Author: Eichhorn, R.
Paper Title Page
WEPWO059 Cornell's HOM Beamline Absorbers 2441
  • R. Eichhorn, J.V. Conway, Y. He, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, P. Quigley, J. Sears, V.D. Shemelin, N.R.A. Valles
    CLASSE, Ithaca, New York, USA
  The proposed energy recovery linac at Cornell aims for high beam currents and short bunch lengths, the combination of which requires efficient damping of the higher order modes (HOMs) being present in the superconducting cavities. Numerical simulations show that the expected HOM power could be as high as 200 W per cavity with frequencies ranging to 40 GHz. Consequently, a beam line absorber approach was chosen. We will review the design, report on first results from a prototype and discuss further improvements.  
WEPWO060 The CW Linac Cryo-module for Cornell’s ERL 2444
  • R. Eichhorn, Y. He, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
    CLASSE, Ithaca, New York, USA
  Cornell University has proposed an energy-recovery linac (ERL) based synchrotron-light facility which can provide greatly improved X-ray beams due to the high electron-beam quality that is available from a linac. As part of the phase 1 R&D program, critical challenges in the design were addressed, one of them being a full linac cryo-module. It houses 6 superconducting cavities- operated at 1.8 K in cw mode- HOM absorbers and a magnet/ BPM section. We will present the design being finalized recently and report on the fabrication status that started in late 2012.  
WEPWO061 Readiness for the Cornell ERL 2447
  • G.H. Hoffstaetter, A.C. Bartnik, I.V. Bazarov, D.H. Bilderback, M.G. Billing, J.D. Brock, J.A. Crittenden, L. Cultrera, D.S. Dale, J. Dobbins, B.M. Dunham, R.D. Ehrlich, M. P. Ehrlichman, R. Eichhorn, K. Finkelstein, E. Fontes, M.J. Forster, S.J. Full, F. Furuta, D. Gonnella, S.W. Gray, S.M. Gruner, C.M. Gulliford, D.L. Hartill, Y. He, R.G. Helmke, K.M.V. Ho, R.P.K. Kaplan, S.S. Karkare, V.O. Kostroun, H. Lee, Y. Li, M. Liepe, X. Liu, J.M. Maxson, C.E. Mayes, A.A. Mikhailichenko, H. Padamsee, J.R. Patterson, S.B. Peck, S. Posen, P. Quigley, P. Revesz, D.H. Rice, D. Sagan, J. Sears, V.D. Shemelin, D.M. Smilgies, E.N. Smith, K.W. Smolenski, A.B. Temnykh, M. Tigner, N.R.A. Valles, V. Veshcherevich, A.R. Woll, Y. Xie, Z. Zhao
    CLASSE, Ithaca, New York, USA
  Funding: Supported by NSF award DMR-0807731 and NY State
Energy-Recovery Linacs (ERLs) are proposed as drivers for hard x-ray sources because of their ability to produce electron bunches with small, flexible cross sections and short lengths at high repetition rates. Cornell University has pioneered the design and hardware for ERL lightsources. This preparatory research for ERL-lightsource construction will be discussed. Important milestones have been achieved in Cornell's prototype ERL injector, including the production of a prototype SRF cavity that exceeds design specifications, the regular production of long-lived and low emittance cathodes, the acceleration of ultra-low emittance bunches, and the world-record of 65 mA current from a photoemission DC gun. We believe that demonstration of the practical feasibility of these technologies have progressed sufficiently to allow the construction of an ERL-based lightsource like that described in [].
WEPWO066 Frequency Control in the Cornell-ERL Main-Linac Cavity Production 2453
  • V.D. Shemelin, B. Bullock, P.R. Carriere, B. Clasby, R. Eichhorn, B. Elmore, J.J. Kaufman, J. Sears
    CLASSE, Ithaca, New York, USA
  Funding: NSF award DMR-0807731
Cavity fabrication can be broken down into three main stages: deep-drawing cups, welding the cups in pairs to obtain “dumbbells” and end groups, and, finally, welding the obtained components into a completed cavity. Frequency measurements and precise machining were implemented after the second stage. A custom RF fixture and data acquisition system were used for this purpose. The system comprised of a mechanical press with RF contacts, a network analyzer, a load cell and custom LabVIEW and MATLAB scripts. To extract the individual frequencies of the cups from these measurements, algorithm of calculations was developed. Corrections for the ambient environment were also incorporated into the measurement protocol. Two 7-cell 1.3 GHz cavities were produced with high field flatness immediately after fabrication.
