Trapping of electron Bernstein waves in drift-wave eddies and parametric decay instability at second harmonic ECRH in toroidal devices

The possibility of 3D electron Bernstein wave trapping in intensive magnetic field aligned density fluctuation or blobs in toroidal plasma is demonstrated. A semi-analytic approach for the description of associated plasma cavity is developed. A mechanism of low-threshold parametric decay instability driven by extraordinary pump microwave and leading to the excitation of localized second harmonic electron Bernstein waves and low-frequency heavily damped oscillations is proposed and analysed. (paper)