We report electrostatic Debye-scale turbulence developing within the diffusion region of asymmetric magnetopause reconnection with moderate guide field using observations by the Magnetospheric Multiscale (MMS) mission. We show that Buneman waves and beam modes cause efficient and fast thermalization of the reconnection electron jet by irreversible phase mixing, during which the jet kinetic energy is transferred into thermal energy. Our results show that the reconnection diffusion region in the presence of a moderate guide field is highly turbulent, and that electrostatic turbulence plays an important role in electron heating. arXiv:1908.09724v1 [physics.space-ph]

The Earth's bow shock is the most accessible natural laboratory for in-situ analysis of various plasma processes in supercritical collisionless shock waves (e.g., Krasnoselskikh et al., 2013). One of the problems not entirely resolved in the physics of collisionless shocks concerns mechanisms of electron heating and thermalization (e.g.,

The first radial alignment between Parker Solar Probe and Solar Orbiter spacecraft is used to investigate the evolution of solar wind turbulence in the inner heliosphere. Assuming ballistic propagation, two 1.5 hr intervals are tentatively identified as providing measurements of the same plasma parcels traveling from 0.1 to 1 au. Using magnetic field measurements from both spacecraft, the properties of turbulence in the two intervals are assessed. Magnetic spectral density, flatness, and high-order moment scaling laws are calculated. The Hilbert–Huang transform is additionally used to mitigate short sample and poor stationarity effects. Results show that the plasma evolves from a highly Alfvénic, less-developed turbulence state near the Sun, to fully developed and intermittent turbulence at 1 au. These observations provide strong evidence for the radial evolution of solar wind turbulence.

Electron holes (EHs) are nonlinear electrostatic structures in plasmas. Most previous in situ studies of EHs have been limited to single‐ and two‐spacecraft methods. We present statistics of EHs observed by Magnetospheric Multiscale on the magnetospheric side of the magnetopause during October 2016 when the spacecraft separation was around 6 km. Each EH is observed by all four spacecraft, allowing EH properties to be determined with unprecedented accuracy. We find that the parallel length scale, l∥, scales with the Debye length. The EHs can be separated into three groups of speed and potential based on their coupling to ions. We present a method for calculating the perpendicular length scale, l⊥. The method can be applied to a small subset of the observed EHs for which we find shapes ranging from almost spherical to more oblate. For the remaining EHs we use statistical arguments to find l⊥/l∥≈5, implying dominance of oblate EHs.