Solar wind ion composition.

The author discusses recent results on solar wind ion composition which have been obtained in three different domains: in situ measurements by spacecraft borne instruments, investigation of lunar soils for surface implanted gases, and theoretical models of solar wind generation and acceleration. The general agreement of solar wind abundances with solar energetic particle abundances is confirmed. Abundances and ionization states of different elements in the solar wind depend on the coronal temperature, on the coronal temperature gradient, and on the process which feeds ions into the solar wind. Future goals for research in the field of solar wind composition are discussed.