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ECRIS 2008

Ion beam production from rare isotopes with GSI ECR Ion Sources

ECR ion sources (ECRIS) of CAPRICE-type, working at 14.5 GHz, are in use at the High Charge State Injector (HLI) of the accelerator facility at GSI for beam production and at a test bench for development work. The ECRIS is mostly used to produce ion beams from rare isotopes because of its high efficiency and low material consumption. Depending on their material properties beams of rare isotopes are produced from gases, gaseous compounds, solid materials or solid compounds. Gases can be used directly, while solids have to be transformed into the gaseous state for the ECR plasma which is achieved by using resistively heated ovens. As enriched materials are produced by isotopic separation processes their composition including contamination by impurities can be of importance for the handling in the evaporation process and can be detrimental for the beam user if the ion beam contains additional ion species. Characteristics and suitable treatment of materials and production processes are described. Experimental investigations with different sample materials and operational experiences are reported.  more...

Author: K. Tinschert et al.

Low Energy Beam Transport for Ion Beams created by an ECRIS

It has been shown previously that the emittance of an ion beam, extracted from an Electron Cyclotron Resonance Ion Source (ECRIS) is determined by magnetic field, applied electric potentials, geometry, and particle density distribution together with the initial properties of these particles.

The model used for computer simulation seems to fit the experimental results: ions are extracted from the ion source if they are created (started) at places where magnetic field lines are going through the extraction aperture. Furthermore, the absolute value of magnetic flux density relative to the flux density at the extraction aperture defines, whether this ion can be extracted or not.

Due to coupling between the different subspaces of phase space because of the magnetic field, several assumptions used for beam transport issues are not valid any more: for example, two-dimensional emittance does not stay constant in every case; the six dimensional phase space does.

With increasing extracted ion currents, space charge compensation of the extracted beam becomes an important issue. The beam itself will create secondary particles which can serve for space charge compensation. This compensation will build up in a relatively short time, depending on the pressure, as long no leakage is present within the beam line.  more...

Author: P. Spädtke et al.