Experimental Observation of Electron-Acoustic Wave Propagation in Laboratory Plasma

Abstract

In the field of fundamental plasma waves, direct observation of electron-acoustic wave (EAW) propagation in laboratory plasmas remains a challenging problem, mainly because of heavy damping. In the MaPLE device, the wave is observed and seen to propagate with phase velocity $\sim 1.8$ times the electron thermal velocity. A small amount of cold, drifting electrons, with moderate bulk to cold temperature ratio ($\approx 2-3$), is present in the device. It plays a crucial role in reducing the damping. Our calculation reveals that the drift relaxes the stringent condition on the temperature ratio for wave destabilization. Growth rate becomes positive above a certain drift velocity even if the temperature ratio is moderate. The observed phase velocity agrees well with the theoretical estimate. Experimental realization of the mode may open up a new avenue in EAW research.

6 pages, 9 figures

Cited by in corpus (2)

• The electron acoustic waves in plasmas with two kappa-distributed electrons at the same temperatures and immobile ions
• Landau damping of electron-acoustic waves due to multi-plasmon resonances