Anomalous Doppler Resonance of Relativistic Electrons with Lower Hybrid Waves Launched in the Frascati Tokamak

Relativistic runaway electrons are detected by hard-x-ray and (photo)neutron emissions in low-density experiments with lower hybrid waves. During the rf pulse these signals can be explained in terms of the anomalous Doppler resonance on the primary lower hybrid waves which is effective on electrons having energy > 10 MeV. This effect is present independently of the density limit which determines the efficiency of the other resonance $\omega =k_{\parallel }{v}_{\parallel }$; the latter is responsible for electron tail enhancement (up to 300 keV) and for wave absorption, heating, and current-drive effects.