GENERATION MECHANISM OF MAGNETIC NOISE BURSTS IN THE EARTHS MAGNETOTAIL

In this paper, we study the electromagnetic instability driven by ion beams and plasma inhomogeneity in the plasma sheet boundary layer and for the first time obtain the growth rate spectrum of electromagnetic waves in a broad frequency range (OMEGA(i) << 0.1-omega(LH) less-than-or-similar-to\omega(r)\ less-than-or-equal-to OMEGA(e), OMEGA(i) and OMEGA(e) are respectively the ion and electron cyclotron frequencies, omega(LH) = (OMEGA(i)OMEGA(e))1/2 is the lower hybrid frequency). The peak of the growth rate spectrum is near \omega(r)\ almost-equal-to omega(LH) and the second peak is near \omega(r)\ less-than-or-similar-to OMEGA(e). The fundamental characteristics of the growth rate spectrum are in agreement with the satellite observations of the magnetic noise bursts in the magnetotail.