Empirical evidence for extended cyclotron wave heating in the solar wind by Dr. Trevor Bowen
Circularly polarized waves have been proposed as a mechanism to couple electromagnetic fluctuations to ion gyromotion, enabling ion-scale dissipation that results in observed ion-scale steepening. Here, we study Parker Solar Probe observations of an extended stream of fast solar wind ranging from ∼ 15R⊙ − 55R⊙. We demonstrate that, throughout the stream, transition-range steepening at ion-scales is associated with the presence of significant left-handed ion-kinetic scale waves, which are thought to be ion-cyclotron waves. We implement quasilinear theory to compute the rate at which ions are heated via cyclotron resonance with the observed circularly polarized waves given the empirically measured proton distribution functions. We explore the effects associated with using non parametric approximations to the VDFs and additionally report on advancements in machine learning techniques to understand the generation of these waves.