Localized parallel electric fields associated with inertial Alfvén waves

Measurements of intense, localized parallel electric fields are reported in association with inertial Alfvén waves and accelerated electron fluxes in a space plasma. The parallel electric fields are localized to several hundreds of Debye lengths and carry potentials on the order of the energy of the accelerated electron fluxes. The structures are observed at sharp maxima or minima of the perturbation magnetic field of the Alfvén wave, indicating high shear or rapid changes in the parallel current but near-zero, large-scale parallel currents. The localized electric-field structures are not entirely consistent with published double-layer models or observations in the aurora and may represent a new class of parallel electric-field structures or double layer, which are an important feature of the nonlinear evolution of Alfvén waves and of the electron acceleration processes. These data also represent a possible example of cross-scale coupling from Alfvén wavelengths to Debye scales.