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Abstract Semi‐empirical coefficients for electron transport in Alfvénic turbulence are used to drive the global evolution of energetic electron distributions through Earth's outer radiation belt. It is shown how these turbulent fields facilitate radial transport and pitch‐angle scattering that drive losses through the magnetopause, into the plasma sheet, through the plasmapause and to the atmosphere. Butterfly distributions are formed due to pitch‐angle scattering and the combined effect of the loss processes. For the observed spectrum of oscillations, it is estimated that Alfvénic turbulence drives order of magnitude depletions of outer radiation belt electron fluxes at relativistic energies over a period of a few hours. On the other hand, at lower energies, energization in transverse Alfvénic electric fields leads to enhancements of the electron spectrum to provide a source population for subsequent acceleration to higher energies and, in concert with the loss processes, provides exponential spectral form as a function of energy. 

Abstract A statistical survey using 3 years of Van Allen Probes data from 2013 to 2015 is conducted to investigate the impact of broadband kinetic Alfvén waves (KAWs) on the pitch angle distributions (PADs) of relativistic electrons. 62 events exhibiting distinct KAW signatures, identified when other wave modes known to generate butterfly distributions were absent, are examined along with the corresponding PADs of electrons. The results reveal a relationship between the spectral energy density of KAWs and PAD of relativistic electrons, with butterfly PAD features becoming more pronounced and showing larger dip‐sizes as the spectral energy density of KAWs increases, particularly for electrons in 0.5–3.4 MeV energy range. At these times the magnetopause sub‐solar stand‐off distance renders magnetopause shadowing an unlikely formation mechanism. This suggests the interaction of relativistic electrons with broadband KAWs could be a significant mechanism, alongside drift‐shell splitting, contributing to the formation of butterfly PADs in the night‐side outer radiation belt of Earth. 

Abstract The transport of energetic electrons immersed in Alfvénic turbulence in Earth's outer radiation belt is explored. It is shown how electrons subject to the action of an empirically derived 3‐D spectrum of Alfvénic field fluctuations experience rapid transport acrossL‐shells, pitch‐angle and through momentum space. Timescales for radial transport are less than a drift period while scattering at large pitch‐angle occurs at a similar rate. Transport through momentum space occurs at a rate comparable to that in whistler mode chorus and is particularly rapid below 100 keV. Bounce‐averaged transport coefficients for these processes are consistent with quasi‐linear estimates for drift‐bounce resonances, albeit with enhanced values. A super‐diffusive to sub‐diffusive transition with increasing energy is identified. 

Abstract The Van Allen Probes Electric Fields and Waves (EFW) instrument provided measurements of electric fields and spacecraft floating potentials over a wide dynamic range from DC to 6.5 kHz near the equatorial plane of the inner magnetosphere between 600 km altitude and 5.8 Re geocentric distance from October 2012 to November 2019. The two identical instruments provided data to investigate the quasi-static and low frequency fields that drive large-scale convection, waves induced by interplanetary shock impacts that result in rapid relativistic particle energization, ultra-low frequency (ULF) MHD waves which can drive radial diffusion, and higher frequency wave fields and time domain structures that provide particle pitch angle scattering and energization. In addition, measurements of the spacecraft potential provided a density estimate in cold plasmas ( $$<20~\text{eV}$$ < 20 eV ) from 10 to $$3000~\text{cm}^{-3}$$ 3000 cm − 3 . The EFW instrument provided analog electric field signals to EMFISIS for wave analysis, and it received 3d analog signals from the EMFISIS search coil sensors for inclusion in high time resolution waveform data. The electric fields and potentials were measured by current-biased spherical sensors deployed at the end of four 50 m booms in the spacecraft spin plane (spin period $$\sim11~\text{sec}$$ ∼ 11 sec ) and a pair of stacer booms with a total tip-tip separation of 15 m along the spin axis. Survey waveform measurements at 16 and/or 32 S/sec (with a nominal uncertainty of 0.3 mV/m over the prime mission) were available continuously while burst waveform captures at up to 16,384 S/sec provided high frequency waveforms. This post-mission paper provides the reader with information useful for accessing, understanding and using EFW data. Selected science results are discussed and used to highlight instrument capabilities. Science quantities, data quality and error sources, and analysis routines are documented.