Measurement of Charge Exchange between H2 and Low-Energy Ions with Charge States 35

Abstract

Charge-exchange cross sections for collisions between ${\mathrm{H}}_{2}$ and ions with unusually low center-of-mass energies (\ensuremath{\approx}6 eV) and high-charge states (${\mathrm{Xe}}^{q+}:35, 43\ensuremath{\le}q\ensuremath{\le}46$, ${\mathrm{Th}}^{q+}:73\ensuremath{\le}q\ensuremath{\le}80$) have been measured using a Penning ion trap. A nondestructive measurement technique permitted both primary and product ion analysis. The data, averaged over the charge states indicated above, are consistent with a total cross section that scales linearly with ion charge $q$. The true double-capture cross section is found to be about 25% of the total cross section at high $q$. The results are compared to predictions of the absorbing-sphere model.