Study of wave-particle interaction in the disturbed magnetosphere

Abstract

Doppler-shifted cyclotron resonance interaction between whistler mode wave and counter streaming energetic electrons has been invoked to explain whistler triggered emissions recorded at low latitude station Varanasi (Geomagnetic latitude 14°55<i>'</i>, <i>L </i>= 1.07) during moderate magnetic storm activity (Σ<i>K</i>_P= 28¯, <i>K</i>_P index varies from 4^- to 4⁺ during the observation period) on 28 Feb, 1993. The mechanism of generation of triggered emissions is briefly discussed. Parallel resonance energy of participating electrons under normal and disturbed magnetospheric conditions have been evaluated, which is found to decrease with increase in <i>L</i>-value and wave frequency. Applying a simplified approach we have estimated the interaction length, wave magnetic field and transverse resonant current, which are found to increase during the disturbed magnetospheric conditions. However, the number of energetic electrons participating in resonance process under normal and disturbed magnetosphere remains approximately the same.