Plasma Seismology: Fully Exploiting the Information Contained in Velocity Space of Kinetic Plasmas using the Morrison G Transform

TL;DR

This paper introduces Plasma Seismology, a novel technique utilizing the Morrison G Transform to invert particle velocity distribution data for reconstructing electric field variations in plasmas, demonstrated through kinetic simulations.

Contribution

The paper presents a new Plasma Seismology method that uses the Morrison G Transform to extract spatial electric field information from particle velocity data at a single point.

Findings

Standard Morrison G Transform predicts electric field evolution from all-space measurements.

Modified Morrison G Transform estimates spatial electric field variations from single-point measurements.

Technique shows promise for analyzing spacecraft data in magnetized plasmas.

Abstract

Weakly collisional plasmas contain a wealth of information about the dynamics of the plasma in the particle velocity distribution functions, yet our ability to exploit fully that information remains relatively primitive. Here we aim to present the fundamentals of a new technique denoted Plasma Seismology that aims to invert the information from measurements of the particle velocity distribution functions at a single point in space over time to enable the determination of the electric field variation over an extended spatial region. The fundamental mathematical tool at the heart of this technique is the Morrison $G$ Transform. Using kinetic numerical simulations of Langmuir waves in a Vlasov-Poisson plasma, we demonstrate the application of the standard Morrison $G$ Transform, which uses measurements of the particle velocity distribution function over all space at one time to predict the evolution of the electric field in time. Next, we introduce a modified Morrison $G$ Transform which uses measurements of the particle velocity distribution function at one point in space over time to determine the spatial variation of the electric field over an extended spatial region. We discuss the limitations of this approach, particularly for the numerically challenging case of Langmuir waves. The application of this technique to Alfven waves in a magnetized plasma holds the promise to apply the technique to existing spacecraft particle measurement instrumentation to determine the electric fields over an extended spatial region away from the spacecraft.