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Kang, Y. W.

Paper Title Page
MOPP091 Upgrade of Input Power Coupling System for the SNS RFQ 763
 
  • Y. W. Kang, A. V. Aleksandrov, P. E. Gibson, T. W. Hardek, C. Luck, R. C. Peglow, A. V. Vassioutchenko
    ORNL, Oak Ridge, Tennessee
  
  A RF input power coupler system has been developed for upgrade of input coupling to the RFQ in the SNS linac front-end. The design employs two coaxial loop couplers for 402.5 MHz operation. Two couplers are used in parallel to power the accelerating structure with up to 800 kW total peak power at 8% duty cycle. Each coupler loop has a coaxial ceramic window that is connected to each output of a magic-T waveguide hybrid splitter through a coaxial to waveguide transition. The coaxial loop couplers have been designed, manufactured, and high power processed. This paper presents the following: RF and mechanical designs of the couplers and system, procedure and result of high power RF conditioning, and test and operation results of the upgraded system.  
MOPP092 Efficient Fan-out RF Vector Control Algorithm 766
 
  • Y. W. Kang
    ORNL, Oak Ridge, Tennessee
  
  A new RF vector control algorithm for fan-out power distribution using reactive transmission line circuit parameters for maximum power efficiency is presented. This control with fan-out power distribution system is considered valuable for large scale SRF accelerator systems to reduce construction costs and save on operating costs. Other fixed power splitting systems with individual cavity voltage control at each cavity input may not deliver the power efficiency since excessive power needs to be maintained at each cavity input. In a fan-out RF power distribution system, feeding multiple accelerating cavities with a single RF power generator can be accomplished by adjusting phase delays between the load cavities and reactive loads at the cavity inputs for independent control of cavity RF voltage vectors. In this approach, the RF control parameters for a set of specified cavity RF voltage vectors is determined for a whole fan-out system. The reactive loads and phase shifts can be realized using high power RF phase shifters.  
TUPC125 Status of the Spallation Neutron Source Superconducting RF Facility 1362
 
  • F. Casagrande, S. Assadi, M. T. Crofford, W. R. DeVan, X. Geng, T. W. Hardek, S. Henderson, M. P. Howell, Y. W. Kang, J. Mammosser, W. C. Stone, D. Stout, W. H. Strong, D. C. Williams, P. A. Wright
    ORNL, Oak Ridge, Tennessee
  
  The Spallation Neutron Source (SNS) project was completed without on-site superconducting RF (SRF) facilities. Installation of the infrastructure necessary to maintain and repair the superconducting Linac and to support power upgrade research and development (R&D) is well underway. Installation of a Class10/100/10,000 cleanroom and outfitting of the test cave with RF, vacuum, controls, personnel protection and cryogenics systems is now complete. These systems were recently operated satisfactorily to test a cryomodule that had been removed from the accelerator and repaired in the cleanroom. A horizontal cryostat has been fabricated and will be soon commissioned. Equipment for cryomodule assembly and disassembly has been installed and used for cryomodule disassembly. Cavity processing equipment, specifically an ultra-pure water system, high pressure rinse system, and vertical test area is being designed and installed. This effort is providing both high-power test capability as well as long-term maintenance capabilities. This paper presents the current status and the future plans for the SNS SRF test facility.  
TUPC140 The Spallation Neutron Source Cryomodule Test Stand RF System 1395
 
  • M. T. Crofford, T. W. Hardek, D. Heidenreich, Y. W. Kang, K.-U. Kasemir, S.-H. Kim
    ORNL, Oak Ridge, Tennessee
  • J. A. Ball, T. L. Davidson
    ORNL RAD, Oak Ridge
  
  The Spallation Neutron Source (SNS) has recently commissioned a cryomodule test facility for the repair and testing of the super-conducting cryogenic cavities. This facility utilizes the original 402.5/805 MHz Radio Frequency (RF) Klystron Test Stand as its power source along with dual Low Level RF (LLRF) control systems. One control system is based on the standard SNS Linac LLRF controls with a second system for open-loop only control. The system is designed to allow simultaneous testing of devices in the test cave and other devices which can be tested outside of the enclosure. Initial tests have shown good results; some improvements are yet to be implemented. This paper will provide an overview of the RF systems, safety systems, and interlocks.