Observation of the parametric decay instability during electron cyclotron resonance heating on the Versator II tokamak

Observations are reported on a nonlinear, three-wave interaction process occurring during high-power electron cyclotron heating in the Versator II tokamak. The measured spectra and the threshold power are consistent with a model in which the incident power in the extraordinary mode of polarization decays at the upper-hybrid resonance layer into a lower-hybrid wave and an electron Bernstein wave.