Direct Observational Evidence of the Simultaneous Excitation of Electromagnetic Ion Cyclotron Waves and Magnetosonic Waves by an Anisotropic Proton Ring Distribution

<p>Magnetosonic (MS) waves and electromagnetic ion cyclotron (EMIC) waves are two important plasma wave modes in the magnetosphere. Previous simulations have shown that both waves could be generated by a ring-like proton distribution, while direct observational evidence has yet to be reported. Here, we present simultaneous observations of MS and EMIC waves and a detailed case analysis. The linear growth rates estimated for both waves are in good agreement with the observed wave frequency spectra. The measured proton distribution evolution is also compared with the simulation results, providing direct observational evidence for the previous theoretical prediction that anisotropic ring-like proton distributions could excite MS and EMIC waves simultaneously. Our findings are crucial for understanding the generation mechanisms of and relation between MS and EMIC waves and for evaluating their combined effects on energetic electron and ion dynamics. </p>

A Titanium(III) Phosphite Exhibits Polymorph-Distinct Redox Activity Involving Proton-Coupled Electron Transfer

A novel titanium(III) phosphite with intriguing polymorphism and solid-state proton-coupled electron transfer (PCET) oxidation is presented. The polymorphs show structure-dependent PCET reactivity, interpretable by proton distribution in channels. Combined with...

Proton distribution in Sc-doped BaZrO3: a solid state NMR and first principle calculations analysis

The complex local protonic distribution and proton–dopant interaction in Sc-substituted BaZrO3 was investigated by coupling solid state NMR experiments to first principle calculations.

Colliding Alfvénic wave packets in magnetohydrodynamics, Hall and kinetic simulations

The analysis of the Parker–Moffatt problem, recently revisited in Pezzi et al. (Astrophys. J., vol. 834, 2017, p. 166), is here extended by including Hall magnetohydrodynamics and two hybrid kinetic Vlasov–Maxwell numerical models. The presence of dispersive and kinetic features is studied in detail and a comparison between the two kinetic codes is also reported. Focus on the presence of non-Maxwellian signatures shows that – during the collision – regions characterized by strong temperature anisotropy are recovered and the proton distribution function displays a beam along the direction of the magnetic field, similar to some recent observations of the solar wind.