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Jeon, D.-O.

Paper Title Page
MOP045 Performance of SNS Front End and Warm Linac 145
 
  • A. V. Aleksandrov, S. Assadi, W. Blokland, P. Chu, S. M. Cousineau, V. V. Danilov, C. Deibele, J. Galambos, S. Henderson, D.-O. Jeon, M. A. Plum, A. P. Shishlo, M. P. Stockli
    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 60Hz repetition rate with 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The 2.5MeV 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. Injector and warm linac performance results will be presented including transverse emittance evolution along the linac, longitudinal bunch profile measurements at the beginning and end of the linac, and the results of a beam loss study.  
TUP032 Comparison of SNS Superconducting Cavity Calibration Methods 315
 
  • Y. Zhang, I. E. Campisi, P. Chu, J. Galambos, S. Henderson, D.-O. Jeon, K.-U. Kasemir, A. P. Shishlo
    ORNL, Oak Ridge, Tennessee
  
  Three different methods have been used to calibrate the SNS superconducting cavity RF field amplitude. Two are beam based and the other strictly RF based. One beam based method uses time-of-flight signature matching (phase scan method), and the other uses the beam-cavity interaction itself (drifting beam method). Both of these methods can be used to precisely calibrate the pickup probe of a SC cavity and determine the synchronous phase. The initial comparisons of the beam based techniques at SNS did not achieve the desired precision of 1% due to the influence of calibration errors, noise and coherent interfaces in the system. To date the beam-based SC cavity pickup probe calibrations agree within approximately 4%, comparable to the conventional RF calibrations.  
TUP070 Comparison of Phase Scan vs Acceptance Scan for the SNS DTL 415
 
  • D.-O. Jeon
    ORNL, Oak Ridge, Tennessee
  
  There are two widely used techniques for setting the rf set-point of the Drift Tube Linac (DTL). The Phase Scan and the Acceptance Scan techniques were applied to the SNS DTL and were benchmarked against each other. Commissioning data indicate that both techniques produce quite consistent results and the model used is quite accurate. Both of the models are based on multiparticle tracking with space charge effects.  
TUP071 Beam-Loading Effects on Phase Scan for the Superconducting Cavities 418
 
  • D.-O. Jeon, S. Henderson, S.-H. Kim, Y. Zhang
    ORNL, Oak Ridge, Tennessee
  
  When the beam is passing through superconducting cavities, it excites beam induced field in cavities. A systematic study was performed to study the beam loading effects by the nonrelativistic beam for β = 0.81 superconducting cavities of the SNS linac. The analysis indicates that the induced field level is quite close to the estimation and its effect on the phase scan is consistent with the model.  
TUP076 First TRACK Simulations of the SNS Linac 432
 
  • B. Mustapha, V. N. Aseev, P. N. Ostroumov, J. Xu
    ANL, Argonne, Illinois
  • S. Henderson, D.-O. Jeon
    ORNL, Oak Ridge, Tennessee
  
  In an effort to benchmark the code TRACK* against the recent commissionnig data from the SNS linac, we started updating the code TRACK to support SNS-type elements like DTL's and CCL's. 2D electric field tables were computed using SUPERFISH and 3D magnetic fields from PMQ's were calculated using EMS-Studio. A special DTL routine was implemented and successfully tested. The first results of TRACK simulations using a realistic beam will be presented. A comparison with the code PARMILA will also be presented and discussed.

* "TRACK: The New Beam Dynamics code", V. N. Aseev et al, in Proceedings
of PAC-05 Conference, Knoxville, Tennessee, May 16-20, 2005.

 
THP081 Study on Fault Scenarios of Coaxial Type HOM Couplers in SRF Cavities 770
 
  • S.-H. Kim, I. E. Campisi, F. Casagrande, M. S. Champion, M. T. Crofford, D.-O. Jeon, Y. W. Kang, M. P. McCarthy, D. Stout
    ORNL, Oak Ridge, Tennessee
  
  Coaxial type couplers are adopted in many superconducting radio-frequency (SRF) cavities to suppress higher order modes for beam dynamics and cryogenic loads issues. HERA (Hadron-Electron Ring Accelerator) and TTF (Tesla Test Facility) are equipped with this type coupler and showed successful performances. It is, however, under suspicion that a limitation or a fault could be initiated from this type of coupler at certain combinations between cavity operating conditions and engineering designs of the coupler. Some possible scenarios are summarized and also some observations in the SNS (Spallation Neutron Source) SRF cavities are also reported.