Production and Storage of H$_{3}^{+}$ in an RF Ion Trap.

H$_{3}^{+}$ is a ubiquitous molecular ion in astrophysical plasmas and has been the subject a variety of experimental and computational studies. We have observed the production and subsequent storage of a significant H$_{3}^{+}$ population following electron bombardment of H$_2$ inside a cylindrical rf ion trap. We combined a simple time-of-flight (TOF) mass spectrometer in tandem with the trap to monitor the temporal evolution of an H$_{3}^{+}$ population as H$_{2}^{+}$ exothermically reacts with H$_2$ after the electron impact interval. At precisely determined times following electron impact, the stored ions are extracted from the trap into an 82- cm flight path terminated by an active-film detector. A 200-MHz digital oscilloscope records the TOF spectrum by monitoring the detector's current output through a 1k$\Omega $ load. As charge- transfer (CT) reactions typically dominate ion losses from the trap for neutral gas pressures $\ge \ 10^{-8}$~Torr, an analysis of the TOF spectra as a function of the delay time until the extraction pulse will yield the production and loss rate of H$_ {3}^{+}$ at a given pressure. A discussion of the apparatus, data associated with the reaction H$_{2}^{+}$ + H$_2$ $\rightarrow $ H$_{3}^{+}$ + H, and a plan for measuring CT rate coefficients between H$_{3}^{+}$ and various neutral target molecules will be presented.