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Performance experience with the CEBAF SRF cavities

Description: The full complement of 169 pairs of niobium superconducting cavities has been installed in the CEBAF accelerator. This paper surveys the performance characteristics of these cavities in vertical tests, commissioning in the tunnel, and operational experience to date. Although installed performance exceeds specifications, and 3.2 GeV beam has been delivered on target, present systems do not consistently preserve the high performance obtained in vertical dewar tests as operational capability. Prin… more
Date: December 31, 1995
Creator: Reece, C.; Benesch, J.; Drury, M.; Hovater, C.; Mammosser, J. & Preble, J.
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Partner: UNT Libraries Government Documents Department
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Preliminary Statistical Analysis of CEBAF's Cavity Pair Assembly Process Data

Description: CEBAF has been collecting much data during the cavity pair assembly process. Some process data has been entered and analyzed during the last two years as part of our attempt to apply statistical process control methods. Analysis is presented here on mechanical tolerances achieved by the industrial fabricator of the CEBAF superconducting rf cavities (Siemens). Suggestions for tolerances obtainable in future procurements are made. Influence of cooldown conditions during vertical test on field emi… more
Date: December 1, 1993
Creator: Benesch, Jay
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Study of Higher Order Modes in High Current Multicell SRF Cavities.

Description: The electron cooling project for RHIC luminosity upgrade and future projects such as eRHIC (electron-ion collider) demand cavities operating at high average current and high bunch charge in CW energy recovery mode. This paper describes the investigation of Higher Order Modes (HOMs) in such a cavity. This work is part of an ongoing effort to develop a 5-cell superconducting cavity for such high current and high bunch charge energy-recovery superconducting linac. The frequency of the cavity is 70… more
Date: September 8, 2003
Creator: Calaga, R.; Ben-Zvi, Ilan; Zhao, Y.; Wang, D. & Wu, G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Arcing phenomena on CEBAF RF-windows at cryogenic temperatures

Description: During the CEBAF commissioning tests some of the superconducting cavities had light emitting discharges (arcing) which were observed in the guard vacuum space between a warm polymeric rf window and the cold ceramic rf window. A dedicated off-line test system was implemented to investigate the conditions under which arcing may occur and to gain some understanding of the mechanisms leading to this phenomenon through optical spectral analysis. This paper reports on the photoemission spectra observ… more
Date: December 31, 1995
Creator: Powers, T.; Kneisel, P. & Allen, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Tests of a prototype magnetostrictive tuner for superconducting cavities

Description: The Continuous Electron Beam Accelerator (CEBA) uses mechanical tuners at 2 K driven by room temperature stepping motors in a feedback loop to maintain cavity frequency at 1497 MHz. Modification of the system was designed, replacing a passive section of the mechanical tuner with a magnetostrictive tuning element consisting of a Ni rod and an industrially supplied 0.25 T superconducting solenoid. This assembly was tested with several magnetic shield configurations designed to keep the stray flux… more
Date: October 1, 1996
Creator: Benesch, J.F. & Wiseman, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Superconducting heavy-ion accelerating structures

Description: This paper briefly reviews the technical history of superconducting ion-accelerating structures. Various superconducting cavities currently used and being developed for use in ion linacs are discussed. Principal parameters and operational characteristics of superconducting structures in active use at various heavy-ion facilities are described.
Date: August 1, 1996
Creator: Shepard, K.W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Development of niobium spoke cavities for a superconducting light-ion linac

Description: This paper reports the development of 350 MHz niobium superconducting cavities for the velocity range 0.2 < v/c < 0.6. Such cavities could be used to form a linac of exceptional flexibility, capable of efficiently accelerating beams of either protons, deuterons, or any of a wide range of ions, at intensities sufficient for a production beam for a radioactive facility. Results of numerical modeling for several resonator geometries are presented. The design and construction status of protot… more
Date: August 1, 1998
Creator: Shepard, K.W.; Kedzie, M.; Delayen, J.R. & Piller, C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Phasing schemes for CEBAF cavities

Description: The CEBAF accelerator requires accurate phasing of the 338 superconducting cavities to achieve the design rms energy spread of 2.5 X 10{sup {minus}5}. The rms phase error along each linac, with 160 cavities over a length of 200 m, may not exceed 2.6 degrees, assuming that the whole linac is operated on crest. The common procedure is to maximize the energy gain with a spectrometer. At CEBAF, however, phase-dependent cavity steering effects cause deflections of the beam of several mrad, requiring… more
Date: May 1993
Creator: Simrock, S.; Kazimi, R.; Krafft, G.; Mermings, L.; Ninan, L. & Witherspoon, S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A beat frequency buncher

Description: A superconducting high energy buncher operating at 13/12 times the linac frequency has been built and installed, to combine with the low energy buncher operating at 1/12 the linac frequency. The system is synchronized so the linac and high energy buncher beat frequency remains in phase with the low energy buncher. On linac cycles not corresponding to a primary bunch, the high energy buncher bunches residual beam away from the linac longitudinal acceptance rather than into it. The resonator for … more
Date: September 1, 1995
Creator: Storm, D.W.; Corcoran, D.T. & Harper, G.C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Design considerations for high-current superconducting ion linacs

