On the possibility of nonlinear phase bunching effects in the extraordinary mode decametric radio emission of Jupiter

Electron phase bunching can become important on a millisecond time scale in coherent extraordinary mode waves of the amplitude estimated for the Jovian and terrestrial radio emissions, assuming that the emission frequency is slightly above the local cyclotron frequency. Through a coherent interaction a significant fraction of the energy of cyclotron resonant electrons can be transferred to such waves. If the in situ wave fields are sufficiently coherent, phase bunching effects may control the high-resolution dynamic spectrum of the emissions. Field gradients may prevent such phase bunching in the terrestrial magnetosphere, but not in the Jovian decametric source region. Phase-coherent theories suggest two possible explanations of the frequency drift of Jovian millisecond radio bursts. (AIP)