ABSTRACT:The transport simulation of a high intensity ions beam with a radio-frequency cooler within the SPIRAL 2/GANIL High Intensity Radiofrequency Cooler, SHIRAC, installed at the SPIRAL 2/DESIR facility, is presented. Two simulation methods of cooling process in presence of space charge effect will be studied. The beam properties degradation by the coulomb repulsion and the buffer gas diffusion will be discussed. Finally, a comparison in term of transmission between simulated and experimental results for 133 Cs + ions beam of intensity going up to 1µA, will be outlined.

International audienceWithin the framework of the DESIR/SPIRAL-2 project, a radio-frequency quadrupole cooler named SHIRaC has been studied. SHIRaC is a key device of SPIRAL-2, designed to enhance the beam quality required by DESIR. The preliminary study and development of this device has been carried out at Laboratoire de Physique Corpusculaire de CAEN (LPC Caen), France. The goal of this paper is to present the experimental studies conducted on a SHIRaC prototype. The main peculiarity of this cooler is its efficient handling and cooling of ion beams with currents going up as high as 1  μA which has never before been achieved in any of the previous coolers. Much effort has been made lately into these studies for development of appropriate optics, vacuum and rf systems which allow cooling of beams of large emittance (∼80π  mm mrad) and high current. The dependencies of SHIRaC’s transmission and the cooled beam parameters in terms of geometrical transverse emittance and the longitudinal energy spread have also been discussed. Investigation of beam purity at optimum cooling condition has also been done. Results from the experiments indicate that an emittance reduction of less than 2.5π  mm mrad and a longitudinal energy spread reduction of less than 4 eV are obtained with more than 70% of ion transmission. The emittance is at expected values whereas the energy spread is not