GSI, Darmstadt
For the FAIR project, the intensity of heavy-ion beams in SIS-18 has to be increased by an order of magnitude. In order to achieve the design intensities, the efficiency of the multiturn injection from the UNILAC has to be optimized for high beam currents. This is especially important for the operation with intermediate charge state heavy-ions, where beam loss during injection will lead to pressure bumps and to a reduced lifetime of the beam. The multiturn injection into SIS-18 is studied by virtue of particle tracking simulations using an extended version of the computer code PATRIC. The impact of space charge and other intensity effects on the efficiency of the injection process is analyzed.
GSI, Darmstadt
TEMF, TU Darmstadt, Darmstadt
A study of the transverse dynamics of coasting ion beams with moderate space charge is presented. An analytic model based on the dispersion relation with a linear space-charge force is used to describe the impact of space charge on transverse beam transfer functions (BTFs) and the stability limits of a beam. The dielectric function obtained in this way is employed to describe the transverse Schottky spectrum with linear space charge as well. The difference between space charge and impedance effects is highlighted. An experiment performed in the heavy ion synchrotron SIS-18 at GSI to detect space-charge effects at different beam intensities is explicated. The measured transverse Schottky spectra, BTFs and stability diagrams are compared with the analytic model. The space-charge parameters evaluated from the Schottky and BTF measurements are compared with estimations based on measured beam parameters. Furthermore, particle tracking simulations demonstrating the impact of collective effects on the Schottky and BTF diagnostics are presented. The simulation results are used to verify the space-charge model.
