| Paper |
Title |
Page |
| MOPCH169 |
High Pressure Rinsing Water Jet Characterization
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460 |
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- D. Sertore, E. Cavaliere, M. Fusetti, P. Michelato, C. Pagani, P. Pierini
INFN/LASA, Segrate (MI)
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High pressure rinsing is widely used as the final wet step in the high field superconducting cavities production. The interaction of an high speed ultra pure water jet with the niobium surface depends on various parameters such as water pressure, water throughput, treatment duration, cavity rotation speed, etc. In this paper we illustrate a simple technique for the characterization of water jet parameters based on the momentum transfer between the water jet and a load cell. The jet profile and its dependence on water pressure as well as the force exerted by the jet on the surface are easily measured. Moreover a portable apparatus has been set up and the information gathered in different laboratories will be used for a quantitative comparison of the different HPR systems. These measurements allow to study the correlation of the jet parameters with the effects (surface status, oxide formation, corrosion, etc) of the water interaction with the niobium surface. Furthermore a new analysis, based on the luminescence induced on transparent dielectric samples, is used for confirmation of the water jet structure.
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| MOPCH170 |
Experimental and Theoretical Analysis of the Tesla-like SRF Cavity Flanges
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463 |
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- L. Monaco, P. Michelato, C. Pagani, N. Panzeri
INFN/LASA, Segrate (MI)
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In view of the future large SC accelerator, an improvement of the reliability and a cost reduction of the SRF cavities cold flanges is required. In this paper, a critical analysis of the TESLA-like cold connection flanges at room and at cryogenic temperature is presented. This analysis is based on experimental characterization of the mechanical properties of the joint and of the leak rates during the sealing process. A FEM model, that agrees with the experimental data, is also presented. This model is being used for the optimization of the present SRF flanges and the development of new cold connections.
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| MOPCH171 |
ILC Coaxial Blade Tuner
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466 |
| |
- C. Pagani, A. Bosotti, P. Michelato, N. Panzeri, R. Paparella, P. Pierini
INFN/LASA, Segrate (MI)
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A coaxial (blade) tuner solution has been developed for the compensation of the Lorentz force detuning of the superconducting cavities under the high gradient pulsed operation foreseen for ILC operation. The device is based on prototypes successfully tested at DESY in 2002 both on CHECHIA and on the superstructures inserted in the TTF string. During both tests the blade tuner performed as expected in terms of stiffness, frequency sensitivity and tuning capabilities. An improvement of the tuner characteristics has been designed by the integration of fast tuning capabilities by means of piezo-ceramic element. Two prototipes of the new INFN coaxial piezo blade tuner have just been manufactured and they will be tested at DESY and BESSY after the cavity integration. In this paper the blade tuner design and main characteristics are presented, together with the early interpretation of the cold test results.
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| WEPLS051 |
Dark Current Investigation of TTF and PITZ RF Guns
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2493 |
| |
- L. Monaco, P. Michelato, C. Pagani, P. Pierini, D. Sertore
INFN/LASA, Segrate (MI)
- J.H. Han, S. Schreiber
DESY, Hamburg
- M. Krasilnikov, F. Stephan
DESY Zeuthen, Zeuthen
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The dark current is one of the limiting factor in the operation of RF guns at high gradient. The continuous request of higher brilliance sources and further emittance minimization, leads to apply higher gradients in the RF gun cavity, with the consequence of a significant dark current production. In this context we set up a collaborative effort to identify the dark current sources in the gun, in order to discriminate between the gun and cathode contribution. A critical analysis and organization of dark current measurements, taken during the operation of TTF and PITZ guns, with several cathodes operated at different accelerating fields and solenoids focusing, is presented. Potential areas of improvement are also discussed, together with a possible associated program.
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| WEPLS052 |
High QE Photocathode at FLASH
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2496 |
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- D. Sertore, P. Michelato, L. Monaco, C. Pagani
INFN/LASA, Segrate (MI)
- J.H. Han, S. Schreiber
DESY, Hamburg
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The RF gun-based photoinjector of the VUV-FEL/TTF at DESY continues to use high quantum efficiency (QE) photocathodes produced at LASA, Milano. To study the photocathode behavior during beam operation, an online QE monitoring tool has been installed. In this paper, we present the hardware and software setup for the online QE measurement and the results so far obtained. The measured QEs are usually higher than at TTF phase 1. We compare the QE values taken in the RF gun with data measured just after production with a continuous UV light source.
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