Investigation of the Beam Quality from High Current Ion Sources on HOSTI

With the coming FAIR project at GSI the requirements for beam brilliance for heavy ion beams provided by the high current injector will increase, especially for uranium ions. To perform and to demonstrate the required improvements the high current test injector (HOSTI) has been built up. The main purpose of HOSTI is an optimization of the experimental setup of a high current ion source and the post acceleration gap to increase the beam brilliance [1]. The investigations have been performed in two stages [2]. The first stage of investigations includes the measurements of the transversal ion beam emittance with slit-grid scanner installed directly behind the post acceleration gap. The measurements were performed with a singly charged Arbeam provided by MUCIS with fixed ion velocity of 2.2 keV per nucleon (actual requirements of existing RFQ). During this stage the beam emittance has been investigated as a function of the following parameters: ratio between extraction (Uext.) and post acceleration (UPA) voltages at fixed ion energy; width of the high voltage gap in the post acceleration system; emission current density of the ion source; ion beam current in the beamline. For the second stage of the measurements the superconducting solenoid (built by Cryogenic LTD) was installed directly behind the post acceleration gap. The solenoid represents a two-magnet system with the main coil in the middle and two serially connected compensation coils positioned symmetrically at each end of the main coil.