PROGRAM TO IMPROVE THE ION BEAM FORMATION AND TRANSMISSION AT JYFL H. Koivisto, T. Ropponen, J. Ropponen, T. Koponen, M. Savonen, V. Toivanen, P. Heikkinen, JYFL, Jyväskylä, Finland G. Machicoane, J. Stetson, P. Zavodszky, X. Wu, M. Doleans, S. Chouhan, NSCL/MSU, East Lansing, Michigan, USA P. Spädtke, (GSI), Darmstadt, Germany H. Beijers and S. Brandenburg, KVI, Groningen, Netherlands Abstract The increased requirements towards the use of higher ion beam intensities motivated us to initiate the project to improve the overall transmission efficiency of the K130 cyclotron facility at JYFL. A similar project has earlier been started at the NSCL/MSU (National Superconducting Cyclotron Laboratory/Michigan State University) where a remarkable improvement in the ion beam transmission has been obtained [1]. Since similar improvement plans were considered at the KVI (Kernfysisch Versneller Instituut) the natural choice was to carry out the common improvement work in collaboration between the afore-mentioned laboratories. In this article we present the beam transport efficiency of the JYFL cyclotron facility in different operation conditions, the experiments to discover the “bottle-necks” and plans to solve the problems. The objective of this program is to double the accelerated beam intensity of medium charge states. The Ar 8+ ion beam is used as a benchmark, which at present the maximum intensity is about 8 μA after the cyclotron. BEAM TRANSMISSION Experimental set-up The JYFL 14 GHz ECRIS is the main tool for the ion beam production required by the JYFL nuclear physics programme. The performance of the ion source is typically adequate but large beam emittance growth in the beam extraction from the ECRIS and in the beam injection line limits the usable beam intensity after the cyclotron. Figure 1 shows the layout of the beam line from the ion source to the emittance scanner located after the 90˚ analysing magnet. After the ion source extraction the beam is focused by two solenoids (SOLJ1, SOLJ2), collimated by a 20 mm (5/10/20) collimator and analyzed by a R500 dipole (DJ1). The gap of the dipole is 85 mm. After the dipole the ion beam is focused again through a 20 mm collimator and its intensity is measured by a Faraday cup. Ion beam can be focused by a solenoid (SOLJ3) into the Allison type 2D emittance scanner. After the dipole the beam shape can be analyzed with the KBr beam viewing plates. The beam profile in the vertical direction can be seen also with the aid of the emittance measurements. Figure 1: The layout of the JYFL 14 GHz ECRIS beam line. Present beam transmission efficiency According to the transmission experiments carried out at JYFL the beam transmission efficiency decreases with the beam intensity extracted from the JYFL 14 GHz ECRIS. Here the transmission efficiency is I PFC /I FCJ2 , where I PFC and I FCJ2 (see Fig. 1) are the beam intensities measured after the K130 cyclotron and after the ECRIS, Cyclotrons and Their Applications 2007, Eighteenth International Conference 337