| Paper |
Title |
Page |
| MOPCH103 |
SPIRAL2 RFQ Prototype – First Results
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282 |
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- R. Ferdinand, R. Beunard, V. Desmezières, M. Di Giacomo, P. Robillard
GANIL, Caen
- A.C. Caruso
INFN/LNS, Catania
- S. Cazaux, M. Desmons, A. France, D. Leboeuf, O. Piquet, J.-C. Toussaint
CEA, Gif-sur-Yvette
- M. Fruneau, Y. Gómez-Martínez
LPSC, Grenoble
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The SPIRAL2 RFQ has been designed to accelerate a 5 mA deuteron beam (Q/A=1/2) or a 1 mA particle beam with q/A=1/3 up to 0.75 MeV/A at 88MHz. It is a CW machine which has to show stable operation, provide the required availability and reduce losses to a minimum in order to minimize the activation constraints. Extensive modelisation was done to ensure a good vane position under RF. The prototype of this 4-vane RFQ has been built and tested in INFN-LNS Catania and then in IN2P3-LPSC Grenoble. It allowed us to measure the vacuum quality, the RF field by X-ray measurements, the cavity displacement and the real vane displacement during the RF injection. Different techniques were used, including an innovative and effective CCD measurement with a 0.6 μm precision. This paper outlines the different results.
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| MOPCH105 |
A New RF Tuning Method for the End Regions of the IPHI 4-vane RFQ
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285 |
| |
- O. Delferriere, M. Desmons, A. France
CEA, Gif-sur-Yvette
- R. Ferdinand
GANIL, Caen
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The 3-MeV High Intensity Proton Injector (IPHI) RFQ is constituted by the assembly of three 2-m-long segments. The tuning of the end regions of such an accelerator with respect to the quadrupole mode is generally made by machining the thickness of the end plates. The dipole modes are moved away from the accelerator mode frequency by adding dipole rods and adjusting their length. In the case of the last IPHI RFQ segment, the tuning range given by possible plate thickness was not sufficient to adjust the frequency at 352 Mhz without modifying the notch depth, leading to serious engineering problems for the cooling, new thermo-mechanical simulations and drawings. To avoid these difficulties, a new way has been investigated by replacing the end plate thickness adjustment by a "quadrupole rod" length adjustment. These rods are situated between the beam axis and the dipole rods, and the tuning range is largely increased. The paper will describe this method applied to the IPHI RFQ and some experimental results obtained on the cold model.
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| MOPCH106 |
An Innovative Method to Observe RFQ Vanes Motion with Full-scale RF Power and Water Cooling
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288 |
| |
- A. France, O. Piquet
CEA, Gif-sur-Yvette
- R. Ferdinand
GANIL, Caen
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The design of high current RFQs is heavily strained by thermo-mechanical considerations, which eventually have an impact on machining costs, cooling systems, etc. A 1-meter long copper prototype of the SPIRAL2 RFQ has been specifically built to corroborate design options. An innovative method has been developed, allowing real-time observation of mechanical deformations of RFQ vanes, with full-scale RF power and water cooling. Digital images are acquired by a CCD camera, and processed by a dedicated software. Processing includes contrast stretching, low-pass filtering, and block-correlation followed by interpolation. Sub-pixel relative motions of RFQ electrode ends are clearly detected and measured, with RMS errors of the order of 0.6 microns.
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| MOPCH107 |
Tuning Procedure of the 6 Meter IPHI RFQ
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291 |
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- O. Piquet, M. Desmons, A. France
CEA, Gif-sur-Yvette
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In the framework of the IPHI project (High Intensity Proton Injector), the RFQ cavity is divided into 6 sections of 1 meter each, and assembled in 3 segments separated by coupling plates. We will present the tuning procedure of the aluminium RFQ cold model to set the accelerating mode frequency, a flat voltage profile and to minimize the dipole components of the accelerating voltage. This tuning procedure can be divided in three steps. First, dipole mode frequencies are adjusted with rods for the 3 separated segments. Second, RFQ end cells and coupling cells are tuned by mechanical machining of tuning plates. Third, using a fully automated bead-pull for the measurement of the field distribution inside every RFQ quadrants, the RFQ is tuned with 96 plungers in a small number of iterations. Tuning this 6-meter long cold model is a comprehensive training in view of the future tuning of the copper RFQ with the variable voltage profile.
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