Study of Damping of Ion Acoustic Waves in Two-Electron Temperature Plasma
Plasmas having more than one electron group with different temperatures and densities are frequently observed in laboratories as well as in space environment. The characteristics of this type of plasmas are found to be different than that of a normal electron-ion plasma. Such a plasma containing two electron populations with two distinct temperatures is produced by adopting the method of diffusion. A cylindrical stainless steel chamber is used for plasma production where two magnetic cages of varied surface field strength are employed for plasma confinement. Plasmas are individually produced using filamentary discharge mechanism inside the cages and are allowed to diffuse in the middle of the chamber. The production method is reasonably simple and gives a good control over the plasma parameters. An Ion Acoustic Wave (IAW) is launched in the plasma using a stainless steel mesh grid of 40% transparency. The wave is detected by a planar Langmuir probe. It is found that the wave suffers damping while travelling through the plasma. The damped wave amplitude with respect to propagation distance is measured. An analytical treatment of wave damping is also carried out and the outcomes of the theoretical calculations have been compared with the experimental findings. It is observed that presence of energetic electrons has a noteworthy contribution on the damping of IAW.
