Abstract

The Alfvén oscillations were studied using the multifrequency Doppler backscattering (DBS) method on the Globus-M spherical tokamak during the neutral deuterium injection. The principles of Alfvén mode registration by the DBS method are discussed. Microwave schemes of multifrequency probing are described. It is shown that the observed plasma rotation velocity oscillations are due to the oscillations of the drift velocity in crossed radial electric field of the Alfvén wave and the magnetic field. The absolute values of the magnetic field perturbations of the toroidal Alfvén eigenmode (TAE) in the internal regions of the tokamak discharge are determined. The obtained data are compared with the results of the magnetic field oscillations measurements obtained by a magnetic probe located outside the plasma region. The use of multifrequency probing in the DBS method made it possible to determine the radial distributions of the amplitude of magnetic field oscillations. These data were obtained for oscillations at the TAE fundamental frequency and at harmonic frequencies, which were found to correspond to different toroidal mode numbers. In general, the data obtained can be compared with the results of numerical modeling of the Alfvén spectrum in the Globus-M tokamak. The prospects for the further use of the DBS method for studying Alfvén oscillations in toroidal installations are discussed.

中文翻译：

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多普勒反向散射在Globus-M球形托卡马克Alfvén模式研究中的应用

摘要

在中性氘注入过程中，使用多频多普勒反向散射（DBS）方法对Globus-M球形托卡马克进行了Alfvén振荡研究。讨论了通过DBS方法进行Alfvén模式注册的原理。描述了多频探测的微波方案。结果表明，观察到的等离子体转速振荡是由于Alfvén波的交叉径向电场和磁场中漂移速度的振荡引起的。确定了托卡马克放电内部区域中的环形Alfvén本征模（TAE）的磁场扰动的绝对值。将获得的数据与位于等离子体区域外部的磁探针获得的磁场振荡测量结果进行比较。DBS方法中多频探测的使用使得确定磁场振荡幅度的径向分布成为可能。这些数据是针对TAE基频和谐波频率下的振荡而获得的，发现它们对应于不同的环形模数。通常，可以将获得的数据与Globus-M托卡马克中Alfvén光谱的数值模拟结果进行比较。讨论了进一步使用DBS方法研究环形装置中Alfvén振动的前景。发现它们对应于不同的环形模式编号。通常，可以将获得的数据与Globus-M托卡马克中Alfvén光谱的数值模拟结果进行比较。讨论了进一步使用DBS方法研究环形装置中Alfvén振动的前景。发现它们对应于不同的环形模式编号。通常，可以将获得的数据与Globus-M托卡马克中Alfvén光谱的数值模拟结果进行比较。讨论了进一步使用DBS方法研究环形装置中Alfvén振动的前景。