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Galambos, J.

Paper Title Page
WPAT085 4.2 K Operation of the SNS Cryomodules 4173
 
  • I.E. Campisi, S. Assadi, F. Casagrande, M. Champion, C. Chu, S.M. Cousineau, M.T. Crofford, C. Deibele, J. Galambos, P.A. Gurd, D.R. Hatfield, M.P. Howell, D.-O. Jeon, Y.W. Kang, K.-U. Kasemir, Z. Kursun, H. Ma, M.F. Piller, D. Stout, W.H. Strong, A.V. Vassioutchenko, Y. Zhang
    ORNL, Oak Ridge, Tennessee
 
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos and Oak Ridge.

The Spallation Neutron Source being built at the Oak Ridge National Laboratory employs eighty one 805 MHz superconducting cavities operated at 2.1 K for the H- beam to gain energy in the main linac from 187 MeV to about 1 GeV. The superconducting cavities and cryomodules with two different values of beta .61 and .81 have been designed and constructed at Jefferson Lab for operation at 2.1 K with unloaded Q’s in excess of 5x109. To gain experience in testing cryomodules in the SNS tunnel before the final commissioning of the 2.1 K Central Helium Liquefier, integration tests were conducted on a medium beta (.61) cryomodule at 4.2 K. This is the first time that a superconducting cavity system specifically designed for 2.1 K operation has been extensively tested at 4.2 K without superfluid helium. Even at 4.2 K it was possible to test all of the functional properties of the cryomodule and of the cavities. In particular, at a nominal BCS Qo˜7x108, simultaneous pulse operation of all three cavities in the cryomodule was achieved at accelerating gradients in excess of 12 MV/m. These conditions were maintained for several hours at a repetition rate of 30 pps. Details of the tests will be presented and discussed.

 
ROPA001 XAL Application Programming Structure 79
 
  • J. Galambos, C. Chu, S.M. Cousineau, V.V. Danilov, J.G. Patton, T.A. Pelaia, A.P. Shishlo
    ORNL, Oak Ridge, Tennessee
  • C.K. Allen
    LANL, Los Alamos, New Mexico
 
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

XAL is an application programming framework used at the Spallation Neutron Source (SNS) project in Oak Ridge. It is written in Java, and provides users with a hierarchal view of the accelerator. Features include database configuration of the accelerator structure, an online envelope model that is configurable from design or live machine values, an application framework for quick-start GUI development, a scripting interface for algorithm development, and a common toolkit for shared resources. To date, about 25 applications have been written, many of which are used extensively in the SNS beam commissioning activities. The XAL framework and example applications will be discussed.

 
FPAE049 Development and Implementation of ?T Procedure for the SNS Linac 3064
 
  • A. Feschenko, S. Bragin, Y. Kiselev, L.V. Kravchuk, O. Volodkevich
    RAS/INR, Moscow
  • A.V. Aleksandrov, J. Galambos, S. Henderson, A.P. Shishlo
    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 ?t procedure is a time of flight technique for setting the phases and amplitudes of accelerating fields in a multi-cavity linac. It was initially proposed and developed for the LAMPF linac in the early seventies and since then has been used in several accelerators. The SNS linac includes four CCL modules (Side Coupled Structure) operating at 805 MHz for the energy range from 86.8 MeV up to 185.6 MeV. The ?t procedure has been implemented for the SNS CCL linac and was used for its initial beam commissioning. Brief theory of the procedure, the results of the design parameter calculations and the experimental results of phase and amplitude setpoints are presented and discussed.

 
FPAE057 Beam Dynamics Studies and Beam Quality in the SNS Normal-Conducting Linac 3381
 
  • S. Henderson, A.V. Aleksandrov, D.A. Bartkoski, C. Chu, S.M. Cousineau, V.V. Danilov, G.W. Dodson, J. Galambos, D.-O. Jeon, M.A. Plum, M.P. Stockli
    ORNL, Oak Ridge, Tennessee
 
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos and Oak Ridge.

The Spallation Neutron Source accelerator systems will provide a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron production. The accelerator complex consists of an H- injector capable of producing 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The linear accelerator consists of a Drift Tube Linac, a Coupled-Cavity Linac and a Superconducting Linac which provide 1.5 mA average current to the accumulator ring. The staged beam commissioning of the accelerator complex is proceeding as component installation progresses. Recently, the normal-conducting linear accelerator was beam commissioned. A number of beam dynamics and beam quality measurements will be reported, including the measurement of transverse emittances in the H- injector, and the evolution of halo and emittance along the linac.

 
FPAE058 Spallation Neutron Source Superconducting Linac Commissioning Algorithms 3423
 
  • S. Henderson, I.E. Campisi, J. Galambos, D.-O. Jeon, Y. Zhang
    ORNL, Oak Ridge, Tennessee
 
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos and Oak Ridge.

We describe the techniques which will be employed for establishing RF and quadrupole setpoints in the SNS superconducting linac. The longitudinal tuneup will be accomplished using phase-scan methods, as well as a technique that makes use of the beam induced field in the unpowered cavity.* The scheme for managing the RF and quadrupole setpoints to achieve a given energy profile will be described.

*L. Young, Proc. PAC 2001, p. 572.

 
FPAT016 PASTA – An RF Phase and Amplitude Scan and Tuning Application 1491
 
  • J. Galambos, A.V. Aleksandrov, C. Deibele, S. Henderson
    ORNL, Oak Ridge, Tennessee
 
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

To assist the beam commissioning in the Spallation Neutron Source (SNS) linac, a general purpose RF tuning application has been written to help set RF phase and amplitude. It follows the signature matching procedure described in Ref.* The method involves varying an upstream Rf cavity amplitude and phase settings and comparing the measured downstream beam phase responses to model predictions. The model input for cavity phase and amplitude calibration and for the beam energy are varied to best match observations. This scheme has advantages over other RF tuning techniques of not requiring intercepting devices (e.g. Faraday Cups), and not being restricted to a small linear response regime near the design values. The application developed here is general and can be applied to different RF structure types in the SNS linac. Example applications in the SNS Drift Tube Linac (DTL) and Coupled Cavity Linac (CCL) structures will be shown.

*T.L. Owens, M.B. Popovic, E.S. McCrory, C.W. Schmidt, L. J. Allen, "Phase Scan Signature Matching for Linac Tuning," Particle Accelerators, 1994 Vol 98, p. 169.