Parker Solar Probe Evidence for the Absence of Whistlers Close to the Sun to Scatter Strahl and to Regulate Heat Flux

Using the Parker Solar Probe FIELDS bandpass filter data and SWEAP electron from Encounters 1 through 9, we show statistical properties of narrowband whistlers ~16 Rs to ~130 Rs, compare wave occurrence including beta, temperature anisotropy heat flux. Whistlers are very rarely observed inside ~28 (~0.13 au). Outside 28 they occur within a narrow range parallel beta ~1 10, with beta-heat flux consistent whistler fan instability. Because distributions ~30 display signatures ambipolar electric field, lack suggests that modification distribution function associated field or changes in other plasma must result lower instability limits for modes (including solitary waves, ion acoustic waves) close Sun. The whistler-mode waves Sun regions either low (<.1) high (>10) is also significant understanding modeling evolution flare-accelerated electrons, regulation astrophysical settings stellar winds, interstellar medium, accretion disks, intra-galaxy cluster medium