| Paper |
Title |
Page |
| MOPC072 |
Photocathode Studies at FLASH
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232 |
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- S. Lederer, S. Schreiber
DESY, Hamburg
- J. H. Han
Diamond, Oxfordshire
- P. M. Michelato, L. Monaco, C. Pagani, D. Sertore
INFN/LASA, Segrate (MI)
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Since several years, the DESY photoinjectors at FLASH and PITZ use cesium telluride photocathodes. One concern of operating an electron source with these cathodes is the degradation of the quantum efficiency (QE), starting from about 10 % to below 0.5 % during operation. To further understand this behavior the QE is monitored routinely. In this paper recent results from photocathode studies at FLASH are presented.
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| MOPC075 |
Cs2Te Photocathode Robustness Studies
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241 |
| |
- D. Sertore, P. M. Michelato, L. Monaco, C. Pagani
INFN/LASA, Segrate (MI)
- S. Lederer, S. Schreiber
DESY, Hamburg
- F. Stephan
DESY Zeuthen, Zeuthen
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Cs2Te photocathodes are used as laser driven electron sources at FLASH and PITZ. Besides many aspects of their performances, their robustness to gas exposition and the effect of pollutants on photocathode properties, and indirectly on the photoemitted electrons, are a field still rather unexplored. In this article we present the results of controlled exposition of Cs2Te photocathodes to gases typical present in the UHV environment of an RF Gun with respect to spectral response (QE vs. wavelength), and QE uniformity. Moreover, a comparison between polluted cathodes and fresh ones during operation in an RF Gun is presented.
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| MOPP120 |
Full Characterization of the Piezo Blade Tuner for Superconducting RF Cavities
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838 |
| |
- A. Bosotti, C. Pagani, N. Panzeri, R. Paparella
INFN/LASA, Segrate (MI)
- C. Albrecht, K. Jensch, R. Lange, L. Lilje
DESY, Hamburg
- J. Knobloch, O. Kugeler, A. Neumann
BESSY GmbH, Berlin
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Cavity tuners are mechanical devices designed to precisely match the resonant frequency of the superconducting (SC) cavity to the RF frequency synchronous with the beam. The blade tuner is mounted coaxially to the cavity and changes the resonator frequency by varying its length. A high tuning range is desired together with small mechanical hysteresis, to allow easy and reproducible resonator setup operations. High stiffness is also demanded to the tuner system both to ensure mechanical stability and to mitigate the frequency instabilities induced by perturbations. In high gradient SC resonators, the main sources of resonant frequency instability are the Lorentz Force Detuning (LFD) under pulsed mode operation, and the microphonic noise, in continuous wave (CW) with high loaded quality factors. Piezoceramic elements add dynamic tuning capabilities to the system, allowing fast compensation of these instabilities with the help of feed-forward and feedback loops. The piezo blade tuner has been extensively tested both at room temperature and at cold once assembled on a TESLA type cavity in its final configuration. This paper presents the summary of the complete characterization tests.
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| MOPP146 |
The Coaxial Tuner for ILCTA_NML at Fermilab
|
895 |
| |
- A. Bosotti, C. Pagani, N. Panzeri, R. Paparella
INFN/LASA, Segrate (MI)
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The piezo Blade Tuner prototype has been successfully tested inside the horizontal cryostat, CHECHIA, at DESY and extensive tests at BESSY are planned. As suggested by the cold test results, a few minor modifications have been implemented and a set of 8 improved devices is under construction for the installation in the second module of ILCTA at Fermilab. This reviewed design, together with a simplified helium tank in prototyping, should hopefully fulfill also the XFEL requests in term of performances and cost. In particular the use of thicker blades and their slightly different distribution along the circumference produces the increase of the tuner strength and stiffness that is needed in order to fulfill the pressure vessel regulations for qualification. As in the past, two equivalent devices, respectively in titanium and stainless steel, have been designed to maintain open the possibility of the use of a SS helium vessel once the required technology were developed. The results of the extensive mechanical tests performed to validate the estimated performances and life time are also presented.
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| MOPP154 |
Study of the High Pressure Rinsing Water Jet Interactions
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910 |
| |
- D. Sertore, M. Fusetti, P. M. Michelato, C. Pagani
INFN/LASA, Segrate (MI)
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High Pressure Rinsing (HPR) is an important step in the cleaning of Superconducting Cavities (SC). The understanding of the interaction of the high pressure water jet on the cavity wall is of primary importance for the optimization of this process for upcoming SC based projects like XFEL and ILC. In this paper, we extend our results obtained so far in different labs and present our studies on water jet interaction on oblique surfaces and the possible induced damages.
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