Effect of upflowing field-aligned electron beams on the electron cyclotron waves in the auroral magnetosphere

Pramana

S K Singh¹  Sushil Kumar1²  A K Gwal¹ 

[1]Space Physics Laboratory, Department of Physics, Barkatullah University, Bhopal 462 026, India$$

[2]Physics Division, School of Engineering and Physics, The University of the South Pacific, Suva, Fiji$$

关键词: Field-aligned electron beams;    electron cyclotron waves;    wave-particle interaction;    auroral region.;   

DOI  :  

学科分类：物理（综合）

来源: Indian Academy of Sciences

【 摘 要 】

The role of low density upflowing field-aligned electron beams (FEBs) on the growth rate of the electron cyclotron waves at the frequencies 𝜔r < 𝛺­e, propagating downward in the direction of the Earth's magnetic field, has been analysed in the auroral region at 𝜔e/𝛺e < 1 where 𝜔e is the plasma frequency and 𝛺­e is the gyrofrequency. The FEBs with low to high energy (𝐸b) but with low temperature (𝑇∥b) have no effect on these waves. The FEBs with 𝐸b < 1 keV and 𝑇∥b (> 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 𝐸b (giving drift velocity) reduce growth rate more than the beams with larger 𝐸b. The inhibition of growth rate increases with the increase in the ratio 𝜔e/𝛺e indicating that the beams are more effective at higher altitudes.

【 授权许可】

Unknown