| Paper |
Title |
Page |
| MOPCH140 |
Compensation of Lorentz Force Detuning of a TTF 9-cell Cavity with a New Integrated Piezo Tuner
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378 |
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- G. Devanz, P. Bosland, M. Desmons, E. Jacques, M. Luong, B. Visentin
CEA, Gif-sur-Yvette
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The high gradient operation of superconducting elliptical multicells in pulsed mode is required for linear colliders or free-electron lasers based on the superconducting technology. Such an operation is limited by dynamic Lorentz force detuning if no compensation for this effect is attempted. The RF power headroom required for accelerating field amplitude and phase stabilisation by low-level RF control techniques solely would be too costly. A new active tuner with integrated piezo actuators has been developped in the framework of the european CARE/SRF program solve this issue. The design is based on the lever-arm concept of the Saclay tuner already installed on running TTF cavities. We have carried out integrated tests of the 9-cell cavity equipped with the piezo tuner and power coupler in the CryHoLab horizontal test cryostat. Characterisation of the electromechanical system consisting of the cavity and piezo-tuner assembly and full power pulsed tests will be presented.
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| TUPCH007 |
High Resolution BPM for the Linear Colliders
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1004 |
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- C. Simon, S. Chel, M. Luong, O. Napoly, J. Novo, D. Roudier
CEA, Gif-sur-Yvette
- N. Rouvière
IPN, Orsay
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The beam-based alignment and feedback systems which are essential for the operation of the future colliders use some high resolution Beam Position Monitors (BPM). In the framework of CARE/SRF, the task of CEA/DSM/DAPNIA (Saclay) is the design, the fabrication and the beam test of a BPM in collaboration with DESY. This system is composed of a RF re-entrant cavity with a beam pipe radius of 78mm and an analog electronics having several signal processing steps to reject the monopole mode. Thanks to its high position resolution (better than 1μm) and its high time-resolution (around 10ns), it is a candidate for the X-FEL at DESY and the ILC. Indeed the chosen coupling allows the bunch to bunch measurement and the separation between the monopole and dipole modes. Moreover, this BPM is designed to be used in a clean environment, at the cryogenic and room temperatures.
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| TUPCH186 |
Low Level RF System Development for SOLEIL
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1447 |
| |
- P. Marchand, M.D. Diop, F. Ribeiro, R.S. Sreedharan
SOLEIL, Gif-sur-Yvette
- M. Luong, O. Piquet
CEA, Gif-sur-Yvette
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The Low Level RF system that is used in the SOLEIL storage ring consists in fully analog "slow" amplitude, phase and frequency loops, complemented with a direct RF feedback. A fast digital FPGA-based I/Q feedback, currently under development, will be implemented later on. The performance of both systems has been evaluated using a Matlab-Simulink-based simulation tool. The computed and first experimental results are reported.
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| MOPLS059 |
The Probe Beam Linac in CTF3
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679 |
| |
- A. Mosnier, M. Authier, D. Bogard, A. Curtoni, O. Delferriere, G. Dispau, R. Duperrier, W. Farabolini, P. Girardot, M. Jablonka, J.L. Jannin, M. Luong, F. Peauger
CEA, Gif-sur-Yvette
- N. Rouvière
IPN, Orsay
- R. Roux
LAL, Orsay
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The test facility CTF3, presently under construction at CERN within an international collaboration, is aimed at demonstrating the key feasibility issues of the multi-TeV linear collider CLIC. The objective of the probe beam linac is to "mimic" the main beam of CLIC in order to measure precisely the performances of the 30 GHz CLIC accelerating structures. In order to meet the required parameters of this 200 MeV probe beam, in terms of emittance, energy spread and bunch-length, the most advanced techniques have been considered: laser triggered photo-injector, velocity bunching, beam-loading compensation, RF pulse compression … The final layout is described, and the selection criteria and the beam dynamics results are reviewed.
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| THPCH159 |
Analysis of Microphonic Disturbances and Simulation for Feedback Compensation
|
3167 |
| |
- M. Luong, P. Bosland, G. Devanz, E. Jacques
CEA, Gif-sur-Yvette
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For FEL projects based on a superconducting linac operating in CW mode, the RF power optimization finally comes up against the microphonics disturbances, which result in an unpredictable detuning of the cavities. A new piezoelectric tuner was developed and mounted on a TTF 9-cell cavity with an appropriate instrumentation. This system enables a full characterization of the disturbances and the tuner behavior. First measurements were made in a horizontal cryomodule at 4.2 K. They set a basis for simulations to assess the possibility of a feedback compensation, which is usually credited as impracticable. The outcome of such a compensation is also shown in terms of acceleration voltage amplitude and phase residual errors.
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