An ion beam cooler and buncher has beendeveloped for the manipulation of radioactive ion beams. The gas-lled linear radiofrequency ion trap system is installed at the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN. Its purpose is to accumulate the 60-keV continuous ISOLDE ion beam with high e ciency and to convert it into low-energy low-emittance ion pulses. The e ciency was found to exceed 10 % in agreement with simulations. A more than 10-fold reduction of the ISOLDE beam emittance can beachieved. The system has beenused successfully for rst on-line experiments. Its principle, setup and performance will be discussed.

We investigate the heating of the quasi-free electrons in large rare gas clusters (N exceeding 10 5 atoms) by short laser pulses at moderate intensities (I ≃ 10 15 Wcm −2 ). We identify elastic large-angle backscattering of electrons at ionic cores in the presence of a laser field as an efficient heating mechanism resembling the Fermi shuttle. Its efficiency as well as the effect of collective electron motion, electron-impact ionization and cluster charging, are studied employing a meanfield classical transport simulation. Results for the absolute x-ray yields are in surprisingly good quantitative agreement with recent experimental results.

We have performed a systematic study of the Bremsstrahlung emission from the electrons in the plasma of a commercial 14.5 GHz Electron-Cyclotron Resonance Ion Source. The electronic spectral temperature and the product of ionic and electronic densities of the plasma are measured by analyzing the Bremsstrahlung spectra recorded for several rare gases (Ar, Kr, Xe) as a function of the injected power. Within our uncertainty, we find an average temperature of ≈ 48 keV above 100W, with a weak dependency on the injected power and gas composition. Charge state distributions of extracted ion beams have been determined as well, providing a way to disentangle the ionic density from the electronic density. Moreover X-ray emission from highly charged argon ions in the plasma has been observed with a high-resolution mosaic crystal spectrometer, demonstrating the feasibility for high-precision measurements of transition energies of highly charged ions, in particular of the magnetic dipole (M1) transition of He-like of argon ions.