  Radio frequency waves are routinely used in tokamak fusion plasmas for plasma
heating, current control, and as well as in diagnostics. These waves are
excited by antenna structures placed near the tokamak's wall and they have to
propagate through a turbulent layer known as scrape-off layer, before reaching
the core plasma (which is their target). This layer exhibits coherent density
fluctuations in the form of blobs and filaments.
  The scattering processes of RF plane waves by single blob is studied, with
the assumption that the blob has cylindrical shape and infinite length. The
axis of the blob is not necessarily aligned with the externally applied
magnetic field in the case of plane waves.
  The investigation concerns the case of Electron Cyclotron (EC) waves
($f_0$=170 $GHz$) for ITER-like and Medium Size Tokamak applications (such as
TCV, ASDEX-U, DIII-D, etc) as well as the case of Low Hybrid (LH) waves
($f_0$=4.6 $GHz$) for ALCATOR C-MOD Tokamak device. The study covers for a
variety of density contrasts between the blobs and the ambient plasma and a
wide range of blob radii.

Plasma Physics