Electronic temperatures, densities and plasma X-ray emission of a 14.5 GHz Electron-Cyclotron Resonance Ion Source

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

Projectile charge and velocity effect on UO2O_2 sputtering in the nuclear stopping regime

Expérience GANI

Contribution of ion emission to sputtering of uranium dioxide by highly charged ions

Measurements of the cluster size (n) distribution of secondary (UO$_{x})^{+}_{n}$ ions from sputtering of uranium dioxide (UO$_{2})$ by Ne8+, Ar8+ and Xe$^{q+}$ ions (q=10, 23) at fixed kinetic energy (81 keV) have been performed with a time-of-flight mass spectrometer. The cluster ion yields Y follow a power law $Y(n)\sim n^{\delta}$ with $-2.1<\delta <-1.5$. This is in contrast to a statistical recombination of the constituents upon ejection, but in agreement with the predictions of collective ejection models. Such a power law was also observed in the electronic stopping regime with MeV/u ions. The exponent $\delta$ is found to decrease with increasing projectile mass (and thus total sputter yield) at fixed kinetic energy. The ratio of emitted ionic clusters to monomers varies from 3 to 4.5 depending on the projectile. The contribution of positive ions to the total sputtering yield amounts to about 0.03%