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| MOPCH167 |
PBG Superconducting Resonant Structures
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454 |
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- M.R. Masullo
INFN-Napoli, Napoli
- A. Andreone, E. Di Gennaro, F. Francomacaro, G. Lamura
Naples University Federico II, Napoli
- V. Palmieri, D. Tonini
INFN/LNL, Legnaro, Padova
- M. Panniello, V.G. Vaccaro
Naples University Federico II and INFN, Napoli
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We have realized normal conducting and superconducting “open resonators” based on the Photonic Band Gap (PBG) concept. We present the study, the optimisation and the measurements (from room temperature to 1.5 K) of Copper and Niobium PBG accelerating cavities operating at two different frequencies, 6 GHz and 16 GHz. All the structures are realised by extruding a single bulk piece of material, using a new machining method that minimizes the surface losses caused by the contact between different conducting parts. Measurements on the compact (54 mm external diameter) 16 GHz Nb structure are very good, showing in the superconducting state a quality factor Q =1.2x105 at the lowest temperature (1.5 K), limited by radiation losses only. The shunt impedance measured for the 16 GHz prototype is 70 MOhm/m, underlining the applicability of such resonant structures as accelerating cavities.
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| TUPLS047 |
An Analysis of Lumped Circuit Equation for Side Coupled Linac (SCL)
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1600 |
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- V.G. Vaccaro, A. D'Elia
Naples University Federico II and INFN, Napoli
- M.R. Masullo
INFN-Napoli, Napoli
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The behaviour of a SCL module is generally described by resorting to an equation system borrowed from lumped circuit theories. This description holds for a narrow frequency band (mono-modal cavity behaviour). A milestone in this field is represented by the classical analysis made by Knapp & alii where the equations allow for the resonant frequencies of the cavities and the first and second order coupling constants. Eigenvalues and eigenvectors (resonant frequencies of the system and relevant current amplitudes) are also given. We show that the system is not correct in the second and last but one equations for the case of half cell termination and non zero second order coupling constants. Due to the relevance of this formulation and of the case treated, we pay a particular attention to find the missing terms in the above mentioned equation. We suggest a correction term, having in addition a deep meaning from electromagnetic point of view. By means of this term we may justify the analytical solution given by the authors. Some numerical examples are also given showing that a discrepancy appears comparing the new equations with the results of the non-correct formulation.
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| TUPLS048 |
Optimization Design of a Side Coupled Linac (SCL) for Protontherapy: a New Feeding Solution
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1603 |
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- V.G. Vaccaro, A. D'Elia
Naples University Federico II and INFN, Napoli
- T. Clauser, A.C. Rainò
Bari University, Science Faculty, Bari
- C. De Martinis, D. Giove, M. Mauri
INFN/LASA, Segrate (MI)
- S. Lanzone
CERN, Geneva
- M.R. Masullo
INFN-Napoli, Napoli
- R.J. Rush
e2v technologies, Chelmsford, Essex
- V. Variale
INFN-Bari, Bari
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It is proposed to use an SCL, starting at 30MeV, up to 230MeV. The linac consists of 25 modules (two tanks each). Twelve, 3GHz power generators, feed two modules in parallel, with the last power generator feeding the last module. The SCL is designed, assuming a mean accelerating field in the cavities of 16,5MV/m. The longitudinal and transverse beam dynamics has been studied, assuming that the input parameters (emittance, energy spread and mean current) are those of commercial 30MeV cyclotrons. The characteristics of the ejected beam were analysed: the transmittance value is largely sufficient to deliver a correct dose for therapy; the beam line activation is kept largely below allowed levels; the output energy spread is sufficiently small. The first prototype module is under construction and a second one is under design. Contacts with e2v have been established for defining an agreement, which proposes to use magnetrons as feeders for the acceleration tests. Attention was therefore paid to phase locking constraints between feeders. Theoretical studies suggest that transmittance stays constant if de-phasing is kept into values that seem attainable with magnetrons.
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| TUPLS049 |
A Rationale to Design Side Coupled Linac (SCL): a Faster and More Reliable Tool
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1606 |
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- V.G. Vaccaro, A. D'Elia
Naples University Federico II and INFN, Napoli
- M.R. Masullo
INFN-Napoli, Napoli
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A module of an SCL is formed by a cascade of two or more tanks, connected by a Bridge Couplers (BC) with an RF feeder, which realizes a well defined accelerating field configuration in all the coupled cavities. Even resorting to geometrical scaling for the design of the adjacent tanks in the module it is not possible to reproduce the same e-m parameters. In addition to this the BC's for each tanks have a different geometrical design because of phasing constraints. The standard procedure may leads a very slow convergence of the design to the optimum and it is not in general clear if the optimum is reached. In this paper a rationale for designing a module of an SCL will be described and it will be presented its application to PALME first module (30-3???MeV). From a lumped circuit model one may get useful relations between e-m global response of the system and single cell parameters. Therefore it provides a certain number of tools which are used for the designing steps in connection with the standard electromagnetic CAD's, the results of which were used as "measurements".
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| WEOBPA01 |
First Results of the CRFQ Proof of Principle
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1873 |
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- D. Davino
Universita' degli Studi del Sannio, Benevento
- L. Campajola
Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli
- V. Lo Destro, A.G. Ruggiero
BNL, Upton, Long Island, New York
- M.R. Masullo
INFN-Napoli, Napoli
- V.G. Vaccaro
Naples University Federico II and INFN, Napoli
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The Circular Radiofrequency Quadrupole is a new concept of a storage and accelerator ring for intense beams of light and heavy ions, protons and electrons. It is basically a Linear Radiofrequency Quadrupole completely bent on a circle. The advantages, which are expected to be the same performance features of a linear RFQ, would be smaller overall dimension with respect to accelerators with comparable beam intensity and emittance*. A collaboration between BNL and Italian research institute and universities was set up at the end of 2002 with the aim of the proof of the bending principle**. The prototype design is based on a 4-rods scheme and have a linear sector followed by a 45-degree curved sector. The 1mA proton beam, produced by a reconditioned RF source, go through a beam gap diameter of 10mm with circular 10mm diameters rods. Each sector is 700mm long and is placed in a 150mm diameter pipe***. The RF power at 202.56MHz is fed by a CERN "Frank James" 50kW amplifier. In this paper the first power and beam tests of the linear sector are presented.
*A.G. Ruggiero, C-A/AP/65 note, Brookhaven National Laboratory, October 2001. **A.G. Ruggiero et al., Proceedings of the EPAC 2004 conference.***D. Davino et al., Proceedings of the EPAC 2004 conference.
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