Chorus Waves and Spacecraft Potential Fluctuations: Evidence for Wave-Driven Enhanced Photoelectron Escape

The amplitude and spatial distribution of chorus waves in the radiation belts and inner magnetosphere directly influence their ability to drive both electron energization and loss. For over a decade, observed correspondence between spacecraft potential fluctuations, interpreted as plasma density structure, and chorus waves has helped guide theoretical understanding of chorus wave amplitudes and spatial distributions. This work uses data from the Van Allen Probes to demonstrate that the spacecraft potential fluctuations observed to coincide with many chorus waves are not due to true plasma density structure, but are instead consistent with enhanced photoelectron escape driven by chorus wave electric fields. In addition to Van Allen Probes data analysis, recent simulation and laboratory studies support the interpretation that spacecraft potential fluctuations can be driven by enhanced photoelectron loss due to wave electric fields. These results suggest that theoretical understanding of chorus waves based upon the correspondence between wave amplitude and spacecraft potential fluctuations should be reexamined.