HIGH CHARGE STATES ION BEAMS FROM SOLID MATERIALS WITH THE SUPERCONDUCTING ECR ION SOURCE SERSE S. Gammino, G. Ciavola, L. Celona, M. Castro, F. Chines, S. Marletta, E. Messina INFN-LNS, Catania, Italy G. Melin, A. Girard, D. Hitz, CEA-DRFMC-SI2A, Grenoble, France Abstract The superconducting electron cyclotron resonance (ECR) ion source SERSE, developed by INFN/LNS of Catania and CEA/DRFMC of Grenoble, is operational since 1997 and it has produced the highest currents for highly charged ion beams of gaseous elements. In 1999- 2000 the production of highly charged ion beams from solid materials have been the most relevant task, because the source is now coupled to the K-800 Superconducting Cyclotron and there was a large request of heavy elements from users. The paper will report the most relevant results in terms of high charge state production and stability. Preliminary results of tests in afterglow mode will be also discussed. 1 INTRODUCTION The superconducting Electron Cyclotron Resonance (ECR) ion source SERSE [1,2,3] was designed on the basis of the concept of High B mode [1,4] (i.e. the radial magnetic field must exceed the value of 2·B ECR , where B ECR is the resonance magnetic field, corresponding to 0.52 T for the frequency of 14.5 GHz and 0.64 T for the frequency of 18 GHz). The source construction has been completed in 1997 at the Grenoble testbench and the source is operating at LNS since June 1998. The main features of the source are described in tab. 1 and other details may be found in [1,2]. Table 1: The main features of SERSE Frequency 18 GHz + 14.5 GHz Available power 2 kW + 2 kW Type of launching WR62, off-axis Axial maxima distance about 490 mm B max (injection side) 2.7 T B min 0.3 to 0.6 T B max (extraction side) 1.6 T Resonance zone length < 100 mm Hexapole length 700 mm B rad (at chamber wall) 1.55 T maximum LHe consumption 4 l/h φ plasma electrode 8 mm φ puller 12 mm Extraction voltage 20 kV Vacuum 2*10 -8 mbar 2 THE HIGH TEMPERATURE OVEN The high temperature oven is available since 1997 [5] but it was not extensively used until 1999, when the axial injection line for the Superconducting Cyclotron became operational and the injection by means of ECRIS sources replaced the radial injection by means of a 15 MV Tandem. The beams to be developed for nuclear physics experiments were mainly heavy ion beams, available from solid materials, by means of the high temperature oven. The oven optimization faced many mechanical constraints: the cryostat did not permit a radial positioning of the oven and the insertion along the axis or parallel to it was also limited by the microwave and gas injection system, leaving the room for a 35 mm tube, to be used for oven and biased disk. Thus the first version of the oven (fig. 1), which has been used up to now, did not use a bias voltage, limiting in such a way the achievable currents. Another limitation of this oven was the unavailability of a vacuum valve to substitute the crucible without breaking the vacuum. Moreover, the presence of long current leads (900 mm) to feed the oven, which orifice is located 50 mm inside the plasma chamber, was the major concern in terms of reliability, reproducibility and stability of the source. Figure 1: The oven with its current leads, before the insertion into the source. 1595 Proceedings of EPAC 2000, Vienna, Austria