Proton and Ion Accelerators and Applications

2E - Superconducting Linacs

Paper Title Page
MO103 SNS Superconducting Linac Operational Experience and Upgrade Path 11
  • S.-H. Kim
    ORNL, Oak Ridge, Tennessee

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy
The SNS Superconducting Linac (SCL) has been providing the main acceleration in two different accelerating sections with 33 medium beta and 48 high beta superconducting radio-frequency (SRF) 6-cell cavities. The use of superconducting elliptical cavities for particles whose velocity are less than the speed of light, make this accelerator a very important milestone for learning operating conditions of this cavity type. Since the SNS SCL is the first large-scale high energy pulsed-superconducting proton linac that provides high beam power utilizing H- beams, many aspects of its performance were unknown and unpredictable. A large amount of data has been collected on the pulsed behavior of cavities and cryomodules at various repetition rates and at various temperatures. This experience will be of great value in determining future optimizations of SNS as well in guiding in the design and operation of future pulsed superconducting linacs. This paper describes the details of the rf properties, performances, path-forward for the SNS power ramp-up goal, and upgrade path of the SNS superconducting linac.


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MOP052 Re-phasing of the ISAC Superconducting Linac with Computed Values 193
  • M. Marchetto, R.E. Laxdal, F. Yan
    TRIUMF, Vancouver

The ISAC superconducting linac is a fully operational machine that routinely provides beam to experiments. The linac consists of twenty superconducting independently phased cavities housed in five cryomodules. The initial tune is done manually aided by MATLAB routines to phase the linac and set the correct optics. From the initial tune we calculate the gradient at which each cavity operates based on the energy gain, the transit time factor and the geometry of the cavity itself. Then in the event of a gradient change of one or more cavities we can calculate the rf phase shift of each downstream cavity using the initial gradients, the known geometry of the entire linac and assuming linearity of the rf controls. This possibility has been investigated and we have demonstrated that the calculated phase shift can be implemented automatically thus avoiding a complete retune of the machine. In this paper we will present the calculations and the results of the online tests.

MOP053 The SPIRAL 2 Superconducting Linac 196
  • R. Ferdinand
    GANIL, Caen
  • P.-E. Bernaudin, P. Bosland
    CEA, Gif-sur-Yvette
  • Y. Gómez-Martínez
    LPSC, Grenoble
  • T. Junquera, G. Olry, H. Saugnac
    IPN, Orsay

The SPIRAL2 superconducting linac is composed of 2 cryomodule families, basically one of low beta, called Cryomodule A, and one of high beta, called Cryomodule B. The low beta family is composed of 12 single cavity cryomodule. The high energy section is composed of 7 cryomodules hosting 2 cavities each. According to beam dynamics calculations all the cavities will operate at 88 MHz: one family at beta=0.07, and one at beta=0.12. The design goal for the accelerating field Eacc of the SPIRAL2 QWRs is : 6.5 MV/m. The configuration, cavities and cryomodule tests and status and the foreseen linac tuning will be described.

MOP054 Experience with Stripping Carbon Foils in ALPI Super-Conducting Accelerator 199
  • P.A. Posocco
    Consorzio RFX, Associazione Euratom-ENEA sulla Fusione, Padova
  • D. Carlucci, A. Pisent, M. Poggi, P.A. Posocco
    INFN/LNL, Legnaro, Padova

The superconducting linac ALPI, injected either by a XTU tandem or by the superconducting RFQ of PIAVE, is composed by 3 cryostats of bulk Nb cavities (β=0.056) and 13 cryostats of Nb sputtered on Cu cavities (β=0.11 and β=0.13), for a total of 64 cavities and an equivalent voltage of 35MV. The linac is build up in two branches connected by an achromatic and isochronous U-bend. In January 2007 a stripping station equipped with carbon foils of different thickness was placed after 6 cryostats, before the U-bend, to test the feasibility of acceleration and transport of a charge enhanced beam. The study was performed with 4 different beams (Ca, Ar, Zr and Xe) and a complete data analysis has been carried out.

