Statistics on Whistler Waves Propagation Direction from Parker Solar Probe Observation

Whistler waves in the solar wind are one of the candidates for regulating the solar wind heat flux and scattering of the suprathermal electron beam (conversion of the Strahl population into the halo). We investigate the whistler waves from the spectrogram data of magnetic and electric field perturbations collected continuously by the Digital Fields Board (the FIELDS suite) on board Parker Solar Probe. We develop the technique to resolve the wave propagation direction (sunward, anti-sunward, or counter-propagating) inferred from the electric and magnetic field wave power ratio $(\vert \text{Ew}\vert /\vert \text{Bw}\vert)$ and use our method to compose the database of whistler wave parameters from the continuous spectral data. We have evaluated the effective length of the PSP electric field antennas for a wide range of background plasma parameters. During Encounters 1 to 15, the cross-occurrence of sunward and anti-sunward whistlers show dependence on solar wind parameters and global reliance on the heliocentric distance. The obtained trends in whistler parameters shed light on possible wave-generation mechanisms.