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Shishlo, A. P.

Paper Title Page
TUPP042 Status of the ORBIT Code: Recent Developments and Plans 1637
 
  • J. A. Holmes, S. M. Cousineau, A. P. Shishlo
    ORNL, Oak Ridge, Tennessee
  
  We report on recent enhancements to the physics modules of the ORBIT Code and on progress toward a new implementation of ORBIT using python. We have developed the capability to track particles through general three dimensional electromagnetic field configurations. This facility has proved essential in modeling beam transport through the complicated magnetic field regions of the SNS injection chicane and injection dump line, where beam losses are high. We have also enhanced the acceleration module to provide more flexibility for synchrotron calculations. Finally, progress continues on the migration of the ORBIT physics models to a python user environment, and we present the status of this work.  
TUPP043 Computational Beam Dynamics Studies of Collective Instabilities Observed in SNS 1640
 
  • J. A. Holmes, S. M. Cousineau, V. V. Danilov, A. P. Shishlo
    ORNL, Oak Ridge, Tennessee
  • L. K. Jain
    UW/Physics, Waterloo, Ontario
  
  During the commissioning and early operation of the Spallation Neutron Source, some physcics shifts were set aside for high intensity stability studies. Under certain, especially contrived conditions, a number of beam instabilities were induced. These included both electron cloud and ring impedance driven phenomena. In this paper we apply both simple analytic models and the ORBIT Code to the description and simulation of these observed instabilities.  
THPC036 Model Based Orbit Correction in a Diagnostics Deficient Region 3056
 
  • A. P. Shishlo, A. V. Aleksandrov
    ORNL, Oak Ridge, Tennessee
  
  A method is presented for an orbit correction in a region where the number of beam position monitors is much less than the number of possible trajectory distortions points (quads). The method was developed for the Coupled Cavities Linac (CCL) part of the Spallation Neutron Source (SNS) linac. The orbit correction is very important in this region to minimize losses and activation, but the usual orbit correction method did not work here. The new method is based on a usage of a realistic online model. The parameters of the model were defined by multidimensional fitting procedure with a substantial array of measured trajectories in CCL. The procedure of parameters finding, model, and results are discussed.  
THPP073 Performance of the SNS Front End and Warm Linac 3530
 
  • A. V. Aleksandrov, C. K. Allen, S. M. Cousineau, V. V. Danilov, J. Galambos, J. A. Holmes, D.-O. Jeon, T. A. Pelaia, M. A. Plum, A. P. Shishlo, M. P. Stockli, Y. Zhang
    ORNL, Oak Ridge, Tennessee
  
  The Spallation Neutron Source accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of an H- injector, capable of producing one-ms-long pulses at 60 Hz repetition rate with 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The 2.5 MeV beam from the Front End is accelerated to 86 MeV in the Drift Tube Linac, then to 185 MeV in a Coupled-Cavity Linac and finally to 1 GeV in the Superconducting Linac. With the completion of beam commissioning, the accelerator complex began operation in June 2006 and beam power is being gradually ramped up toward the design goal. Operational experience with the injector and linac will be presented including chopper performance, longitudinal beam dynamics study, and the results of a beam loss study.  
THPP085 Status of the SNS Ring Power Ramp Up 3560
 
  • M. A. Plum, A. V. Aleksandrov, C. K. Allen, S. M. Cousineau, V. V. Danilov, J. Galambos, J. A. Holmes, D.-O. Jeon, T. A. Pelaia, A. P. Shishlo, Y. Zhang
    ORNL, Oak Ridge, Tennessee
  
  Beam was first circulated in the SNS ring in January 2006. Since that time we have been working to raise the beam power to the design value of 1.4 MW. In general the power ramp up has been proceeding very well, but several issues have been uncovered. Examples include poor transmission of the waste beams in the injection dump beam line, cross-plane coupling in the ring to target beam transport line, and higher-than-expected peak densities in the ring to target transport. In this paper we will discuss these issues and present an overall status of the ring and the transport beam lines.  
THPP044 Experience with the SNS SC Linac 3461
 
  • Y. Zhang, A. V. Aleksandrov, C. K. Allen, I. E. Campisi, S. M. Cousineau, V. V. Danilov, J. Galambos, J. A. Holmes, D.-O. Jeon, S.-H. Kim, T. A. Pelaia, A. P. Shishlo
    ORNL, Oak Ridge, Tennessee
  
  The SNS SC linac (SCL) is designed to deliver 1 GeV, up to 1.56 MW pulsed H- beams for neutron production. Beam commissioning of the SNS accelerator systems completed in June 2006 with the maximum linac output beam energy approximately 952 MeV. In 2007, we successfully tuned the SCL for 1 GeV beams during a test run, and the SNS linac achieved its design energy for the first time. During the linac tune-up, phase scan signature matching, drifting beam measurement as well as linac RF cavity phase scaling was applied. In this paper, we will introduce the experiences with the SCL, and we will also briefly discuss beam parameter measurements.