Harmonics of electrostatic ion cyclotron waves in three component magnetised plasma
Abstract
Electrostatic ion cyclotron (EIC) waves and their instability (electrostatic ion cyclotron instability- EICI) have been observed in various regions of magnetosphere, by various satellites, e.g., Cluster, FAST and THEMIS, as well as in laboratory plasmas. EIC waves propagate nearly perpendicular to ambient magnetic field, with a small finite wave number along ambient magnetic field. EIC waves have gained importance as they provide perpendicular heating of the ions in the magnetosphere. EICI pertaining to the higher harmonics of proton and Helium cyclotron modes is investigated in a three-component magnetized plasma consisting of beam electrons, protons and doubly charged Helium ions. Fewer harmonics of proton cyclotron waves with decreased growth rates and higher number of Helium harmonics with decreased growth rates can be seen with increase in the angle of propagation. Except for one particular case where second harmonic also become unstable, in most of the scenario only odd Helium harmonics are excited. The growth rate of the instabilities enhances with the increase in number density of ions, however, temperature of ions has adverse effect on the growth rate. In addition to this, as the electron beam speed is increased, the number of harmonics as well as peak growth rate increases. Our results are relevant to laboratory and space plasmas where field-aligned currents exist.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E3320S