Structural characteristics of ion holes in plasma

Abstract

Ion holes refer to the phase-space structures where the trapped ion density is lower at the center than at the rim. These structures are commonly observed in collisionless plasmas, such as the Earth’s magnetosphere. This paper investigates the role of multiple parameters in the generation and structure of ion holes. We find that the ion-to-electron temperature ratio and the background plasma distribution function of the species play a pivotal role in determining the physical plausibility of ion holes. It is found that the range of width and amplitude that defines the existence of ion holes splits into two separate domains as the ion temperature exceeds that of the electrons. Additionally, the present study reveals that the ion holes formed in a plasma with ion temperature higher than that of the electrons have a hump at its center.