X-ray emission from collisions of O$^{7+}$ with atomic and molecular gases in the 35 to 50 KeV range.*

The solar winds are mainly comprised of protons and helium ions; however, the energetic x rays emitted from ion-comet interactions originate from the smaller fraction of heavier highly charged solar-wind ions (e.g., C, N, O, Mg, Fe ions), which have large electron-capture cross sections. One of the goals of this work is to provide high-resolution spectroscopic information for modeling of soft x-ray emission observed from solar-wind ion interactions with cometary gases. Using the JPL ECR ion source in conjunction with a grazing incidence XUV spectrometer, equipped with a CCD camera, x rays in the wavelength range from 2 to 40 nm have been measured in collisions of O$^{7+}$ with CH$_{4}$, CO, He, H$_{2}$, and H$_{2} $O gases.