INFN/LASA, Segrate (MI)
DESY, Hamburg
BESSY GmbH, Berlin
Cavity tuners are needed to precisely tune the narrow-band resonant frequency of superconducting cavities. The Blade Tuner presented is installed coaxially to the cavity and changes the resonator frequency by varying its length. Piezoceramic actuators add dynamic tuning capabilities, allowing fast compensation of main dynamic instabilities as Lorentz Forces, under pulsed operations, and microphonic noise. A prototype piezo Blade Tuner has been assembled on a TESLA cavity and extensively cold tested inside the horizontal cryostats CHECHIA (DESY) and HoBiCaT (BESSY). Then, as suggested by results, a few minor modifications have been implemented thus achieving the current Blade Tuner design. The introduction of thicker blades re-distributed along the circumference allows to increase its stiffness and fulfill European and American pressure vessel codes, while ensuring requested performances and cost. The paper will present the successful characterization tests performed on the prototype, the extensive mechanical analyses made to validate the final model and the results from qualification tests of first revised Blade Tuner produced, to be installed in the second module of ILCTA at FNAL.
DESY Zeuthen, Zeuthen
INRNE, Sofia
DESY, Hamburg
YerPhI, Yerevan
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
INFN/LASA, Segrate (MI)
BESSY GmbH, Berlin
Uni HH, Hamburg
MEPhI, Moscow
Funding: This work was partly supported by the European Community, contracts RII3-CT-2004-506008 and 011935, and by the 'Impuls- und Vernetzungsfonds' of the Helmholtz Association, contract number VH-FZ-005.
The Photo Injector Test facility at DESY, Zeuthen site, (PITZ) was built to develop and optimize high brightness electron sources for Free Electron Lasers (FELs) like FLASH and the European XFEL. In the last shutdown a new RF gun cavity with improved water cooling was installed and conditioned. It is the first rf gun where the surface cleaning was done with dry ice technique instead of high pressure water rinsing and it showed a 10 times lower dark current emission than its precursor gun, even at cathode gradients as high as 60M V/m. In addition, a new photo cathode laser system was installed and will be available for operation in spring 2008. It will allow flat-top temporal laser shapes with 2ps rise/fall time. According to beam dynamics simulations this will further improve the beam quality reported at earlier conferences* and will lead to unprecedented low transverse projected emittance beams at a charge level of 1nC. This contribution will summarize the experimental results from the summer 2008 running period covering transverse projected emittance optimization, thermal emittance from the photocathode, longitudinal phase space and first transverse slice emittance measurements.
* L. Staykov et al., "Measurements of the Projected Normalized Transverse Emittance at PITZ", Proceedings of the FEL 2007, Novosibirsk, Russia, August 2007.
