AGS-PRF: Elucidating the Channels of Energy Transport and Particle Energization in Collisionless Plasmas

Conley, Sarah A, Iowa City IA

Investigators

Abstract

Understanding the channels of collisionless energy transport in plasmas is a key step forward in the heliophysics and astrophysics turbulence communities’ goal of creating a model of collisionless plasma turbulence that can predict particle energization and acceleration rates based on parameter observations at large scales. Developing this predictive capability is critical to the ongoing efforts to create a global model of the flow of energy from the Sun, through the interplanetary medium, and out to the boundary of the heliosphere. To reach clear understanding of the channels of collisionless energy transport necessary for achieving this goal, this project will reconcile the existing collisionless energy transport models and produce a model that is consistent with both fluid and kinetic plasma theory. This post-doctoral fellowship is led by an early-career woman PI. The broader impacts include support for the PI in developing her research, outreach, and teaching capabilities. In recent years, two major models of energy transport in collisionless plasma turbulence have been suggested: a fluid model and a kinetic model. Diagnostic tools for studying each of these models for collisonless energy transfer are the Pi-D and field-particle correlation (FPC) technique, respectively. Despite rigorous theoretical footing within their respective limits (fluid and kinetic theory), the two models appear to be incompatible and it is not clear how the diagnostic techniques that have arisen from them may be used in concert. Furthermore, questions have been raised regarding the unknown consequences of these diagnostics omitting certain terms that may be important for particle energization (such as the heat flux or ballistic particle motion) and regarding the contexts (i.e. global vs. local) in which these analysis techniques are applicable. Reconciling the two models and their diagnostics is critical in order for the community to arrive at an unequivocal description of the process of collisionless energy transport and to understand the conditions where global and local methods can be used in the study of collisionless energy transport. In the heliosphere, this knowledge informs the flow of resources in both spacecraft design and simulation development. To this end, this is a timely research project that will, by resolving discrepancies between the two leading models of energy transport in collisionless plasma turbulence, (i) elucidate the channels of collisionless energy transport within the heliosphere, and (ii) clarify the use of Pi-D and the FPC technique to determine how well these methods capture system dynamics, both locally and globally. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.