The role of low density upflowing field-aligned electron beams (FEBs) on the growth rate of the electron cyclotron waves at the frequencies ω r 1.5 keV) have been found to have significant effect on the growth rate. Analysis has revealed that it is mainly the T ‖b which inhibits the growth rate (magnitude) and the range of frequency (bandwidth) of the instability mainly in the higher frequency spectrum. The inhibition in the growth rate and bandwidth increases with increase in T ‖b. The FEBs with less E b (giving drift velocity) reduce growth rate more than the beams with larger E b. The inhibition of growth rate increases with the increase in the ratio ω e/Ωe indicating that the beams are more effective at higher altitudes
