EPJ Web of Conferences (Jan 2019)

Numerical description of mode coupled waves in inhomogeneous magnetized plasmas

  • Yanagihara Kota,
  • Kubo Shin,
  • Tsujimura Toru

DOI
https://doi.org/10.1051/epjconf/201920301011
Journal volume & issue
Vol. 203
p. 01011

Abstract

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Geometrical optics (GO) ray tracing has been widely used for a description of electron cyclotron resonance waves in inhomogeneous magnetized fusion plasmas. However, this reduced approach is not correct in sufficient low density plasmas with a sheared magnetic field, where mode coupling between two electromagnetic-like cold plasma modes can occur. Here, we extend a ray tracing method based on the first-order theory of extended geometrical optics (XGO), which captures mode coupled complex amplitude between O and X mode along the ray trajectory. In our approach, reference ray is calculated with ray equation to satisfy the lowest-order part of XGO theory and an evolution of complex amplitude profile along the reference ray is calculated with partial differential equation derived from first-order terms. Calculation results performed by extended ray tracing are in good agreement with 1D full wave analysis. By introducing second-order terms into our numerical approach, diffraction will be treated.