Study of Gam Characteristics in the T-10 Tokamak

XXXVII international conference on plasma physics and CF, February 8 – 12, 2010, Zvenigorod.

STUDY OF GAM CHARACTERISTICS IN THE T-10 TOKAMAK

A.V. Melnikov, V.A. Vershkov, S.A. Grashin, L.G. Eliseev, S.E. Lysenko, V.A.°Mavrin, S.V. Perfilov, D.A. Shelukhin, R.V. Shurygin, L.I. Krupnik*, A.I. Zhezhera*, A.D.Komarov*, A.S. Kozachok*

Tokamak Physics Institute, RRC "Kurchatov Institute", 123182, Moscow, Russia,
e-mail:
*NSC “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine

Zonal flows and their high-frequency branch, the geodesic acoustic modes (GAMs) are considered as a possible mechanism of the plasma turbulence self-regulation. In the T-10 tokamak, GAMs have been studied by the heavy ion beam probing (HIBP), correlation reflectometry (CR) and multipin Langmuir probes [1].

The regimes with ohmic, and on-axis and off-axis electron cyclotron heating (ECRH) are studied (B = 1.5–2.4 T, Ip = 140-250 kA, ne = (0.7 – 3) ´ 1019 m-3, PEC < 1.5 MW). One antenna of CR was located in the same port with HIBP, and other antennas were shifted along 1/4 of torus. Correlation measurements performed by these diagnostics allowed us to define the toroidal and poloidal structure of GAMs.

It was shown that GAM has complicated, radially inhomogeneous structure. The spatial limits of GAM existence depend on the plasma parameters. GAMs are more pronounced during ECRH, when the typical frequencies were seen in the narrow band from 22 to 27 kHz at the outward 1/3 part of plasma cross-section. GAM characteristics and limits of GAM existence were investigated as functions of density, magnetic field, safety factor and ECRH power. T-10 data are compared with data obtained in other tokamaks and stellerators [2].

This work is supported by Contract FASI 02.740.11.5062 and Grants RFBR 08-02-90468-Ukr, 08-02-01326, NWO-RFBR 047.018.002.

References.

[1].  Melnikov A.V. et al., Plasma Phys. Control. Fusion 2006, 48, S87.

[2].  Fujisawa A., Nucl. Fusion, 2009, 49, 013001.

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