Description: Superconducting linacs may be a viable option for high-current applications such as fusion materials irradiation testing, spallation neutron source, transmutation of radioactive waste, tritium production, and energy production. These linacs must run reliably for many years and allow easy routine maintenance. Superconducting cavities operate efficiently with high cw gradients, properties which help to reduce operating and capital costs, respectively. However, cost-effectiveness is not the sole c… more
Date: August 1, 1993
Creator: Delayen, J. R.; Bohn, C. L.; Micklich, B. J.; Roche, C. T. & Sagalovsky, L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Progress in cavity and cryomodule design for the Project X linac

Description: The continuous wave 3 GeV Project X Linac requires the development of two families of cavities and cryomodules at 325 and 650 MHz. The baseline design calls for three types of superconducting single-spoke resonators at 325 MHz having betas of 0.11, 0.22, and 0.42 and two types of superconducting five-cell elliptical cavities having betas of 0.61 and 0.9. These cavities shall accelerate a 1 mA H- beam initially and must support eventual operation at 4 mA. The electromagnetic and mechanical desig… more
Date: March 1, 2011
Creator: Champion, M.; Barbanotti, S.; Foley, M.; Ginsburg, S.; Gonin, I; Grimm, C. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Concept em design of the 650 MHz cavities for the Project X

Description: Concept of the 650 MHz cavities for the Project X is presented. Choice of the basic parameters, i.e., number of cells, geometrical {beta}, apertures, coupling coefficients, etc., is discussed. The cavity optimization criteria are formulated. Results of the RF design are presented for the cavities of both the low-energy and high-energy sections.
Date: March 1, 2011
Creator: Yakovlev, V.; Champion, M.; Gonin, I.; Lunin, A.; Kazakov, S.; Khabiboulline, T. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Buffer Chemical Polishing and RF Testing of the 56 MHz SRF Cavity

Description: The 56 MHz cavity presents a unique challenge in preparing it for RF testing prior to construction of the cryomodule. This challenge arises due to the physical dimensions and subsequent weight of the cavity, and is further complicated by the coaxial geometry, and the need to properly chemically etch and high pressure rinse the entire inner surface prior to RF testing. To the best of my knowledge, this is the largest all niobium SRF cavity to be chemically etched and subsequently tested in a ver… more
Date: January 1, 2009
Creator: Burrill,A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Wakefield calculation for superconducting TM110 cavity without azimuthal symmetry

Description: The 3.9GHz TM{sub 110} mode deflecting cavity developed at FNAL has many applications, including use as a longitudinal bunch profile diagnostic, and as a crab cavity candidate for the ILC. These applications involve beams with substantial time structure. For the 13-cell version intended for the bunch profile application, long-range wakes have been evaluated in the frequency domain and short-range wakes have been evaluated in the time domain. Higher-order interactions of the main field in the ca… more
Date: August 1, 2006
Creator: Bellantoni, Leo & Burt, Graeme
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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An rf separated kaon beam from the Main Injector: Superconducting aspects

Description: ThE report is intended to focus on the superconducting aspects of a potential separated kaon beam facility for the Main Injector, and most of this document reflects that emphasis. However, the RF features cannot be divorced from the overall beam requirements, and so the next section is devoted to the latter subject. The existing optics design that meets the needs of the two proposed experiments is outliied, and its layout at Fermilab is shown. The frequency and deflection gradient choices prese… more
Date: November 1, 1998
Creator: Edwards, D. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Beam test of a superconducting cavity for the Fermilab high-brightness electron photo-injector

Description: An electron photo-injector facility has been constructed at Fermilab for the purpose of providing a 14�18 MeV elec-tron beam with high charge per bunch (8 nC), short bunch length (1 mm RMS), and small transverse emittance [1]. The facility was used to commission a second-generation photo-cathode RF gun for the TeSLA Test Facility (TTF) Linac at DESY [2, 3]; in the future, the Fermilab electron beam will be used for R & D in bunch length compres-sion, beam diagnostics, and new acceleration techn… more
Date: May 4, 1999
Creator: W. Hartung, J.P. Carneiro, M. Champion, H. Edwards, J. Fuest, K. Koepke and M. Kuchnir
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Operational monitoring of the CEBAF RF system

Description: An EPICS-based control interface has been developed which enables effective monitoring of the 338 independent RF systems that drive CEBAF`s superconducting cavities. Visual screens allow the operator to quickly identify cavities that have faulted, or which are operating out of specification. These screens allow the operator easy access to automated routines for clearing faults, routines for documenting and tracking hardware problems, and expert screens for immediate correction of RF problems. T… more
Date: December 31, 1995
Creator: Karn, J.; Dunham, B. & Tiefenback, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Summary on the Fundamental Mode Damper Experiments of the 56 MHz SRF Cavity

Description: This report summarizes the experimental results done with the fundamental damper for the 56 MHz prototype Cu cavity. Various measurements were done on the cavity including determination of the position of the fundamental damper and measurement of the frequency and Q factor changes while the damper is withdrawn. Prediction on the dissipated power while the damper is withdrawn was made by experiments.
Date: July 1, 2008
Creator: Choi,E. & Hahn, H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Improvement of the operational performance of SRF cavities via in situ helium processing and waveguide vacuum processing

Description: The useful performance range of the superconducting rf (SRF) cavities in the CEBAF accelerator at Jefferson Lab is frequently limited by electron field emission and derived phenomena. Improvements are required to support future operation of the accelerator at higher than 5 GeV. Twelve operational cryomodules have been successfully processed to higher useful operating gradients via rf-helium processing. Progress against field emission was evidenced by improved high-field Q, reduced x-ray product… more
Date: June 1, 1997
Creator: Reece, C.E.; Drury, M.; Rao, M.G. & Nguyen-Tuong, V.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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