Kinetic Simulations of Electron Acceleration by Dispersive Scale Alfvén Waves in Jupiter's Magnetosphere
Dispersive Alfven waves, Electron acceleration, Kinetic simulations, Jupiter, Magnetosphere
Recent observations of the Juno satellite at Jupiter illustrate that the electron energy spectrum at high latitudes is observed to be broadband—that is, ranging in energies from tens of electron volts to tens and hundreds of kiloelectron volts. At Earth, such electron spectra are associated with electron energization by Alfvén waves—which are transverse waves that travel along magnetic field lines in close analogy to waves on a string. In particular, at small scales (e.g., perpendicular scale lengths on the order of the ion orbit around the field line), kinetic effects allow for significant electric field generation that can efficiently accelerate electrons parallel to the field line. At these scales, the waves are known as dispersive Alfvén waves. In this work, we, for the first time, present global‐scale (entire dipolar field line) kinetic simulations of electron energization at Jupiter. We illustrate that these dispersive Alfvén waves, sourced in the Io plasma torus, lead to broadband electron energization close to the Jupiter ionosphere that is qualitatively consistent with the Juno observations. We additionally illustrate how the presence of the Io plasma torus (which is a feature unique to the Jupiter ionosphere) affects the characteristics of this broadband energization.
Geophysical Research Letters
Johnson, Jay R.; Damiano, P. A.; Delamere, P. A.; Stauffer, B.; and Ng, C. S., "Kinetic Simulations of Electron Acceleration by Dispersive Scale Alfvén Waves in Jupiter's Magnetosphere" (2019). Faculty Publications. 1108.