Author: Hahn, H.
Paper Title Page
TUP052 HOM Damping Properties of Fundamental Power Couplers in the Superconducting Electron Gun of the Energy Recovery LINAC at Brookhaven National Laboratory 901
 
  • L.R. Hammons, H. Hahn
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Among the accelerator projects under construction at the Relativistic Heavy Ion Collider (RHIC) is an R&D energy recovery LINAC (ERL) test facility. The ERL includes both a five-cell superconducting cavity as well as a superconducting, photoinjector electron gun. Because of the high-charge and high-current demands, effective higher-order mode (HOM) damping is essential, and several strategies are being pursued. Among these is the use of the fundamental power couplers as a means for damping some HOMs. Simulation studies have shown that the power couplers can play a substantial role in damping certain HOMs, and this presentation will discuss these studies along with measurements.
 
 
TUP053 Ferrite HOM Load Surrounding a Ceramic Break 904
 
  • L.R. Hammons, H. Hahn
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Several future accelerator projects at the Relativistic Heavy Ion Collider are being developed using a super-conducting electron energy recovery LINAC along with a superconducting electron gun as the source. All of the projects involve high-current, high-charge operation and require effective higher-order mode (HOM) damping to achieve the performance objectives. Among the HOM designs being developed is a waveguide-type HOM load for the electron gun consisting of a ceramic break surrounded by ferrite tiles. This design is innovative in its approach and achieves a variety of ends including broadband HOM damping and protection of the superconducting cavity from potential damage to the ferrite tiles. Furthermore, the ceramic is an effective thermal transition. This design may be useful in various applications since it readily allows for replacement of the ferrite tiles with other materials and may also be useful for testing the absorbing properties of these materials. In this paper, the details of the design will be discussed along with current modelling and testing results as well as future plans.
 
 
TUP056 BNL 703 MHz Superconducting RF Cavity Testing 913
 
  • B. Sheehy, Z. Altinbas, I. Ben-Zvi, D.M. Gassner, H. Hahn, L.R. Hammons, J.P. Jamilkowski, D. Kayran, J. Kewisch, N. Laloudakis, D.L. Lederle, V. Litvinenko, G.T. McIntyre, D. Pate, D. Phillips, C. Schultheiss, T. Seda, R. Than, W. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • A. Burrill
    JLAB, Newport News, Virginia, USA
  • T. Schultheiss
    AES, Medford, NY, USA
 
  Funding: This work received support from Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The Brookhaven National Laboratory (BNL) 5-cell, 703 MHz superconducting RF accelerating cavity has been installed in the high-current energy recovery linac (ERL) experiment. This experiment will function as a proving ground for the development of high-current machines in general and is particularly targeted at beam development for an electron-ion collider (eRHIC). The cavity performed well in vertical tests, demonstrating gradients of 20 MV/m and a Q0 of 1010. Here we will present its performance in the horizontal tests, and discuss technical issues involved in its implementation in the ERL.
 
 
TUP060 New HOM Coupler Design for High Current SRF Cavity 925
 
  • W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn, E.C. Johnson
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Damping higher order modes (HOMs) significantly to avoid beam instability is a challenge for the high current Energy Recovery Linac-based eRHIC at BNL. To avoid the overheating effect and high tuning sensitivity, current, a new band-stop HOM coupler is being designed at BNL. The new HOM coupler has a bandwidth of tens of MHz to reject the fundamental mode, which will avoid overheating due to fundamental frequency shifting because of cooling down. In addition, the S21 parameter of the band-pass filter is nearly flat from first higher order mode to 5 times the fundamental frequency. The simulation results showed that the new couplers effectively damp HOMs for the eRHIC cavity with enlarged beam tube diameter and two 120° HOM couplers at each side of cavity. This paper presents the design of HOM coupler, HOM damping capacity for eRHIC cavity and prototype test results.
 
 
TUP213 Research and Development toward the RHIC Injection Kicker Upgrade 1211
 
  • W. Zhang, W. Fischer, H. Hahn, C. Pai, J. Sandberg, J.E. Tuozzolo
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A research and development work is on going toward the upgrade of the RHIC Injection Fast Kicker System. We report here the proposed nano-second pulse generator, the initial test result, the options of the deflector design, injection pattern, and the benefit to the future RHIC programs.
 
 
WEP177 Radial Transmission Line Analysis of Multi-layer Circular Structures 1819
 
  • H. Hahn, L.R. Hammons
    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.
The analysis of multi-layer beam tubes is a frequent problem and is usually solved with axially propagating waves. This treatment is ill suited to a short multi-layer structure such as the present example of a ferrite covered ceramic break in the beam tube at the ERL photo-cathode electron gun. This paper demonstrates that such structures can better be treated by radial wave propagation. The theoretical method is presented and numerical results are compared with measured network analyser data and Microwave Studio generated simulations. The results confirm the concept of radial transmission lines as a valid analytical method.
 
 
THP006 Status of High Current R&D Energy Recovery Linac at Brookhaven National Laboratory 2148
 
  • D. Kayran, Z. Altinbas, D.R. Beavis, I. Ben-Zvi, R. Calaga, D.M. Gassner, H. Hahn, L.R. Hammons, A.K. Jain, J.P. Jamilkowski, N. Laloudakis, R.F. Lambiase, D.L. Lederle, V. Litvinenko, G.J. Mahler, G.T. McIntyre, W. Meng, B. Oerter, D. Pate, D. Phillips, J. Reich, T. Roser, C. Schultheiss, B. Sheehy, T. Srinivasan-Rao, R. Than, J.E. Tuozzolo, D. Weiss, W. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
 
  An ampere-class 20 MeV superconducting energy recovery linac (ERL) is under construction at Brookhaven National Laboratory (BNL) for testing of concepts relevant for high-energy coherent electron cooling and electron-ion colliders. One of the goals is to demonstrate an electron beam with high charge per bunch (~5 nC) and low normalized emittance (~5 mm-mrad) at an energy of 20 MeV. A flexible lattice for the ERL loop provides a test bed for investigating issues of transverse and longitudinal instabilities and diagnostics for CW beam. A superconducting 703 MHz RF photo-injector is considered as an electron source for such a facility. We will start with a straight pass (gun/cavity/beam stop) test for gun performance studies. Later, we will install and test a novel injection line concept for emittance preservation in a lower-energy merger. Here we present the status and our plans for construction and commissioning of this facility.  
 
