Electron-impact ionization cross-section measurements for ${\mathrm{U}}^{10+}$, ${\mathrm{U}}^{13+}$, and ${\mathrm{U}}^{16+}$

Absolute measurements are presented for electron-impact single ionization of ${\mathrm{U}}^{10+}$, ${\mathrm{U}}^{13+}$, and ${\mathrm{U}}^{16+}$, and for double ionization of ${\mathrm{U}}^{10+}$ and ${\mathrm{U}}^{13+}$ from below the thresholds to 1500 eV. Metastable components are observed in all three incident-ion beams. The single-ionization cross sections are enhanced due to indirect ionization processes by factors of 4–20 near their peaks, and the double-ionization cross sections are apparently also dominated by indirect ionization. Good agreement is found with distorted-wave calculations for total ionization of ${\mathrm{U}}^{16+}$, the only case where detailed calculations are available for comparison. Individual or closely spaced resonances are clearly resolved in the single-ionization channels for ${\mathrm{U}}^{13+}$ and ${\mathrm{U}}^{16+}$.