Electron cyclotron heating using the fundamental extraordinary mode launched from the low field side on DIII-D

Electron Cyclotron Heating experiments on the DIII‐D tokamak using outside launch of the extraordinary mode have shown effective bulk heating at the fundamental resonance, in contradiction of the theory of wave propagation. This result may be explained by an efficient process of mode conversion from the extraordinary mode to the ordinary mode upon reflection at the vessel wall of waves reflected from the right hand cutoff in the plasma. The resulting heating has the characteristics expected for heating with the ordinary mode.