WEPWO068 Cornell ERL Main Linac 7-cell Cavity Performance in Horizontal Test Cryomodule Qualifications 2459
  • N.R.A. Valles, R. Eichhorn, F. Furuta, G.M. Ge, D. Gonnella, Y. He, K.M.V. Ho, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, S. Posen, P. Quigley, J. Sears, V. Veshcherevich
    CLASSE, Ithaca, New York, USA
  Funding: NSF DMR-0807731
Cornell has recently finished producing and testing the first prototype 7-cell main linac cavity for the Cornell Energy Recovery Linac, and completed the prototype cavity qualification program. This paper presents quality factor results from the horizontal test cryomodule (HTC) measurements, from the HTC-1 through HTC-3 experiments, reaching Q's up to 6 x 1010 at 1.6 K. We investigate the effect of thermal cycling on cavity quality factor and show that high quality factors can be preserved from initial mounting to fully outfitting the cavity with side-mounted input coupler and beam line absorbers. We also discuss the production of six additional main-linac cavities as we progress toward constructing a full 6-cavity cryomodule.
WEPWO069 HOM Studies of the Cornell ERL Main Linac Cavity: HTC-1 Through HTC-3 2462
  • N.R.A. Valles, R. Eichhorn, G.H. Hoffstaetter, M. Liepe
    CLASSE, Ithaca, New York, USA
  Funding: Supported by NSF grant DMR-0807731
The Cornell energy recovery linac is designed to run a high energy (5 GeV), high current (100 mA), very low emittance beam (30 pm at 77 pC bunch charge). A major challenge to running such a large current continuously through the machine is the effect of strong higher-order modes(HOMs) that can lead to beam breakup. This paper presents the results of HOM studies for the prototype 7-cell cavity installed in a horizontal test cryomodule (HTC) from initial RF test, to being fully outfitted with side-mounted input coupler and beam line absorbers. We compare the simulated results of the optimized cavity geometry with measurements from all three HTC experiments.
WEPFI076 Experience with a 5 kW, 1.3 GHz Solid State Amplifier 2869
  • K.M.V. Ho, R. Eichhorn, D.L. Hartill, M. Liepe
    CLASSE, Ithaca, New York, USA
  This study describes the experience with and performance of a commercially available 1.3 GHz 5kW Solid State Amplifier in various experiments at Cornell University. This paper focuses on several key factors in testing the performance of the amplifier. Among those are phase and amplitude stability, gain linearity, and phase shift vs. power. High power amplifiers are usually built with multiple RF power modules and the individual output signals are then combined in a power combiner. Therefore, the phases of the individual RF output power signals have to be adjusted within tight tolerances. The relative phases can be affected by different lengths cables and also affect the overall gain performance of the amplifier.  
THPFI007 Increasing the Stability of the Electron Beam of the S-DALINAC 3303
  • F. Hug, T. Bahlo, C. Burandt, J. Conrad, L.E. Jürgensen, M. Kleinmann, M. Konrad, T. Kürzeder, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • R. Eichhorn
    CLASSE, Ithaca, New York, USA
  Funding: Funded by DFG through SFB 634
The S-DALINAC is a superconducting recirculating electron accelerator with a final energy of 130 MeV. It operates in cw at 3 GHz. It accelerates beams of either unpolarized or polarized electrons and is used as a source for nuclear- and astrophysical experiments at the university of Darmstadt since 1987. We will report on two future upgrade plans for increasing the operation stability of the accelerator: A high energy scraper system for collimating the beam before it is delivered to the experiments and a rf feedback system to fix the rf phase of the beam leaving the injector linac by measurements on a rf monitor.
WEPME005 Pulsed RF Control for the P-Linac Test Stand at FAIR 2929
  • P. Nonn, U. Bonnes, C. Burandt, F. Hug, M. Konrad, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • R. Eichhorn
    Cornell University, Ithaca, New York, USA
  • H. Klingbeil, G. Schreiber, W. Vinzenz
    GSI, Darmstadt, Germany
  • H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  Funding: Supported through BMBF contract no. 06DA9024I
The p-linac will be a dedicated proton injector for antiproton production at FAIR (GSI Darmstadt). It will provide a 70 MeV/70 mA pulsed proton beam with a duty cycle of about 10-4. Therefore the RF of the normal conducting, coupled CH cavities* will be pulsed, too. In order to test the operation of those cavities, a test stand is under construction at GSI. The RF control hard- and software for the test stand is developed at TU Darmstadt. It is based on the digital low level RF control system, which is operational at the S-DALINAC**. Hardware as well as software had to be customized, in order to achieve pulsed operation within the given limits. These customizations as well as measurements from pulsed operation will be presented.
*R. Brodhage et al. Development and Measurements on a Coupled CH Proton Linac for FAIR, IPAC'10
**M. Konrad et al. Digital base band rf control system for the… , PRL ST Accel. & Beams 15