Numerical description of mode coupled waves in inhomogeneous magnetized plasmas

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 sucient low density plasmas with a sheared magnetic eld, where mode coupling between two electromagnetic-like cold plasma modes can occur. Here, we extend a ray tracing method based on the rst-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 prole along the reference ray is calculated with partial dierential equation derived from rst-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, diraction will be treated.