A pilot study has lead to evidence for the successful trapping of externally created supra-thermal multiply-charged heavy ions in an electrostatic trap. Recoil ions produced by heavy-ion impact on atoms in a gas target have been extracted from the collision region and formed into a charge-analysed secondary ion beam. Some of these ions have been captured into an electrostatic ion trap designed to allow for the ion beam divergence and the finite observation angle of the detector. Such a confinement of ions in a trap is a prerequisite for the measurement of lifetimes in the range of 10 μs to 10 ms of long-lived excited states of multiply-charged ions.

The beam-foil spectrum obtained using a beam of Ti3+ ions of energy 10 MeV has been studied over the wavelength range from 14 nm to 80 nm. New assignments are suggested for 18 levels belonging to the levels of the 3p3, 3s 3p 3d and 3s2 4p configurations. The lifetimes of these levels, as determined from conventional multi-exponential curve fitting of their intensity decay curves, are typically about 30% longer than is forecast by theory. The same decay curves have also been used to represent the effect of cascade repopulation on the decay curves obtained for the resonance doublet levels of the 3s 3p2 and 3s2 3d configurations. A discussion is given of the possible techniques for cascade correction in beam-foil lifetime measurements, and of the inclusion of a window function to represent the vignetting effect close to the foil. Lifetimes obtained using these techniques for the 3s2 3d levels (38±6 ps for J=3/2, 36±5 ps for J=5/2), and the 3s3p22S level (99±6 ps),2P levels (60±15 ps for J=1/2, 50±15 ps for J=3/2) and2D levels (820±30 ps for j=3/2, 870±40 ps for J=5/2) are in good agreement with theoretical predictions.

The charge-state distribution of neon recoil ions produced by ion-atom collisions has been investigated with ${\mathrm{Ni}}^{\mathrm{p}+}$, ${\mathrm{Cu}}^{\mathrm{p}+}$, and ${\mathrm{N}}^{2+}$ projectiles. The dependence of recoil-ion production on the ionization state of the primary ions has been investigated for two projectile energies in an intermediate velocity range not previously studied. Absolute net-ionization and charge-specific cross sections have been determined and are compared with other experiments and with theoretical predictions.

The yield of recoil ions from collisions of highly charged heavy ions or N 2+ ions with neon has been studied in a projectile energy regime intermediate between recent low- and high-energy experiments.

Using the method of beam-foil spectroscopy we have measured the decay times of several n = 3 terms in Mg-like Ni XVII. By applying an effective method for correction of cascades (ANDC) we obtained reliable lifetimes for the terms 3s3p1P, 3s3p3P, 3p2 1D and 3p2 3P. The experimental data are in good agreement with recent theoretically predicted values.

Few-electron ions of argon have been produced by heavy ion impact in a gas target. The recoil ions have been extracted into a region with high vacuum, and the K radiation of long-lived states has been observed by means of a position sensitive proportional counter oriented along the flight path of the ions.

The3P1, 2−5S 2 o intercombination lines in Ni14+ have been identified in the EUV spectrum emitted by foil-excited Ni ion beams. The wavelengths are close to the theoretically predicted values. The relative intensities of the lines confirm the predicted branching ratios.