Pulsed Low Level Baseband RF Control of CH-Cavities for p-Linac at FAIR

At the Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany a high intensity antiproton beam will be produced. To provide the necessary 70 mA proton beam a dedicated proton linac (p-Linac) is under construction. The main acceleration will be provided by 9 novel CH-type cavities, of which 6 will be coupled in pairs to share the same klystron. To test the rf properties of these novel cavities, a test stand is under construction. An rf control system for the pulsed operation of these cavities has been developed at TU Darmstadt. It is based upon the digital cw rf control that is successfully in operation as part of the S-DALINAC at IKP Darmstadt. The latest developments will be presented. THE P-LINAC TEST-STAND AT FAIR The Facility for Antiproton and Ion Research (FAIR) will be an international research infrastructure connected to the GSI Helmholtzzentrum fur Schwerionenforschung (GSI) at Darmstadt, Germany. One of the main features of FAIR will be research using antiproton beams. In order to produce an antiproton beam that meets the needs of the experiments and the limitations of the beam transport, a pulsed proton beam of an energy of up to 70 MeV and a peak current of up to 70 mA is needed. This proton beam will be provided by a dedicated linac, the p-Linac, for injection into the SIS18 synchrotron. The main acceleration of protons in the p-Linac will be provided by normal conducting, crossed-bar, h-mode (CH) cavities with a frequency of 325 MHz. These cavities will be driven by pulsed 2.5 MW klystrons [1]. These novel cavities and their peripheral devices have to be tested. Therefore an RF test stand is under construction at GSI. For this test stand a pulsed RF control system is needed. It has to achieve an amplitude stability of 10 -3 and a phase stability of 0.1°. An RF control system that meets this requirements has been developed at TU Darmstadt. It is based on the digital RF control system of the Superconducting Darmstadt Linear Electron Accelerator (S-DALINAC) [2].