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Other Keywords |
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| TUPLS047 |
An Analysis of Lumped Circuit Equation for Side Coupled Linac (SCL)
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coupling, linac, insertion, booster |
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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linac, proton, cyclotron, acceleration |
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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coupling, linac, booster, simulation |
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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| TUPLS057 |
Linac4, a New Injector for the CERN PS Booster
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linac, rfq, CERN, emittance |
1624 |
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- R. Garoby, G. Bellodi, F. Gerigk, K. Hanke, A.M. Lombardi, M. Pasini, C. Rossi, E.Zh. Sargsyan, M. Vretenar
CERN, Geneva
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The first bottle-neck towards higher beam brightness in the LHC injector chain is due to space charge induced tune spread at injection in the CERN PS Booster (PSB). A new injector called Linac4 is proposed to remove this limitation. Using RF cavities at 352 and 704 MHz, it will replace the present 50 MeV proton Linac2, and deliver a 160 MeV, 40 mA H beam. The higher injection energy will reduce space charge effects by a factor of 2, and charge exchange will drastically reduce the beam losses at injection. Operation will be simplified and the beam brightness required for the LHC ultimate luminosity should be obtained at PS ejection. Moreover, for the needs of non-LHC physics experiments like ISOLDE, the number of protons per pulse from the PSB will increase by a significant factor. This new linac constitutes an essential component of any of the envisaged LHC upgrade scenarios, which can also become the low energy part of a future 3.5 GeV, multi-megawatt superconducting linac (SPL). The present design has benefited from the support of the French CEA and IN2P3, of the European Union and of the ISTC (Moscow). The proposed machine and its layout on the CERN site are described.
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| THPCH156 |
SNS Transverse and Longitudinal Laser Profile Monitors Design, Implementation and Results
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laser, electron, SNS, linac |
3161 |
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- S. Assadi
ORNL, Oak Ridge, Tennessee
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SNS is using a Nd:YAG laser to measure transverse profiles at nine-stations in the 186-1000 MeV Super-Conducting LINAC (SCL) and a Ti:Sapphire mode-locked laser to measure longitudinal profiles in the 2.5 MeV Medium Energy Beam Transport (MEBT). The laser beam is scanned across the H- beam to photo-neutralize narrow slices. The liberated electrons are directly collected to measure the transverse or longitudinal beam profiles. We have successfully measured the transverse and longitudinal profiles at all stations. The SCL laser system uses an optical transport line that is installed alongside the 300 meter super-conducting LINAC to deliver laser light at nine locations. Movement of the laser light in the optical transport system can lead to problems with the profile measurement. We are using telescopes to minimize the oscillations and active feedback system on mirrors to correct the drifts and movements. In this paper we present our implementation and beam profiles measured during SCL commissioning. We also discuss future improvements, drift/vibration cancellation system, as well as plan to automate subsystems for both the transverse and the longitudinal profiles.
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