  Cold (eV) ions of ionospheric origin are a major source of magnetospheric
plasma. These ions dominate the number density for most of the volume of the
magnetosphere, most of the time. This affects large-scale physics, including
plasma temperature and pressure (and thus instability thresholds) and the
Alfv\'en velocity (and thus energy transport with waves and the magnetic
reconnection rate). This also affects small-scale kinetic plasma physics,
including wave generation and the Hall physics of reconnection. Ions escaping
from the ionosphere also represent a significant fraction of the mass outflow
from planet Earth.
