Abstract

The study is continued of the temporal changes of the parameters of turbulent plasma density fluctuations during multi-pulse electron cyclotron (EC) heating of the plasma on the L-2M stellarator. The plasma density fluctuations with different wave vectors (k = 30, 20, 2, and 1 cm ^–1) in different spatial regions of the plasma column were recorded by the method of collective scattering of microwave radiation. The time dependence of plasma density fluctuations, which has a bursty shape, was analyzed, including the discharges in which the gyroresonance region was shifted by 3–4 cm from the center of the plasma column toward the inside of the torus. A comparison was made between the specificities of the evolution of plasma density fluctuations and the evolution of their statistical characteristics. It was found that the kurtosis (M4) of the scattering signals deviates from the value 3, which also occurs in bursts. During a EC heating pulse, three groups of different bursts (of signal intensity, its kurtosis and their increments) were observed. Autocorrelation analysis of density fluctuations and their increment was carried out and it showed that the half-width of the autocorrelation functions changes during multi-pulse EC heating. The probability of the initiation of bursty processes by perturbations in the near-wall plasma region is discussed.

中文翻译：

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在L-2M恒星发生器的等离子体脉冲EC加热期间，湍流密度波动参数的时空演变

摘要

继续研究在L-2M恒星发生器上的等离子体多脉冲电子回旋加速器（EC）加热期间湍流等离子体密度波动参数的时间变化。等离子体密度随不同波矢量而波动（k = 30、20、2和1 cm ^–1用微波辐射的集体散射法记录了等离子柱不同空间区域内的）。分析了具有爆裂形状的等离子体密度波动的时间依赖性，包括放电，其中回旋共振区域从等离子体柱的中心向圆环内部偏移了3–4 cm。在血浆密度波动演变的特异性及其统计特征的演变之间进行了比较。发现散射信号的峰度（M4）偏离值3，该值也以突发形式出现。在EC加热脉冲期间，观察到三组不同的突发（信号强度，峰度及其增量）。进行了密度波动及其增量的自相关分析，结果表明，在多脉冲EC加热过程中，自相关函数的半角宽度发生了变化。讨论了由近壁等离子体区域中的扰动引发的爆发过程的可能性。