@article{8793,
  author = {J. Smoniewski and E. Sanchez and I. Calvo and M.J. Pueschel and J.N. Talmadge},
  title = {Comparison of local and global gyrokinetic calculations of collisionless zonal flow damping in quasi-symmetric stellarators},
  abstract = {The linear collisionless damping of zonal flows is calculated for quasi-symmetric stellarator equilibria in flux-tube, flux-surface, and fullvolume geometry. Equilibria are studied from the quasi-helical symmetry configuration of the Helically Symmetric eXperiment (HSX), a broken symmetry configuration of HSX, and the quasi-axial symmetry geometry of the National Compact Stellarator eXperiment (NCSX).
Zonal flow oscillations and long-time damping affect the zonal flow evolution, and the zonal flow residual goes to zero for small radial wavenumber. The oscillation frequency and damping rate depend on the bounce-averaged radial particle drift in accordance with theory. While each flux tube on a flux surface is unique, several different flux tubes in HSX or NCSX can reproduce the zonal flow damping from a flux-surface calculation given an adequate parallel extent. The flux-surface or flux-tube calculations can accurately reproduce the full-volume long-time residual for moderate k x, but the oscillation and damping time scales are longer in local representations, particularly for small k x approaching the system size.},
  year = {2021},
  journal = {Physics of Plasmas},
  volume = {28},
  pages = {042503},
  doi = {10.1063/5.0038841},
  language = {eng},
}