From Ionospheric Electrodyamics at Mars to Mass and Momentum Loading at Saturn: Quantifying the Impact of Neutral-Plasma Interactions using Plasma Dynamic Simulations
Location
Yosemite National Park
Start Date
2-14-2014 11:00 AM
End Date
2-14-2014 11:30 AM
Description
Planetary environments provide compelling natural laboratories for exploring and quantifying the various expressions of plasma-neutral interactions in magnetospheric systems. Quantifying these interactions requires consideration of momentum and energy exchange between neutral and plasma populations, tracking of plasma sources and losses, and propagation of these effects into the generation of currents and fields. We have incorporated these interactions into a multifluid plasma dynamic modeling infrastructure in order to examine their influence in two very different planetary environments: Mars and Saturn. For Mars we consider the coupling of the neutral atmosphere to the ionospheric plasma throughout the atmospheric column and in the presence of remanent crustal magnetic fields. At altitudes where the collision frequency between charged species and neutrals becomes larger than the gyrofrequecy, these charged particles become demagnetized and follow the neutral flow. In the atmospheric dynamo region (100−250 km altitude), ions depart from the gyropath due to collisions with moving neutral particles (i.e., winds), while electron motion remains governed by electromagnetic drift. In our simulations, we track this differential motion of the ions and electrons and calculate the associated electric currents and induced perturbation field generated in the dynamo region. We also examine how the overall electromagnetic changes may ultimately alter the behavior of the local ionosphere beyond the dynamo region. At Saturn, we incorporated the same types of physical interactions into a global scale magnetospheric simulation in order to capture the interaction of the extended neutral cloud with Saturn’s rapidly rotating magnetosphere. We included an empirical representation of Saturn's neutral cloud and again modified the multifluid equations to include the collisions necessary to quantify the globally distributed mass- and momentum-loading on the system. Collision cross-sections between ions, electrons, and neutrals were calculated as functions of closure velocity and energy at each grid point and time step, enabling us to simulate the spatially and temporally varying plasma-neutral interactions. We use this updated multifluid simulation to investigate the dynamics of Saturn's magnetosphere, focusing specifically on the production of new plasma, the resulting radial outflow, interchange events, and corotation lag profiles.
From Ionospheric Electrodyamics at Mars to Mass and Momentum Loading at Saturn: Quantifying the Impact of Neutral-Plasma Interactions using Plasma Dynamic Simulations
Yosemite National Park
Planetary environments provide compelling natural laboratories for exploring and quantifying the various expressions of plasma-neutral interactions in magnetospheric systems. Quantifying these interactions requires consideration of momentum and energy exchange between neutral and plasma populations, tracking of plasma sources and losses, and propagation of these effects into the generation of currents and fields. We have incorporated these interactions into a multifluid plasma dynamic modeling infrastructure in order to examine their influence in two very different planetary environments: Mars and Saturn. For Mars we consider the coupling of the neutral atmosphere to the ionospheric plasma throughout the atmospheric column and in the presence of remanent crustal magnetic fields. At altitudes where the collision frequency between charged species and neutrals becomes larger than the gyrofrequecy, these charged particles become demagnetized and follow the neutral flow. In the atmospheric dynamo region (100−250 km altitude), ions depart from the gyropath due to collisions with moving neutral particles (i.e., winds), while electron motion remains governed by electromagnetic drift. In our simulations, we track this differential motion of the ions and electrons and calculate the associated electric currents and induced perturbation field generated in the dynamo region. We also examine how the overall electromagnetic changes may ultimately alter the behavior of the local ionosphere beyond the dynamo region. At Saturn, we incorporated the same types of physical interactions into a global scale magnetospheric simulation in order to capture the interaction of the extended neutral cloud with Saturn’s rapidly rotating magnetosphere. We included an empirical representation of Saturn's neutral cloud and again modified the multifluid equations to include the collisions necessary to quantify the globally distributed mass- and momentum-loading on the system. Collision cross-sections between ions, electrons, and neutrals were calculated as functions of closure velocity and energy at each grid point and time step, enabling us to simulate the spatially and temporally varying plasma-neutral interactions. We use this updated multifluid simulation to investigate the dynamics of Saturn's magnetosphere, focusing specifically on the production of new plasma, the resulting radial outflow, interchange events, and corotation lag profiles.