ADDENDUM: Zonal flow and streamer generation in drift turbulence
ADDENDUM: Zonal flow and streamer generation in drift turbulence
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附录：漂移湍流中的纬向流和流光生成
DOI：
10.1088/0741-3335/43/7/402
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发表时间：
2001
影响因子：
2.2
通讯作者：
R. Dendy
中科院分区：
文献类型：
--
作者：
G. Manfredi;C. Roach;R. Dendy
极向扩展纬向流(kθ=0，KR≠0)和径向扩展流(kθ≠0，KR=0)在调节漂移湍流能量传输中的相对重要性是托卡马克物理中的一个中心问题。这两种形式的非线性结构都可以在Smolyakov等人(Smolyakov A i，Diamond P H和Malkov M 2000 Phys)推广的长谷川-米玛方程的框架内描述。莱特牧师。84 491)，尽管以前没有在这方面进行过分析。在这里，我们介绍了通过比较解析弱湍流计算和使用谱代码的数值模拟所获得的结果。分析结果采用四波模型，其中包含一个漂移波(K2)通过纬向流或流光(K1)耦合到两个边带(K2±K1)。我们对这个四波系统进行了完全的非线性研究，我们发现由波耦合模型得到的解析表达式对谱程序的结果有很好的指导作用。发现了不稳定条件，并计算了增长率，表明纬向流比飘流更不稳定，至少在这种描述水平上是这样。典型地，我们发现流光增长率比纬向流的增长率低一个数量级的ρSK1。由于我们的长谷川-米玛模型包含了更复杂方法的许多核心物理元素，这些结果对托卡马克漂移湍流的数值模拟具有更广泛的重要性。
The relative importance of poloidally extended zonal flows (kθ = 0, kr≠0) and radially extended streamers (kθ≠0, kr = 0) in regulating drift turbulent energy transport is a central question in tokamak physics. Both forms of nonlinear structure can be described within the framework of the Hasegawa-Mima equation, as extended by Smolyakov et al (Smolyakov A I, Diamond P H and Malkov M 2000 Phys. Rev. Lett. 84 491), although streamers have not previously been analysed in this context. Here we present results obtained by comparing analytical weak-turbulence calculations with numerical simulations using a spectral code. The analytical results are obtained with a four-wave model, incorporating a drift wave (k2) coupled to both sidebands (k2±k1) by a zonal flow or streamer (k1). Fully nonlinear studies of this four-wave system have been carried out, and we find that analytical expressions derived from wave coupling models provide a good guide to the spectral code results. Instability conditions are found and growth rates computed, showing that zonal flows are more unstable than streamers, at least at this level of description. Typically, we find that the streamer growth rate is lower than that of the zonal flow by a factor of order ρsk1. Insofar as our Hasegawa-Mima model contains many of the core physics elements of more sophisticated approaches, these results are of wider importance to the numerical modelling of drift turbulence in tokamaks.