• L.A. Dahl, W. Barth, P. Gerhard, F. Herfurth, M. Kaiser, O.K. Kester, H.J. Kluge, S. Koszudowski, C. Kozhuharov, G. Maero, W. Quint, A. Sokolov, T. Stöhlker, W. Vinzenz, G. Vorobjev, D.F.A. Winters
  GSI, Darmstadt
• B. Hofmann, J. Pfister, U. Ratzinger, A.C. Sauer, A. Schempp
  IAP, Frankfurt am Main

For injection into the ion trap facility HITRAP, the GSI accelerator complex has the unique possibility to provide beams of highly stripped ions and even bare nuclei up to Uranium at an energy of 4 MeV/u. The HITRAP facility consists of linear 108 MHz-structures of IH^- and RFQ-type to decelerate the beams further down to 6 keV/u for capturing in a large penning trap for cooling purpose. The installation is completed except of the RFQ-tank. During commissioning periods in 2007 ⁶⁴Ni²⁸⁺ and ²⁰Ne¹⁰⁺ beam was used to investigate the beam optics from the experimental storage ring extraction to the HITRAP double-drift-buncher system. In 2008 the IH-structure decelerator and the downstream matching section was examined with ¹⁹⁷Au⁷⁹⁺ beam. Comprehensive beam diagnostics were installed: Faraday cups, tubular and short capacitive pick ups, SEM grids, YAG scintillation screens, a single shot pepperpot emittance meter, and a diamond detector for bunch shape measurements. Results of the extensive measurements are presented.

• W. Vinzenz, W. Barth, H.-L. Dambowy, L. Groening, M. Hoerr, G. Schreiber
  GSI, Darmstadt

During the LINAC conference in Knoxville 2006 the operating frequency of the FAIR proton linac was fixed at 325.224 MHz. Even though the six CH-Structures need slightly different rf levels, the proton linac will be equipped with identical rf power sources. That applies although for the RFQ structure. To supply the FAIR accelerators with a good beam quality by the UNILAC as the high current heavy ion injector for FAIR, as well as an high duty factor accelerator for nuclear physics experiments, different upgrades and modifications have to be made at the rf components. In addition there has to be an upgrade for a planned 50% duty cycle mode, higher beam load within the post-stripper section as well as the provision of an excellent rf operation for the next 30 years. Discussions on possible collaborations with CERN in terms of LLRF and the combining of the procurement for tube amplifiers for bunching cavities are on the way. This paper describes the actual status of the proton linac rf system and the future requirements for the existing UNILAC rf systems.

• E. Feldmeier
  HIT, Heidelberg
• G. Hutter, B. Schlitt, W. Vinzenz
  GSI, Darmstadt

For the heavy ion therapy center HIT in Heidelberg a 1.6 MW power amplifier for 217 MHz was built to supply the 7 MeV/u IH cavity. The inherent parasitic oscillations of the RF tube increases rapidly the anode current until the system switches off. For the elimination of those parasitic oscillations ferrite material is used. The electro magnetic fields are simulated to find an optimal positioning of the ferrite material in the anode cavity such that only the parasitic oscillations are attenuated without affecting the fundamental mode.