Investigation of the composition of solar and interstellar matter using solar wind and pickup ion measurements with SWICS and SWIMS on the ACE spacecraft

The Solar Wind Ion Composition Spectrometer (SWICS) and the Solar Wind Ions Mass Spectrometer (SWIMS) on ACE are instruments optimized for measurement s of the chemical and isotopic composition of solar and interstellar matter . SWICS determines uniquely the chemical and ionic-charge composition of th e solar wind, the thermal and mean speeds of all major solar wind ions from H through Fe at all solar wind speeds above 300 km s(-1) (protons) and 170 km s(-1) (Fe+16), and resolves H and He isotopes of both solar and interst ellar sources. SWIGS will measure the distribution functions of both the in terstellar cloud and dust cloud pickup ions up to energies of 100 keV e(-1) . SWIMS will measure the chemical, isotopic and charge state composition of the solar wind for every element between He and Ni. Each of the two instru ments uses electrostatic analysis followed by a time-of-flight and, as requ ired, an energy measurement. The observations made with SWICS and SWIMS wil l make valuable contributions to the ISTP objectives by providing informati on regarding the composition and energy distribution of matter entering the magnetosphere. In addition, SWIGS and SWIMS results will have an impact on many areas of solar and heliospheric physics, in particular providing impo rtant and unique information on: (i) conditions and processes in the region of the corona where the solar wind is accelerated; (ii) the locatior of th e source regions of the solar wind in the corona; (iii) coronal heating pro cesses; (iv) the extent and causes of variations in the composition of the solar atmosphere; (v) plasma processes in the solar wind; (vi) the accelera tion of particles in the solar wind; (vii) the physics of the pickup proces s of interstellar He in the solar wind; and (viii) the spatial distribution and characteristics of sources of neutral matter in the inner heliosphere.