Whitepaper #228 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: basic research. Additional topics: fundamental space plasma theory; solar physics; space-based missions/projects.
We describe a qualitatively new effect recently identified in solar physics and astrophysics, that of ion-neutral separation in the chromosphere caused by the ponderomotive force associated with Alfven and fast mode waves. We argue that these abundance anomalies are a promising route to understanding solar atmospheric waves, and hence many facets of solar activity and plasma energization.