Upgrade of the H--injection system at the DESY proton linac III

In the near future the injection system of the proton linac at DESY will be upgraded. Two different types of H^--sources are operated at DESY. The new rf-driven volume source is free of cesium. On a long-term basis this source is planned to replace the present operating magnetron source. For reasons of reliability of the proton linac and for further developments of ion sources a parallel operation of two sources should be possible at the Alvarez linac. Each source has a separate RFQ to accelerate the ions to an energy of 750 keV. A new transport line with one dipole, 8 quadrupoles and one intermediate buncher was designed to match the beam between both RFQs and the Alvarez linac. The codes COPPOC and TRANSPORT were used to determine the length of the transport line and the parameters of the dipole and the buncher. Because of the high current of 20 mA and above the estimation of the space charge forces is of special interest. The macro-particle-code PARMTRA takes into account the particle-to-particle electric forces among all particles. The properties of the beam line have been studied in connection with the effects on the final beam quality after acceleration with the 50 MeV Alvarez linac