Affiliation:
1. Department of Earth and Space Sciences Southern University of Science and Technology Shenzhen China
2. Los Alamos National Laboratory Los Alamos NM USA
3. Shandong Key Laboratory of Optical Astronomy and Solar‐Terrestrial Environment School of Space Science and Physics Institute of Space Sciences Shandong University Weihai China
Abstract
AbstractLinear instability analysis as well as a corresponding two‐dimensional hybrid simulation are performed to examine the excitation of the proton cyclotron waves observed upstream of Mars. The waves are believed to be excited by the pickup ions produced from the ionization of the Martian hydrogen exosphere. And previous statistical analysis of wave observations suggested that the waves are mostly related to pickup ion beam velocity distributions. While earlier linear instability analysis of pickup ion beam distributions has mainly been focused on the parallel unstable modes, our analysis reveals that the maximum growth rate occurs at very oblique propagation. The corresponding hybrid simulation confirms the linear analysis results and further demonstrates that the pickup ions are scattered toward an isotropic shell velocity distribution by the waves excited. Interestingly, the waves at oblique propagation gradually damp out and the system is eventually dominated by waves of quasi‐parallel propagation.
Funder
Chinese Academy of Sciences
National Natural Science Foundation of China
Pearl Therapeutics
Shenzhen Graduate School, Peking University
Southern University of Science and Technology
Publisher
American Geophysical Union (AGU)
Subject
General Earth and Planetary Sciences,Geophysics