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THP019 Commissioning of the Digital LLRF for the CEBAF Injector/Separator controls, feedback, linac, instrumentation 607
 
  • T. E. Plawski, H. Dong, C. Hovater, K. King, G. E. Lahti, J. Musson
    Jefferson Lab, Newport News, Virginia
  The design and production of the CEBAF accelerator 499 MHz digital Low-Level RF control system has been completed. The first five systems were installed for use with the CEBAF Separator RF deflecting cavities operating at 499 MHz. The next four systems were installed in the injector on the chopping cavities (also 499 MHz deflecting cavities). The new LLRF system replaced an analog system that was over 15 years old. For initial testing an extensive acceptance plan along with a LLRF test stand was developed and incorporated to assure system performance as well as reliability. Various VHDL firmware was developed and modified to support operation of this system and included specific operational diagnostics. Once the acceptance tests were completed, the new systems were installed in the accelerator, in parallel with the existing analog LLRF, for extensive in-situ testing and comparison. After system commissioning, the new RF systems were assigned to the CEBAF accelerator and turned over to Accelerator Operations. This paper will address the VHDL firmware evolution, the automated tests and the performance measurements made through out the installation and commissioning process.  
 
THP049 LANSCE DTL Longitudinal Field Measurements at High Power resonance, linac, proton, acceleration 691
 
  • G. O. Bolme, S. Archuletta, J. Davis, L. Lopez, J. T.M. Lyles, D. J. Vigil
    LANL, Los Alamos, New Mexico
  Shifts in proton beam tuning were observed in the DTL portion of the Los Alamos Neutron Science Center (LANSCE) Accelerator corresponding with cooling system obstructions during the 2003 operational cycle. A diagnostic system was developed to measure longitudinal field changes at the operational field levels to confirm the source of the tune shifts and track the effectiveness of cooling system repairs. This paper describes the diagnostic system and the results of field distribution measurements at high RF power in the accelerating structures.  
 
THP068 RF Characteristics of the SDTL for the J-PARC linac, proton, synchrotron, target 740
 
  • T. Ito, H. Asano, T. Morishita
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • T. Kato, F. Naito, E. Takasaki, H. Tanaka
    KEK, Ibaraki
  For the J-PARC linac, a Separated type DTL (SDTL) is used to accelerate an H- ion beam from 50MeV to 191MeV. The SDTL consists of 32 tanks and the operating frequency is 324MHz. It has 4 drift tubes and 2 half tubes (5cells), 2 fix tuners, 1 movable tuner and 1 RF input coupler. The inner diameter is 520mm and the length is approximately from 1.5m (SDTL1) to 2.5m (SDTL32). The focusing magnets are set between the tanks. We have measured the RF characteristics of the SDTL tanks and adjusted the field distribution since last summer. The measured Q value was above 90% of ideal SUPERFIS value, the field distribution was adjusted within ±1% for all the tanks. In this paper, the results of RF measurements of the SDTL tanks are described.  
 
THP090 Initial Studies of 9-Cell High-Gradient Superconducting Cavities at KEK pick-up, superconductivity, coupling, higher-order-mode 794
 
  • T. Saeki, F. Furuta, H. Hayano, Y. Higashi, T. Higo, I. H. Inoue, S. Kazakov, H. Matsumoto, Y. Morozumi, R. S. Orr, K. Saito, M. Satoh, N. Toge, K. Ueno, H. Yamaoka, K. Yokoya
    KEK, Ibaraki
  Vertical tests of single cell cavities of the KEK Low Loss "Ichiro" design have established that gradients as high as 51 MV/m are feasible in principle. We have also performed vertical tests of 9-cell cavities. The internal surface was prepared according to the prescription developed in the single cell series test. In this paper we report results on the accelerating gradients achieved so far, an investigation of the possible presence of hydrogen "Q Disease," and other high-field related studies. We also present the measurement of the higher modes of the cavities.