Institut des
NanoSciences de Paris

Clusters and Surfaces under Strong Excitations

Dynamics with slow highly charged ions

Production of intense ion beams : We recently installed an ECR (Electron Cyclotron Resonance) ion source called SIMPA (Source d’Ions Multichargés de PAris) that we share with the Laboratoire Kastler Brossel (group of Paul Indelicato). In such a source, the plasma is heated by a microwave radiation. The electrons, which moves in a magnetic field, are accelerated when the frequency of the microwave radiation matches the cyclotron frequency (i.e. the gyration frequency of the electrons in the magnetic field). Our first works were to optimise the performances of SIMPA by measuring, under given experimental conditions, the electron and ion temperatures in the plasma as well as the respective densities. All those measurements have been also related to the characteristics of extracted ion beams.

Ref : « Electronic temperatures, densities, and plasma x-ray emission of a 14.5 GHz electron-cyclotron resonance ion source » Rev. Sci. Instrum. vol 81 p 033303

Interaction with free clusters : One of our projects is to study collisions of slow Highly Charged Ions (HCI) with rare gas clusters. The use of multicharged ions represents an interesting tool for investigating the static properties of clusters, and for determining basic interaction mechanisms in electron dynamics involved in production and decay of projectile multiply excited states, as well. Moreover, interesting feature of such a target is that clusters have a wide and variable surface compare to bulk when varying the cluster size. When an HCI approaches the cluster, a multiply-excited ion is formed. Exited state populations, charge state and energy loss depend upon the cluster region the HCI interacts. Studying x-ray emission from the projectile in coincidence with its charge state, should allow to separate ions interacting with surface from those crossing the bulk of the cluster. An experiment is planned at the ARIBE facility (GANIL, Caen-France).

Interaction with surfaces : Ion-cluster interaction is a first step towards the study of the dynamics slow highly charged ions on surfaces. At the INSP, the scientific environment and the available techniques should provide strong assets to develop this research in an original way and the program foreseen will cover several new aspects.