Unexpected observations by the MMS/feeps sensors of multiple dispersive energetic electron signatures [fennell ET AL., 2016] highlighted the existence of "microinjections". That is, electrons…

This federal contract award is a $495,000 grant for research from the National Aeronautics and Space Administration (NASA) to The Aerospace Corporation, a federally funded research and development center. The research aims to characterize electron microinjections observed by the MMS/FEEPS sensors and use modeling to understand their generation, source regions, and role in energizing the outer radiation belt. This work directly supports NASA's goals of understanding magnetosphere-ionosphere coupling and boundary processes, and aligns with the National Academies' decadal survey objectives related to the dynamics of the Earth's magnetosphere. There is no set-aside designation for this contract, which has a performance period ending on September 30, 2022.

Unexpected observations by the MMS/feeps sensors of multiple dispersive energetic electron signatures [fennell ET AL., 2016] highlighted the existence of "microinjections". That is, electrons organized into clusters of temporal elements where the highest energy electrons are observed first followed by ever lower energy electrons until they map out energy versus time profiles reminiscent of classic substorm injections but on a much shorter time scale and usually repetitive. They occurred in the midnight to dusk local time sector above ~8 RE geocentric. An intriguing feature was that the microinjection electrons were dominantly field aligned. The dispersive nature of the electrons led fennell ET AL. [2016] to argue that their injection had occurred far from the observation point and that they gradient-curvature drifted to the MMS fleet. Drift tracings indicated that they were generated near the magnetopause boundary sunward of dusk and might be associated with kelvin-helmholtz instabilities, ULF waves, or flux transfer events. IT was also speculated that these microinjections might play a role in the development of the seed electron population that is ultimately accelerated to higher energies to make up the outer zone radiation belt. From those initial observations, one could not determine key features of the process, namely: how the electron microinjections were generated, where they were generated, and why they were field aligned. Microinjections have a variable range of energy-time signatures. Within microinjection clusters one often observes that their temporal profiles can cross each other, indicating they drifted different distances. This implies there can be more than one source region active at the same time or that the source region itself is moving as IT "throws off" multiple electron injections. Some microinjections have a double peaked spectrum which disperses in time. These might be overlapping injections or injections of a source population that already had a spectral peak. In addition, the repetition rate of microinjections in a cluster does not appear to be constant. The observations suggest there are intervals where the time between microinjections is shorter or longer with the slower repetition rate being up to twice as long as the average for a cluster. All such features must be related to the generation process. Thus, we propose the following investigations. 1. We will analyze the complete set of microinjections obtained by MMS from july 2015 through NOV. 2017. We will characterize their spatial-temporal features and the conditions in the interplanetary medium and inside the magnetosphere when they occurred. 2. We will use drift calculations in field models to infer where these microinjection populations came from and where they go after passing the MMS satellites. We can then check other observations like those from van allen probes, goes, geotail and themis to help define the source population and help determine if the microinjections maintain their identity as they drift beyond MMS. 3. We will use the information gained to unravel the generation process or processes, using models to investigate the physics and to pinpoint their source region(s). For example, we will trace particles through the fields from global MHD and rcme models to infer the energy changes and particle organization by the kelvin-helmholtz activity, ULF waves, and flux transfer events they predict. These studies directly support the MMS goal of understanding the role reconnection and boundary processes play in the transport and energization of the plasma across the magnetopause and within the outer magnetosphere. In addition, the studies contribute directly to the decadal survey's goals of determining the dynamics and coupling of the earth's magnetosphere and ionosphere in relation to the solar terrestrial inputs and characterizing what may be a ubiquitous process that occurs throughout the universe at magnetized planets.