Speaker: Meers Oppenheim, Boston University, Astronomy Department
Abstract: All planetary atmospheres have a region where solar radiation ionizes the air, creating an ionosphere; a plasma extending from the upper atmosphere to the space environment. For the Earth, the ionosphere extends from 80 km above the ground, where neutrals outnumber ions by over 8 orders of magnitude, to around 1000 km, where ions and neutrals have similar numbers. This region absorbs the majority of EUV and X-rays from the Sun. Energetic particles from the magnetosphere, the solar wind, and the cosmos slam into it. Billions of meteors deposit tons of materials in it, daily. From below, winds and turbulence in the Earth’s atmosphere push it around. All these interactions make the ionosphere complex and interesting. NASA and the space community need accurate models of the ionosphere since the International Space Station and most of our spacecraft exist within it, and can experience harmful radiation and electric charging. The ionosphere was first discovered because of its impact on radio communication and its interference with Earth to Space communications and GPS remain critical issues. This talk will present the basics of ionospheric plasma physics, present a method of simulating ionospheric plasmas, the Particle-in_Cell (PIC) method. It will then show how we used this method to study a number of turbulent processes in the ionosphere and what we have learned from these studies.