Princeton University Astroplasmas Seminar

In the weakly-collisional intracluster medium (ICM) and solar wind, the flow of energy from hydrodynamic to electron kinetic scales dictates the light and waves that we see with telescopes or with satellites in the heliosphere. We explore two mechanisms for energy flow in such plasmas.

First, in the high-beta ICM, Megaparsec-scale motions promptly trigger nanoparsec-scale plasma waves, which in turn can interact with a diffuse, long-lived "fossil" population of 1–100 MeV cosmic ray electrons (CRe). We study CRe scattering upon ion cyclotron waves driven by continuous compression in 1D particle-in-cell (PIC) simulations, which leads to energy gain by magnetic pumping. Resonant CRe gain ~10–30% of their initial energy in one compress/dilate cycle with magnetic field amplification ~3–6x, assuming adiabatic decompression without further scattering and averaging over initial pitch angle.

Second, within solar wind shocks, satellites see a zoo of electron Debye-scale structures that are not yet fully reproduced in kinetic shock simulations. We study one such class of waves—electron acoustic waves and electron holes—within the ion-scale, fast-mode wave-train precursor of a weak, low-beta shock. We'll show preliminary results on how the electron-scale wave power varies with simulation parameters.