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Resolving Terms of Vlasov's Equation with MMS
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  • Jason Shuster,
  • Daniel Gershman,
  • John Dorelli,
  • Shan Wang,
  • Naoki Bessho,
  • Li-Jen Chen,
  • Daniel da Silva,
  • Barbara Giles,
  • William Paterson
Jason Shuster
University of Maryland, College Park

Corresponding Author:jrf63@wildcats.unh.edu

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Daniel Gershman
NASA Goddard Space Flight Center
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John Dorelli
NASA Goddard Space Flight Center
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Shan Wang
University of Maryland, College Park
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Naoki Bessho
University of Maryland, College Park
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Li-Jen Chen
NASA Goddard Space Flight Center
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Daniel da Silva
Trident Vantage Systems
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Barbara Giles
NASA Goddard Space Flight Center
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William Paterson
NASA Goddard Space Flight Center
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Abstract

The unprecedented spatiotemporal resolution of the sixty-four dual electron and ion spectrometers comprising the Fast Plasma Investigation (FPI) onboard the four Magnetospheric Multiscale (MMS) spacecraft enables us to compute terms of the Vlasov equation and thus compare MMS measurements directly to kinetic theory. Here we discuss our techniques for determining spatial and velocity-space gradients of the ion and electron distribution function from the skymaps provided by FPI. We present initial results validating and comparing the contributions from ∂f/∂t, v·∇f, and a·∇vf for a variety of kinetic plasma contexts including both reconnection and non-reconnection events, such as electron diffusion regions (EDRs), magnetic holes, and thin electron-scale current sheets. The ability to resolve gradients of the distribution function motivates comparison of MMS observations to predictions from gyro-kinetic theory and particle-in-cell (PIC) simulations as an approach for determining which physical mechanism is responsible for generating ion and electron crescent distributions observed in association with EDRs and thin boundary layers.