抄録
Zonal flows and their high-frequency counterpart, the geodesic acoustic modes (GAMs) are considered as a possible mechanism of the plasma turbulence self-regulation. In the T-10 tokamak, GAM and broadband (< 200 kHz) turbulence of plasma potential and density have been directly studied by heavy ion beam probing from the plasma core to the edge. Regimes with Ohmic and auxiliary electron cyclotron resonance heating (ECRH) were studied (Bt = 1.7 - 2.4 T, Ip = 140 - 250 kA, ne = (0.6 - 3)× 1019 m−3, PEC ≤ 1.2 MW) for the plasma with tungsten rail limiter. GAMs are more pronounced during ECRH, when the typical frequencies fGAM were in the band 22 - 27 kHz for the main frequency peak and 25 - 30 kHz for the higher frequency satellite. Both GAM and satellite have uniform structure with constant frequencies over a wide radial extension, exhibiting the features of plasma eigenmodes. The main GAM peak has wider outer bound at the plasma edge than satellite. fGAM follows the theoretical expectation fGAM ∼ √T/mi /R (for electron temperature at r/a = 0.7) for both OH and ECRH regimes in the wide temperature area, covering the whole operational limit of T-10. At the plasma periphery, the quasicoherent electrostatic mode with frequency 50 - 120 kHz coexists with GAM and satellite.
