarksyan, V.V. Saenko, N.N. Skvortsova, O.I. Fedyanin, N.K. Kharchev, Yu.V. Khol’nov, S.V. Shchepetov, 2010, published in Fizika Plazmy, 2010, Vol. 36, No. 7, pp. 595–601.
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Voronov, G.S., Akulina, D.K., Batanov, G.M. et al. Study of plasma confinement in the L-2M stellarator during the formation of an edge transport barrier. Plasma Phys. Rep. 36, 551–557 (2010). https://doi.org/10.1134/S1063780X10070020
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DOI: https://doi.org/10.1134/S1063780X10070020