• S.-H. Kim, D.E. Anderson, I.E. Campisi, F. Casagrande, M.T. Crofford, R.I. Cutler, G.W. Dodson, J. Galambos, T.W. Hardek, S. Henderson, R. Hicks, M.P. Howell, D. Jeon, Y.W. Kang, K.-U. Kasemir, S.W. Lee, J. Mammosser, M.P. McCarthy, 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

The Spallation Neutron Source (SNS) is a second generation pulsed-neutron source and designed to provide a 1-GeV, 1.44-MW proton beam to a mercury target for neutron production. Since the initial commissioning of accelerator complex in 2006, the SNS has begun neutron production operation and beam power ramp-up has been in progress toward the design goal. Since the design beam power is almost an order of magnitude higher compared to existing neutron facilities, all subsystems of the SNS were designed and developed for substantial improvements compared to existing accelerators and some subsystems are first of a kind. Many performance and reliability aspects were unknown and unpredictable, for which it takes time to understand the systems as a whole and/or needs additional performance improvements. A power ramp-up plan has been revised based on the operation experiences and understandings of limits and limiting conditions through extensive studies with an emphasis on machine availability. In this paper the operational experiences of SNS Superconducting Linac (SCL), the power ramp-up status and plans will be presented including related subsystem issues.

• M.H. Awida
  University of Tennessee, Knoxville, Tennessee
• M.H. Awida
  ORNL RAD, Oak Ridge, Tennessee
• Y.W. Kang, S.-H. Kim, S.W. Lee, J.L. Wilson
  ORNL, Oak Ridge, Tennessee

RF properties of twisted waveguide structures were investigated to show that slow-wave accelerating fields can be excited and used for acceleration of particle at various velocities lately. To build a practical accelerating cavity structure using the twisted waveguide, more development work was needed: cavity structure tuning, end wall effect of the structures, incorporating beam pipes and input power coupler, and HOM damping, etc. In this paper, the practical aspects of the designs to make more complete accelerating structures are discussed with the results of computer simulations.