MOP055 Plans for a Superconducting H- Linac (SPL) at CERN 202
  • R. Garoby, O. Brunner, S. Calatroni, E. Ciapala, F. Gerigk, A.M. Lombardi, R. Losito, V. Parma, C. Rossi, J. Tuckmantel, M. Vretenar, W. Weingarten
    CERN, Geneva

As part of the upgrade of the LHC injector complex at CERN, the construction of a 4 GeV Superconducting Proton Linac (the SPL, in fact an H- accelerator) is planned to begin in 2012. Depending upon physics requests, it should be upgradeable to 5 GeV and multi-MW beam power at a later stage. The construction of Linac4, its low energy front end, has started at the beginning of 2008. A full project proposal with a cost estimate for the low power version of the SPL aimed at improving LHC performance has to be ready for mid-2011. As a first step towards that goal, essential machine parameters like rf frequency, cooling temperature and beam current have recently been revisited and plans have been drawn for designing and testing critical components. The SPL parameters are reviewed in the context of the CERN plans for upgrading the LHC injectors, and the foreseen developments during the next years are described.

MOP056 The Status of the MSU Re-Accelerator (ReA3) 205
  • X. Wu, S. Chouhan, C. Compton, M. Doleans, W. Hartung, D. Lawton, G. Machicoane, F. Marti, P.S. Miller, J. Ottarson, M. Portillo, R.C. York, A. Zeller, Q. Zhao
    NSCL, East Lansing, Michigan

The Re-accelerator being developed at the Michigan State University is a major component of a novel system proposed at the NSCL to first stop the high energy RIBs by the in-flight particle fragmentation method in a helium filled gas system, then increase their charge state with an Electron Beam Ion Trap (EBIT) charge breeder, and finally re-accelerate them to about 3 MeV/u, in order to provide opportunities for an experimental program ranging from low-energy Coulomb excitation to transfer reaction studies of astrophysical reactions. The accelerator system consists of a Low Energy Beam Transport (LEBT) with an external multi-harmonic buncher, a radio frequency quadrupole (RFQ) followed by a superconducting linac and a High Energy Beam Transport (HEBT). The superconducting linac will use quarter-wave resonators with bopt of 0.047 and 0.085 for acceleration and superconducting solenoid magnets for transverse focusing. The paper will discuss the recent progress of R&D and beam dynamics studies for the MSU Re-accelerator.

WE202 Operational Experience with High Power Beams at the SNS Superconducting Linac 710
  • J. Galambos
    ORNL, Oak Ridge, Tennessee

The latest operational experiences of the SNS 1 GeV superconducting H- linac will be presented as the beam power is increased and losses and beam halo become more important. The talk will include a comparison of the advantages and disadvantages of superconducting cavities. For example, issues arising from the use of different sets of SC cavities at different times will be described, along with the operational consequences on emittance and halo development.


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TH103 Developing Facilities for SNS Cryomodule Performance Improvements 735
  • J. Mammosser
    ORNL, Oak Ridge, Tennessee

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy
Superconducting rf cavity facilities are currently being developed at SNS aimed at addressing the limitations and availability of installed cavities and the direct support of the future power upgrade plans. Efforts are directed towards development of in situ repairs and processing techniques to increase available linac gradients. Procedures have been developed and implemented and the results will be presented for the repair of four cryomodules in the last year. Cryomodule testing facilities are being developed to further understand the collective limitations of installed cavities and spare cryomodule production is underway to develop and fabricate two high beta and one medium beta cryomodules. The direction and status of SRF facilities will be presented.


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TH202 Heavy Ion Linac Booster at IUAC, New Delhi 749
  • A. Roy
    IUAC, New Delhi

The first module of the booster superconducting linear accelerator, consisting of a total of three modules, each having 8 quarter wave coaxial line bulk Nb resonators, has been commissioned at IUAC. During initial operation of the first linac module, the energy gain was found to be much lower due to various problems which are now identified and solved. After acceleration through the linac module and subsequent re-bunching using a superconducting Rebuncher, a 158 MeV silicon beam having pulse width of 400 ps was delivered to conduct nuclear physics experiments. The other two linac cryostats and the required 16 resonators to be installed in those two cryostats are in the final stage of fabrication. Work has progressed on a high current injector that would act as an alternate source of heavy ions for the superconducting linac. The first element of the high current injector is a high Tc superconducting magnet ECR source (PKDELIS) which would be followed by a room temperature radio frequency quadrupole accelerator and drift tube linac cavities. Prototypes of the RFQ working at 48.5 MHz, and that of the DTL working at 97 MHz, have been fabricated and are undergoing tests.


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