Author: Belomestnykh, S.A.
Paper Title Page
MOPFI080 Fabrication, Transport and Characterization of Cesium Potassium Antimonide Cathode in Electron Guns 461
 
  • T. Rao, S.A. Belomestnykh, I. Ben-Zvi, X. Liang, I. Pinayev, B. Sheehy, J. Skaritka, J. Smedley, E. Wang, T. Xin
    BNL, Upton, Long Island, New York, USA
  • R.R. Mammei, J.L. McCarter, M. Poelker
    JLAB, Newport News, Virginia, USA
  • M. Ruiz-Osés
    Stony Brook University, Stony Brook, USA
 
  a number of accelerator applications need high current, low emittance and high brightness electron beams. Recent studies have shown cesium potassium antimonide to be a robust photocathode capable of producing high peak and average currents. However, for some applications, the UHV conditions required for producing these cathodes necessitate their fabrication site to be physically removed from the gun location and the cathode to be transferred between the two sites in UHV load-lock chambers. We have fabricated two cathodes at BNL, transported and tested them in DC gun at JLab at 100 kV and 200 kV. These cathodes have delivered up to 8A/cm2 without significant degradation. Localized changes in the QE have been attributed to heating due to laser, increasing the QE at lower laser power, but damaging the cathode at higher power. Two more load-lock chambers have been built to transport and insert similar cathodes in SRF guns operating at 700 MHz and 112 MHz for the first time. In this paper, we will describe the design of the load-lock chambers, transfer mechanisms, transport of the cathodes over ~ 1000 km and the cathode performance in gun environment.  
 
TUPFI081 Progress with Coherent Electron Cooling Proof-Of-Principle Experiment 1535
 
  • I. Pinayev, S.A. Belomestnykh, I. Ben-Zvi, K.A. Brown, J.C. Brutus, L. DeSanto, A. Elizarov, C. Folz, D.M. Gassner, Y. Hao, R.L. Hulsart, Y.C. Jing, D. Kayran, R.F. Lambiase, V. Litvinenko, G.J. Mahler, M. Mapes, W. Meng, R.J. Michnoff, T.A. Miller, M.G. Minty, P. Orfin, A. Pendzick, F. Randazzo, T. Rao, T. Roser, J. Sandberg, B. Sheehy, J. Skaritka, K.S. Smith, L. Snydstrup, R. Than, R.J. Todd, J.E. Tuozzolo, G. Wang, D. Weiss, M. Wilinski, W. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • G.I. Bell, J.R. Cary, K. Paul, B.T. Schwartz, S.D. Webb
    Tech-X, Boulder, Colorado, USA
  • C.H. Boulware, T.L. Grimm, R. Jecks, N. Miller
    Niowave, Inc., Lansing, Michigan, USA
  • M.A. Kholopov, P. Vobly
    BINP SB RAS, Novosibirsk, Russia
  • M. Poelker
    JLAB, Newport News, Virginia, USA
 
  We conduct proof-of-the-principle experiment of coherent electron cooling (CEC), which has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. In this paper, we present the progress with experimental equipment including the first tests of the electron gun and the magnetic measurements of the wiggler prototype. We describe current design status as well as near future plans.  
 
WEPWO047 A Double Quarter-Wave Deflecting Cavity for the LHC 2408
 
  • R. Calaga
    CERN, Geneva, Switzerland
  • S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, Q. Wu, B. P. Xiao
    BNL, Upton, Long Island, New York, USA
 
  Funding: The HiLumi LHC Design Study (a sub-system of HL-LHC) is cofunded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404
An asymmetric quarter wave deflecting cavity at 400 MHz for crab crossing in the LHC was already proposed in 2011. Due to improved cancellation of on-axis longitudinal field and the higher order components of the deflecting field, a symmetric version is now considered as the baseline for the quarter wave geometry. Relevant RF properties of the symmetric cavity are compared to the original asymmetric cavity. Some aspects of input coupler design, higher order modes, multipacting and frequency tuning are also addressed.
 
 
WEPWO050 Mechanical Study of 400 MHz Double Quarter Wave Crab Cavity for LHC Luminosity Upgrade 2417
 
  • B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, Q. Wu
    BNL, Upton, Long Island, New York, USA
  • L. Alberty Vieira, R. Calaga
    CERN, Geneva, Switzerland
  • T.L. Grimm
    Niowave, Inc., Lansing, Michigan, USA
 
  A prototype double quarter wave crab cavity was designed for the Large Hadron Collider luminosity upgrade. A finite element model is used to simulate the mechanical properties of the crab cavity. The results are presented and a reinforcement concept is proposed to meet the safety requirements. The reinforcement components, as well as the cavity, are presently being fabricated at Niowave Inc.  
 
