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首页> 外文期刊>Plasma physics and controlled fusion >Geodesic acoustic modes and zonal flows in rotating large-aspect-ratio tokamak plasmas
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Geodesic acoustic modes and zonal flows in rotating large-aspect-ratio tokamak plasmas

机译：旋转大纵横比托卡马克等离子体中的测地线声模和纬向流

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摘要

The effect of equilibrium plasma rotation (toroidal and poloidal) on low-frequency, electrostatic modes - the geodesic acoustic modes (GAMs) and the zonal flows (ZFs) - in large aspect ratio tokamaks is studied within the framework of ideal MHD. It is shown that the plasma rotation results in a frequency up-shift of the ordinary GAM. The new branch of continuum modes induced by the poloidal rotation is found. This mode originates from the opposite sign Doppler shift of frequency due to poloidal rotation for m = 1 poloidal side-band harmonics of the perturbed mass density, pressure and parallel velocity. In the case of slow poloidal rotation (ΩP ? cs/qR0) its frequency is close to the sound frequency cs/qR0 (ΩP is the poloidal angular velocity, cs is the speed of sound, q is the safety factor and R 0 is the major radius of tokamak). The mode can be called the rotation-induced acoustic mode. This mode disappears in the case of purely toroidal plasma rotation. The frequency of the new mode in the case of relatively slow poloidal rotation (ΩP ≤ c s/qR0) is lower than the frequency of the ordinary GAM modified by plasma rotation. In the case of larger poloidal angular velocities ΩP (ΩP ≥ 2cs/qR0) the mode becomes unstable and is identified as the unstable ZF. With a further increase in the poloidal angular velocity at constant toroidal angular velocity the instability is suppressed, and the mode turns again into a marginally stable, oscillating mode.
机译：在理想的MHD框架内，研究了大纵横比托卡马克中等离子旋转（环形和极向）对低频静电模式（测地声模（GAMs）和纬向流（ZFs））的影响。结果表明，等离子旋转导致普通GAM的频率上移。发现了由极向旋转引起的连续模式的新分支。该模式源自因扰动质量密度，压力和平行速度的m = 1倍性边带谐波而引起的极性反转引起的频率多普勒频移。在慢倍体旋转（ΩP？cs / qR0）的情况下，其频率接近于声音频率cs / qR0（ΩP是极角速度，cs是声速，q是安全系数，R 0是声速托卡马克的主要半径）。该模式可以称为旋转感应声模式。在纯环形等离子体旋转的情况下，此模式消失。在极慢的极向旋转（ΩP≤c s / qR0）的情况下，新模式的频率低于通过等离子体旋转修改的普通GAM的频率。在较大的极角速度ΩP（ΩP≥2cs / qR0）的情况下，该模式变得不稳定，并被识别为不稳定的ZF。随着在恒定的环形角速度下的极向角速度的进一步增加，不稳定性被抑制，并且该模式再次变为边缘稳定的振荡模式。

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