Loss cone instability in an external high frequency electric field

Loss Cone Instability in an external high frequency electric field is investigated theoretically and the dispersion relation is derived by the Aliev and Silin method. It is proved that Loss Cone Instability at the frequency near nω_ci can be stabilized by the external high frequency electric field, if the frequency of the applied electric field is off-resonant from the ion cyclotron frequency and its harmonics, where n is the harmonic number and ω_ci is the ion cyclotron frequency. A new growing wave near l ω_o + nω_ci may exist, where l is the wave can also be stabilized to a certain degree by the stronger electric field. These results are consistent with the experimental results of PHOENIX and HX qualitatively. (author)