Year: 2026
Type: article
Abstract: As altitude decreases in the Venusian plasma environment, the plasma density increases sharply, the magnetic field strength changes, ion temperatures decrease, and the number density of heavier ions increases. These variations strongly influence the growth and damping of O + cyclotron harmonics. The growth/damping rates of O + cyclotron harmonics are investigated in different regions of the Venusian plasma environment using a kinetic theory based dispersion relation. The magnetized plasma consists of Maxwellian electrons, protons, and heavier ions in the background, along with energetic ring-beam atomic oxygen ions. The growth rate of O + cyclotron harmonics decreases by about an order of magnitude when moving from the magnetosheath to the induced magnetosphere boundary and becomes completely damped upon reaching the upper ionosphere. The large increase in plasma density and the decrease in magnetic field strength are the main contributors to the damping observed in the upper ionosphere. Although the increase in the density of heavier ions leads to a slight increase in the growth/damping rate, this effect is much smaller compared to the reduction caused by changes in plasma density and magnetic field strength. This study explains the recently reported damped quasi-perpendicularly propagating waves with frequencies between the H + and O + gyrofrequencies in the Venusian upper ionosphere, observed by the Pioneer Venus Orbiter.
Source: The Astrophysical Journal
Authors: Amrutha, S. V. Singh, K. C. Barik, G. S. Lakhina
Language: English
Subfield: Space and Planetary Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W7167102410