Parker Solar Probe observations of proton beams simultaneous with ion-cyclotron waves

Identifying energy transfer mechanisms of the inner heliosphere has been an outstanding mystery for many decades. Unprecedented in-situ measurements from NASA's latest mission to the Sun, Parker Solar Probe (PSP), may shed light on an answer. The existence of non-Maxwellian ion velocity distribution functions in association with plasma wave growth (and decay) yields insight to key energy transfer mechanisms leading to solar wind thermalization. We present initial PSP observations during the second encounter within 35-50 solar radii supporting the presence of proton beams, measured by SPAN-I on the Solar Wind Electrons Alphas and Protons (SWEAP) instrument suite, associated with ion-cyclotron waves, as observed by the FIELDS instrument. Wavelet transformations applied to the magnetic field data reveal spectra approximate to the ion-cyclotron frequency. It is hypothesized that these wave modes were driven by the simultaneously measured secondary proton beams. During quiet periods where the magnetic field is radially aligned, we also show that the energy density is dominated by these waves. Further work will characterize the stability of the velocity distribution functions during the observed correlations between the proton beams and ion-cyclotron wave modes.