LASP Science Seminars
Studying the Origin of Near-Earth Plasma
The origin of near-Earth plasma has been a topic of intense scientific study since the beginning of the space age. Earth’s magnetosphere, the magnetic cavity carved out of the solar wind by the planet’s intrinsic magnetic field, is populated by two sources. One source is the solar wind, the tenuous plasma comprised primarily of protons that is constantly blowing outward from the sun. The second source is Earth itself, where plasma flows from the ionosphere to fill the magnetosphere with protons as well as heavier ion species. Plasma of ionospheric origin is implicated in a host of magnetospheric processes with impacts on various space weather phenomena.
This presentation is divided into two main parts. The first portion will discuss recent advances in modeling ionospheric outflows of plasma and their impact on magnetospheric composition and dynamics. These advances apply an amalgam of fluid and kinetic simulation techniques, which are applied to study a number of interesting science problems. For instance, we will use numerical simulations to explore how energy inputs connect to ionospheric outflow for H+ and O+ and examine what controls the upper and lower bounds of the outflow. These results help to explore the causal physical connections underlying widely used empirical results. We will then look at the coupled space environment during a geomagnetic storm using a simulation that separates the different sources of near-Earth plasma. These simulations include separate fluids for solar wind and ionospheric protons, ionospheric oxygen, and the plasmasphere. Additionally, the model includes the effects of both a hot ring current and a cold plasmasphere population simultaneously. The second portion of the talk will discuss some of recent flight projects to address outstanding mysteries associated with ion outflow. These include the recent Endurance sounding rocket project which used atmospheric photoelectrons to measure Earth’s electric potential, and the upcoming STORIE mission to use remote sensing to explore the evolution of ring current composition.