Plasma Wave Phase Analysis of the Magnetosphere-Multiscale Fast Plasma Investigation Data
Abstract
Plasma waves are characterized by the back and forth flow of wave energy between electric and magnetic fields and the charged particles that comprise the wave mode. If the plasma density is tenuous like in the magnetotail or if the wave amplitude is small, the wave might not be easily detected by the Fast Plasma Investigation (FPI) in either the phase space density (PSD) or its moments. There are many examples where nearly monochromatic coherent waves are observed in the magnetic and electric fields data at frequencies below the Nyquist Frequency of FPI (16.7 Hz for electrons, 3.3 Hz for ions) but not detected by FPI. Each PSD pixel is sampled for ~195/1000 μs plus a 39/171 μs settling time during the 0.030/0.150 s PSD sweep time of the electrons/ions. By time tagging each individual PSD pixel with its time of its measurement, each individual measurement can be assigned a phase associated with the waves. Over many wave cycles this allows us to bin the FPI measurements into phase bins and thereby increase the signal to noise. In this study, using this approach, we will attempt to reconstruct the signature in the FPI data of coherent wavesbelow the FPI Nyquist frequency, for ion Bernstein mode waves in the plasmasheet/boundary layer, compressional fast magnetosonic waves in the dayside magnetosphere, magnetospheric ion cyclotron waves, and low frequency magnetospheric whistler waves. We will discuss the theoretical signatures of plasma waves in ion and electron distributions, then we will discuss the time tagging of individual FPI PSD measurements, and lastly show examples where we attempted to recover the wave signature in the FPI data.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSM51H3253B
- Keywords:
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- 2730 Magnetosphere: inner;
- MAGNETOSPHERIC PHYSICS;
- 2752 MHD waves and instabilities;
- MAGNETOSPHERIC PHYSICS;
- 2772 Plasma waves and instabilities;
- MAGNETOSPHERIC PHYSICS;
- 2774 Radiation belts;
- MAGNETOSPHERIC PHYSICS