Stationary advanced scenarios with internal transport barrier on ASDEX Upgrade

Authors: Wolf R.C.¹; Gruber O.¹; Maraschek M.¹; Dux R.¹; Fuchs C.¹; Günter S.¹; Herrmann A.¹; Kallenbach A.¹; Lackner K.¹; McCarthy P.J.²; Meister H.¹; Pereverzev G.¹; Schweinzer J.¹; Seidel U.¹; Team t.A.U.¹

Source: Plasma Physics and Controlled Fusion, Volume 41, Number 12B, 1999 , pp. B93-B107(15)

Publisher: IOP Publishing

Abstract:

Steady-state discharges with improved core confinement and H-mode edge with edge localized modes (ELMs) are investigated. In plasmas with an upper triangularity _top close to zero an H-factor of H_ITER89-P = 2.7 and _N = 2.2 could be maintained for 1 s and H_ITER89-P = 2.4 and _N = 2.0 for 6 s, the latter corresponding to 40 confinement times or 2 1/2 resistive time scales for current redistribution, only limited by the duration of the possible discharge length. At a line averaged density of 4 ? 10¹⁹ m^-3 the central temperatures reach values of T_i = 10 keV and T_e = 6.5 keV. The stationarity of the current profile is explained by magnetic reconnection driven by strong (m = 1, n = 1) fishbones, which, in the absence of sawteeth, also expel energy and impurities. Further increasing the pressure, is limited by neoclassical tearing modes. Raising the density by edge gas fuelling and the simultaneous increase of the neutral beam power, H_ITER89-P remained unchanged up to n_e = 5.5 ? 10¹⁹ m^-3, accompanied by a substantial reduction of Z_eff. Increasing _top to 0.2, both confinement and -limit improved reaching values of H_ITER89-P = 3.0 and _N = 2.4 at densities above n_e = 5 ? 10¹⁹ m^-3. This resulted in the highest fusion product of n_D,0T_i,0E = 0.9 ? 10²⁰ keV s m^-3 so far observed in ASDEX Upgrade.

Language: English

Document Type: Miscellaneous

Affiliations: 1: Max-Planck-Institut für Plasmaphysik, EURATOM-Association, D-85748 Garching, Germany 2: University College Cork, Association EURATOM-DCU, Cork, Ireland

Publication date: 1999-01-01

• In this: publication
• By this: publisher
• In this Subject: Electricity & Magnetism ,  Nuclear Physics
• By this author: Wolf R.C. ;  Gruber O. ;  Maraschek M. ;  Dux R. ;  Fuchs C. ;  Günter S. ;  Herrmann A. ;  Kallenbach A. ;  Lackner K. ;  McCarthy P.J. ;  Meister H. ;  Pereverzev G. ;  Schweinzer J. ;  Seidel U. ;  Team t.A.U.

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