Plasma properties in coronal holes derived from measurements of minor ion spectral lines and polarized white light intensity

Recent observations of the Ly alpha lambda 1216, Mg x lambda 625, and O VI lambda 1038 spectral lines carried out with the Ultraviolet Coronagraph Spe ctrometer (UVCS) on board SOHO at distances in the range 1.35-2.1 R-s in th e northern coronal hole are used to place limits on the turbulent wave moti ons of the background plasma and the thermal motions of the protons and Mg9 and O+5 ions. Limits on the turbulent wave motion are estimated from the measured line widths and electron densities derived from white light corona graph observations, assuming WKB approximation at radial distances-covered by the observations. It is shown that the contribution of the turbulent wav e motion to the widths of the measured spectral lines is small compared to thermal broadening. The observations show that the proton temperature slowl y increases between 1.35 and 2.7 R-s and does not exceed 3 x 10(6) K in tha t region. The temperature of the minor ions exceeds the proton temperature at all distances, but the temperatures are neither mass proportional nor ma ss-to -charge proportional. It is shown, for the first time, that collision times between protons and minor ions are small compared to the solar wind expansion times in the inner corona. At 1.35 R-s the expansion time exceeds the proton Mg+9 collision time by more than an order of magnitude. Neverth eless, the temperature of the Mg ions is significantly larger than the prot on temperature, which indicates that the heating mechanism has to act on ti mescales faster than minutes. When the expansion time starts to exceed the collision times a rapid increase of the O+5 ion spectral line width is seen . This indicates that the heavier and hotter ions lose energy to the proton s as long as collision frequencies are high, and that the ion spectral line width increases rapidly as soon as this energy loss stops.