Independent excitation of inhomogeneous energy density driven instability by electron density gradient

Abstract

In this work, we report an experimental observation of the inhomogeneous energy density driven instability (IEDDI) independently excited by the electron density gradient. This was achieved using a novel design which could generate a controllable electron density gradient, while the self-consistent electric field accompanied with the electron density gradient can be simultaneously compensated. Broadband wave mode in the ion cyclotron frequency range was excited, which was further experimentally identified as the IEDDI. This result suggests that the IEDDI can be independently excited by the electron density gradient, which could be extended to explain the satellite observations of the broadband extremely low frequency waves in the auroral plasmas where the strong plasma density inhomogeneities exist.