الفهرس | Only 14 pages are availabe for public view |
Abstract A highly structured plasma environment, with a large number of readily available energy resources, has been revealed by the In Situ measurements in the Martian Ionosphere. The energetic growth in plasma suggests that it is not compatible with the Thermodynamic equilibrium. A wide range of plasma wave characteristics arises due to large deviations from thermodynamic equilibrium. In this way, a large number of wave modes and unstable fluctuations may be supported by the Martian plasma. The main features of fully nonlinearly low-frequency electrostatic wave modes, such as ion acoustic solitary waves and double layer waves in plasmas that are relevant to the Martian Ionosphere will be investigated by this thesis. In order to model ionospheric plasma and study how its variability affects the fundamental features of these waves, this methodology is based upon the use of hydrodynamical modeling as well as observations by Mars Atmosphere and Volatile Evolution (MAVEN). Three chapters are included in this thesis, describing them as follows: Chapter I, shows a short overview of Mars, where its typical features and plasma environment are found. Besides, a summary of the major space missions that explored it. In Chapter II, We investigated how variations in number density in plasma affect the propagation of low-frequency electrostatic waves in the planet’s ionosphere. We use a collisionless inhomogeneous unmagnetized plasma model with two positive cold ion species (O+, H+) with nonthermal electrons for this purpose. the basic equations are reduced to one evolution equation. The latter has been analyzed and solved numerically to obtain an arbitrary amplitude shock wave profle as well as the possible regions for the existing waves. We’ve put forward a negative potential, which is consistent with the compressive wave profle. An interpretation of the electrostatic waves, which can be found in Mars’ ionizing atmosphere, is based on fndings from this investigation. We’re going to be able to explain how the gas is lost from the ionosphere if we can observe this wave in Mars’ Ionosphere. In Chapter III, We investigated the propagation properties of fully ivnonlinear ion-acoustic solitary waves and double-layer waves in the Martian ionosphere. The plasma model consists of three positive ions (H+, O+, and O2+) and superthermal electron distribution. Sagdeev pseudo-potential is obtained for arbitrary amplitude ion-acoustic waves. The effects of plasma parameters on the nature of the solitary waves and double layer waves are investigated. The velocity of the wave phase has been established to be supersonic, and this is in agreement with the observations. |