Paper presented at the 5th SOHO Workshop, 17-20 June, 1997, Oslo, Norway
Coronal transport processes as well as the solar wind acceleration are basically unsolved questions in solar physics. Element and isotope composition measurements in the interplanetary medium can provide important information about the origin and the acceleration of the solar wind. The Charge, Element, Isotope Analysis System (CELIAS) on the SOHO satellite which consists of three time-of-flight spectrometers is designed to study the composition of the solar wind and of solar energetic particles. The CELIAS solar wind mass spectrometer MTOF (MASS Time-of-Flight) has a very high time- and mass resolution and is therefore an excellent tool for isotope abundance measurements. Magnesium isotope abundances cannot be modified anywhere within the Sun by conventional hydrogen burning. Therefore these isotopes provide an unique opportunity to derive constraints on fractionation effects of solar wind particles on their way from the source region in the photosphere to the interplanetary medium. We have analyzed the data of one year of operation and we will present results on the abundances of Magnesium isotopes measured in the solar wind. These results will be discussed in the context of recent theoretical models of solar wind acceleration and fractionation effects on solar wind ions.