Charge Exchange and Dissociation of ${\mathrm{H}}^{+}$, ${\mathrm{H}}_2^{+}$, and ${\mathrm{H}}_3^{+}$ Ions Incident on ${\mathrm{H}}_2$ Gas

A unified set of measurements has been conducted of the yield cross sections for the various fast charged and neutral atomic particles produced in single collisions of ${\mathrm{H}}^{+}$, ${\mathrm{H}}_2^{+}$, and ${\mathrm{H}}_3^{+}$ ions with ${\mathrm{H}}_2$ gas molecules. The fast particles in question result from the dissociation or charge neutralization of the primary ions and have essentially the same velocity as the primary ions. The measurements cover the energy range from 3 to 100 keV for ${\mathrm{H}}^{+}$ primaries, 3 to 120 keV for ${\mathrm{H}}_2^{+}$ primaries, and 5 to 120 keV for ${\mathrm{H}}_3^{+}$ primaries. The yield cross sections of the various dissociation fragments of ${\mathrm{H}}_2^{+}$ and ${\mathrm{H}}_3^{+}$ primaries are found to vary as much as 20% with changes in ion source operating conditions. It is proposed that this variation is due to changes in the population of internal energy states of the primary ions. Results obtained for ${\mathrm{H}}_2^{+}$ primary ions are compared with the results of other investigators.