WEPWO084 Improvement of the Q-factor Measurement in RF Cavities 2489
 
  • W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
 
  Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S.
The Q values of Higher-order-modes (HOMs) in RF cavities are measured at room temperature with the 3 dB bandwidth reading by a network analyzer. The resonant curve distortion is created by the resonance splitting due to the ellipticity caused by manufacture tolerance and RF ports. Therefore, the measured Q values are usually lower than the simulated or theoretical Q values. In some cases, even only one mode’s Q can be measured with the 3 dB method. There may be two reasons for this happening. One is that only one mode was excited and the neighbor splitmode was close to 90° polarized; the other reason is that the resonant curve of one mode was distorted by the other mode too much to measure the 3dB range. In this paper, we resolve this issue by looking into the RF measurement setup, including cavity, input coupler and pick-up coupler, from the equivalent circuit and wave point of view. Based on the BNL3 copper prototype cavity, we compared these results from measurement and simulation.
 
 
WEPWO085 Commissioning SRF Gun for the R&D ERL at BNL 2492
 
  • W. Xu, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, S. Deonarine, D.M. Gassner, H. Hahn, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, L. Masi, G.T. McIntyre, D. Pate, D. Phillips, T. Seda, K.S. Smith, A.N. Steszyn, T.N. Tallerico, R. Than, R.J. Todd, D. Weiss, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi, J. Dai
    Stony Brook University, Stony Brook, USA
 
  Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S.
The R&D ERL project at BNL aims to demonstrate a high charge, high current energy recovery linac. One of the key SRF system is the 704 MHz half-cell SRF gun. The SRF gun is designed to deliver up to 0.5 A beam at 2 MeV with 1 MW of CW RF power. The gun commissioning started in November 2012. The first photoemission beam from the SRF gun is expected in early 2013. This presentation will discuss the results of the SRF gun commissioning, and the performance of the high-power RF system.
 
 
WEPWO086 Split Higher Order Modes in Superconducting Cavities 2495
 
  • H. Hahn, S.A. Belomestnykh, W. Xu
    BNL, Upton, Long Island, New York, USA
 
  Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE and award no. DE-SC0002496 to Stony Brook University with the US DOE.
Split resonances are a common appearance in superconducting cavities and were studied here on the specific example of the TE11 dipole resonance in five-cell copper models of the ERL and BNL3. The BNL3 cavity was designed to be suitable for the envisioned electron-hadron collider eRHIC. Achieving the required high-current performance depends on avoiding beam break-up instabilities by minimizing the Higher Order Modes (HOM) Q-values. This was attempted in the design phase and will be done with appropriate mode dampers in operation. The availability of a copper model provided a convenient opportunity to confirm the design and to study potentially nefarious high-Q resonances. The appearance of split resonances impeded the HOM identification and the theoretical interpretation as elipticity deformation is presented in this report.
 
 
WEPWO084 Improvement of the Q-factor Measurement in RF Cavities 2489
 
  • W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
 
  Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S.
The Q values of Higher-order-modes (HOMs) in RF cavities are measured at room temperature with the 3 dB bandwidth reading by a network analyzer. The resonant curve distortion is created by the resonance splitting due to the ellipticity caused by manufacture tolerance and RF ports. Therefore, the measured Q values are usually lower than the simulated or theoretical Q values. In some cases, even only one mode’s Q can be measured with the 3 dB method. There may be two reasons for this happening. One is that only one mode was excited and the neighbor splitmode was close to 90° polarized; the other reason is that the resonant curve of one mode was distorted by the other mode too much to measure the 3dB range. In this paper, we resolve this issue by looking into the RF measurement setup, including cavity, input coupler and pick-up coupler, from the equivalent circuit and wave point of view. Based on the BNL3 copper prototype cavity, we compared these results from measurement and simulation.
 
 
WEPWO085 Commissioning SRF Gun for the R&D ERL at BNL 2492
 
  • W. Xu, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, S. Deonarine, D.M. Gassner, H. Hahn, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, L. Masi, G.T. McIntyre, D. Pate, D. Phillips, T. Seda, K.S. Smith, A.N. Steszyn, T.N. Tallerico, R. Than, R.J. Todd, D. Weiss, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi, J. Dai
    Stony Brook University, Stony Brook, USA
 
  Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S.
The R&D ERL project at BNL aims to demonstrate a high charge, high current energy recovery linac. One of the key SRF system is the 704 MHz half-cell SRF gun. The SRF gun is designed to deliver up to 0.5 A beam at 2 MeV with 1 MW of CW RF power. The gun commissioning started in November 2012. The first photoemission beam from the SRF gun is expected in early 2013. This presentation will discuss the results of the SRF gun commissioning, and the performance of the high-power RF system.