Analysis of O7+/O6+ observations in the solar wind

The ratio of O/sup 7 +//O/sup 6 +/ in the solar wind can be used to deduce the temperature at the point in the corona where the charge states become ''frozen'' in the flow, and its determination therefore depends both upon the characteristics of the instrument and those of the source. The apparent increase of the ratio O/sup 7 +//O/sup 6 +/ observed in the solar wind by K. W. Ogilvie and C. Vogt (1980) at speeds above 450 km s/sup -1/ has been reevaluated using ta gretly expanded data set. The ratio observed for solar wind speeds less than 450 km s/sup -1/ corresponds to an electron temperature of 1.7 +- 0.2 x 10/sup 60/K in the region of ''freezing in'' of th flow, as was previously reported. At higher speeds, when the kinetic temperature of the solar wind often exceeds 2--3 x 10/sup 50/K, instrumental effects become large and corrections difficult to determine.