• DOI:10.1088/1361-6587/aa6990
• Corpus ID: 119403085

Semianalytical calculation of the zonal-flow oscillation frequency in stellarators

@article{Monreal2017SemianalyticalCO,
  title={Semianalytical calculation of the zonal-flow oscillation frequency in stellarators},
  author={P. Monreal and E. S{\'a}nchez and Iv{\'a}n Calvo and A. Bustos and Felix I. Parra and Alexey Mishchenko and Axel Konies and Ralf Kleiber},
  journal={Plasma Physics and Controlled Fusion},
  year={2017},
  volume={59}
}

• P. Monreal, E. Sánchez, +5 authors R. Kleiber
• Published 10 January 2017
• Physics
• Plasma Physics and Controlled Fusion

Due to their capability to reduce turbulent transport in magnetized plasmas, understanding the dynamics of zonal flows is an important problem in the fusion program. Since the pioneering work by Rosenbluth and Hinton in axisymmetric tokamaks, it is known that studying the linear and collisionless relaxation of zonal flow perturbations gives valuable information and physical insight. Recently, the problem has been investigated in stellarators and it has been found that in these devices the relaxation process exhibits a characteristic feature: a damped oscillation. The frequency of this oscillation might be a relevant parameter in the regulation of turbulent transport, and therefore its efficient and accurate calculation is important. Although an analytical expression can be derived for the frequency, its numerical evaluation is not simple and has not been exploited systematically so far. Here, a numerical method for its evaluation is considered, and the results are compared with those obtained by calculating the frequency from gyrokinetic simulations. This ‘semianalytical’ approach for the determination of the zonal-flow frequency is revealed to be accurate and faster than the one based on gyrokinetic simulations.