  The effects of kinetic whistler-wave instabilities on the runaway-electron
(RE) avalanche is investigated. With parameters from DIII-D experiments, we
show that RE scattering from excited whistler waves can explain several poorly
understood experimental results seen in a variety of tokamaks. We find an
increase of the avalanche growth rate and threshold electric field, bringing
the present model much closer to observations than previous results. The
excitation of kinetic instabilities and the scattering of resonant electrons
are calculated self-consistently using a quasilinear model. We also explain the
observed fast growth of electron cyclotron emission (ECE) signals and
excitation of very low-frequency whistler modes observed in the quiescent RE
experiments at DIII-D [D. A. Spong et al., submitted to Phys. Rev. Lett.].
These results indicate that by controlling the background thermal plasma
temperature, the plasma wave can be excited spontaneously in tokamak
disruptions and the avalanche generation of runaway electrons may be
suppressed.

Plasma Physics