Abstract
Recurrent bursting energetic-particle modes (EPMs) are observed in an l = 2 helical plasma heated by second harmonic electron cyclotron resonance heating (ECRH) without neutral beam injection. The observed instabilities are characterized by a rapid frequency downshift, propagating in the ion-diamagnetic drift direction. Such bursting MHD instabilities are seen only in fairly low-density plasmas with off-axis second harmonic ECRH. A soft x-ray detector operating in the counting mode indicates that there exist suprathermal electrons in low-density ECRH plasmas where EPMs are destabilized. The excitation of EPMs is supposed to be due to the helically trapped suprathermal electrons produced by the second harmonic ECRH.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
