Status of the 3 1⁄2 Cell Rossendorf Superconducting Rf Gun

The status of the Rossendorf superconducting RF gun is discussed. This gun allows continuous wave operation with an energy of 9.5 MeV and an average current of 1mA. The 31⁄2 cell niobium cavity contains a normal conducting photocathode. A special choke flange filter at the cathode side prevent the RF leakage of the cavity. The design of the cavity, the tuner, the RF coupler the LHevessel together with the cryostat is finished and now in manufacturing. In the paper three features are discussed, which follows from the special demands of the 31⁄2 cell superconducting RF gun. The first feature is the tuning system. For the cavity two different tuners are necessary, one for the half cell (gun cell) and one for the accelerating cells. The second feature is the tuning of the cathode. The beam properties depend very sensitive on the cathode position. Therefore a special cathode tuner has been developed, which allows to move and to adjust the cathode position inside the cavity. The third no conventional feature is the excitation of a second RF mode inside the cavity. This is a magnetic mode (TE mode) which replaces the static magnetic field in normal conducting RF guns and decreases the transverse emittance of the beam by more than a factor of two. Contribution to the conference FEL 2004, Trieste, Italy Work supported by the European Community-Research Infrastructure Activity under the FP6 « Structuring the European Research Area » programme (CARE, contract number RII3-CT2003-506395). STATUS OF THE 3 1⁄2 CELL ROSSENDORF SUPERCONDUCTING RF GUN D. Janssen, H. Büttig, P. Evtushenko, U. Lehnert, P. Michel, Ch. Schneider, J. Stephan, J. Teichert, Forschungszentrum Rossendorf, Dresden, Germany V. Volkov, S. Kruchkov, O. Myskin, BINP SB RAS, Novosibirsk, Russia Abstract The status of the Rossendorf superconducting RF gun is discussed. This gun allows continuous wave operation with an energy of 9.5 MeV and an average current of 1mA. The 31⁄2 cell niobium cavity contains a normal conducting photocathode. A special choke flange filter at the cathode side prevent the RF leakage of the cavity. The design of the cavity, the tuner, the RF coupler the LHevessel together with the cryostat is finished and now in manufacturing. In the paper three features are discussed, which follows from the special demands of the 31⁄2 cell superconducting RF gun. The first feature is the tuning system. For the cavity two different tuners are necessary, one for the half cell (gun cell) and one for the accelerating cells. The second feature is the tuning of the cathode. The beam properties depend very sensitive on the cathode position. Therefore a special cathode tuner has been developed, which allows to move and to adjust the cathode position inside the cavity. The third no conventional feature is the excitation of a second RF mode inside the cavity. This is a magnetic mode (TE mode) which replaces the static magnetic field in normal conducting RF guns and decreases the transverse emittance of the beam by more than a factor of two.The status of the Rossendorf superconducting RF gun is discussed. This gun allows continuous wave operation with an energy of 9.5 MeV and an average current of 1mA. The 31⁄2 cell niobium cavity contains a normal conducting photocathode. A special choke flange filter at the cathode side prevent the RF leakage of the cavity. The design of the cavity, the tuner, the RF coupler the LHevessel together with the cryostat is finished and now in manufacturing. In the paper three features are discussed, which follows from the special demands of the 31⁄2 cell superconducting RF gun. The first feature is the tuning system. For the cavity two different tuners are necessary, one for the half cell (gun cell) and one for the accelerating cells. The second feature is the tuning of the cathode. The beam properties depend very sensitive on the cathode position. Therefore a special cathode tuner has been developed, which allows to move and to adjust the cathode position inside the cavity. The third no conventional feature is the excitation of a second RF mode inside the cavity. This is a magnetic mode (TE mode) which replaces the static magnetic field in normal conducting RF guns and decreases the transverse emittance of the beam by more than a factor of two.