THP108 Analysis of RHIC Beam Dump Pre-fires 2327
 
  • W. Zhang, L. A. Ahrens, W. Fischer, H. Hahn, J.-L. Mi, J. Sandberg, Y. Tan
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
It has been speculated that the beam may cause instability of the RHIC Beam Abort Kickers. In this study, we explore the available data of past beam operations, the device history of key modulator components, and the radiation patterns to examine the correlations.
 
 
FROBS6 High Current SRF Cavity Design for SPL and eRHIC 2589
 
  • W. Xu, I. Ben-Zvi, R. Calaga, H. Hahn, E.C. Johnson, J. Kewisch
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
In order to meet the requirements of high average current accelerators, such as the Superconducting Proton Linac (SPL) at CERN and the electron–ion collider (eRHIC) at BNL, a high current 5-cell SRF cavity, called BNL3 cavity, was designed. The optimization process aimed at maximizing the R/Q of the fundamental mode and the geometry factor G under an acceptable RF field level of Bpeak/Eacc or Epeak/Eacc. In addition, a pivotal consideration for the high current accelerators is efficient damping of dangerous higher-order modes (HOM) to avoid inducing emittance degradation, cryogenic loading or beam-breakup (BBU). To transport the HOMs out of the cavity, the BNL3 cavity employs a larger beam pipe, allowing the propagation of HOMs but not the fundamental mode. Moreover, concerning the BBU effect, the BNL3 cavity is aimed at low (R/Q)Qext for dangerous modes, including dipole modes and quadrupole modes. This paper presents the design of the BNL3 cavity, including the optimization for the fundamental mode, and the BBU limitation for dipole and quadrupole modes. The BBU simulation results show that the designed cavity is qualified for high-current, multi-pass machines such as eRHIC.
 
slides icon Slides FROBS6 [2.577 MB]  
 
TUOAN2 High Luminosity Electron-Hadron Collider eRHIC 693
 
  • V. Ptitsyn, E.C. Aschenauer, M. Bai, J. Beebe-Wang, S.A. Belomestnykh, I. Ben-Zvi, M. Blaskiewicz, R. Calaga, X. Chang, A.V. Fedotov, H. Hahn, L.R. Hammons, Y. Hao, P. He, W.A. Jackson, A.K. Jain, E.C. Johnson, D. Kayran, J. Kewisch, V. Litvinenko, G.J. Mahler, G.T. McIntyre, W. Meng, M.G. Minty, B. Parker, A.I. Pikin, T. Rao, T. Roser, B. Sheehy, J. Skaritka, S. Tepikian, R. Than, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, Q. Wu, W. Xu, A. Zelenski
    BNL, Upton, Long Island, New York, USA
  • E. Pozdeyev
    FRIB, East Lansing, Michigan, USA
  • E. Tsentalovich
    MIT, Middleton, Massachusetts, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We present the design of future high-energy high-luminosity electron-hadron collider at RHIC called eRHIC. We plan on adding 20 (potentially 30) GeV energy recovery linacs to accelerate and to collide polarized and unpolarized electrons with hadrons in RHIC. The center-of-mass energy of eRHIC will range from 30 to 200 GeV. The luminosity exceeding 1034 cm-2 s-1 can be achieved in eRHIC using the low-beta interaction region with a 10 mrad crab crossing. We report on the progress of important eRHIC R&D such as the high-current polarized electron source, the coherent electron cooling and the compact magnets for recirculating passes. A natural staging scenario of step-by-step increases of the electron beam energy by builiding-up of eRHIC's SRF linacs and a potential of adding polarized positrons are also presented.
 
slides icon Slides TUOAN2 [4.244 MB]  
 
FROAN1 The European Spallation Source 2549
 
  • S. Peggs, H. Danared, M. Eshraqi, H. Hahn, A. Jansson, M. Lindroos, A. Ponton, K. Rathsman, G. Trahern
    ESS, Lund, Sweden
  • S. Bousson
    IPN, Orsay, France
  • R. Calaga
    BNL, Upton, Long Island, New York, USA
  • G. Devanz, R.D. Duperrier
    CEA/DSM/IRFU, France
  • J. Eguia
    Fundación TEKNIKER, Eibar (Gipuzkoa), Spain
  • S. Gammino
    INFN/LNS, Catania, Italy
  • S.P. Møller
    ISA, Aarhus, Denmark
  • C. Oyon
    SPRI, Bilbao, Spain
  • R.J.M.Y. Ruber
    Uppsala University, Uppsala, Sweden
  • T. Satogata
    JLAB, Newport News, Virginia, USA
 
  The European Spallation Source (ESS) is a 5 MW, 2.5 GeV long pulse proton linac, to be built and commissioned in Lund, Sweden. The Accelerator Design Update (ADU) project phase is under way, to be completed at the end of 2012 by the delivery of a Technical Design Report. Improvements to the 2003 ESS design will be summarised, and the latest design activities will be presented.  
slides icon Slides FROAN1 [1.650 MB]