MOZBB —  Monday Parallel Session 4   (02-Sep-19   14:00—16:00)
Chair: P. Muggli, MPI, Muenchen, Germany
Paper Title Page
Beam Dynamics in Structure-Based Beam-Driven Accelerators  
  • S. Baturin
    Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
  Funding: U.S. National Science Foundation under Grant No. PHY- 1549132, the Center for Bright Beams and under Grant No. PHY-1535639
Structure-based beam-driven acceleration scheme still lacks an understanding of many aspects, such as beam stability, energy transfer efficiency. This talk will be focused on analytical methods and simple mathematical models to address these remaining challenges and gain detailed insight into important effects in beam-driven acceleration schemes.
S. Baturin, et al., Phys. Rev. Accel. Beams 21(3), 031301 (2018)
S. Baturin, et al., arXiv:1807.10708 [physics.acc-ph]
S. Baturin, et al., Phys. Rev. Lett. 113, 214801 (2014).
MOZBB2 Experiments with Metamaterial-Based Metallic Accelerating Structures -1
MOPLH20   use link to see paper's listing under its alternate paper code  
  • X. Lu
    SLAC, Menlo Park, California, USA
  • M.E. Conde, D.S. Doran, G. Ha, J.G. Power, J.H. Shao, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • X. Lu, I. Mastovsky, J.F. Picard, M.A. Shapiro, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
  • M.M. Peng
    AAI/ANL, Lemont, Illinois, USA
  • J. Seok
    UNIST, Ulsan, Republic of Korea
  Funding: U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award No. DE-SC0015566 at MIT and No. DE-AC02-06CH11357 at ANL
We present experimental studies of metamaterial (MTM) structures for wakefield acceleration. The MTM structure is an all-metal periodic structure with its period much smaller than the wavelength at X-band. The fundamental TM mode has a negative group velocity, so an electron beam traveling through the structure radiates by reversed Cherenkov radiation. Two experiments have been completed at the Argonne Wakefield Accelerator (AWA), namely the Stage-I and Stage-II experiments. Differences between the two experiments include: (1) Structure length (Stage-I 8 cm, Stage-II 20 cm); (2) Bunch number used to excite the structure (Stage-I up to 2 bunches, Stage-II up to 8 bunches). In the Stage-I experiment, two bunches with a total charge of 85 nC generated 80 MW of RF power in a 2 ns long pulse. In the Stage-II experiment, the highest peak power reached 380 MW in a 10 ns long pulse from a train of 8 bunches with a total charge of 224 nC. Acceleration of a witness bunch has not been demonstrated yet, but the extracted power can be transferred to a separate accelerator for two-beam acceleration or directly applied to a trailing witness bunch in the same structure for collinear acceleration.
slides icon Slides MOZBB2 [8.339 MB]  
Conceptual Design of a Compact 500 MeV Short-Pulse Two-Beam Acceleration Demonstrator at Argonne Wakefield Accelerator  
MOPLH27   use link to see paper's listing under its alternate paper code  
  • J.H. Shao, M.E. Conde, D.S. Doran, G. Ha, J.G. Power
    ANL, Lemont, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  Short-pulse two-beam acceleration (SP-TBA) is an advanced acceleration concept that can potentially meet the luminosity and cost requirements in future linear colliders and XFELs. In this concept, a high charge drive beam travelling through a structure excites short wakefield field (<20 ns) which is used to accelerate a low charge main beam in a parallel structure. A SP-TBA program is under development at the Argonne Wakefield Accelerator (AWA) facility where 300 MW generated power, 150 MeV/m acceleration gradient, and simplified staging have been successfully achieved. Based on the ongoing effort of novel dielectric disk structure, fast kicker/septum, and improved beam quality, a fully-functional demonstrator that can fit into AWA’s current bunker is proposed to demonstrate key technologies required by SP-TBA based machines: GW power generation, >250 MV/m acceleration, drive beam distribution/transportation, successive main beam acceleration, etc. The 70 MeV drive beam will be decelerated by four power extractors in two stages so as to boost the main beam energy from 15 MeV to 500 MeV by the four corresponding accelerators. The conceptual design will be presented in detail.  
slides icon Slides MOZBB3 [6.859 MB]  
High Brightness CW Electron Beams From Superconducting RF Photoinjector  
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • T. Hayes, Y.C. Jing, V. Litvinenko, J. Ma, G. Narayan, I. Pinayev, F. Severino, K.S. Smith, G. Wang
    BNL, Upton, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • K. Shih
    SBU, Stony Brook, New York, USA
  The next generation electron beam facilities, such as high-power free electron lasers (FELs), energy-recovery linacs, or coolers for hadron beams, raise the strict requirements on the quality of the electron beam. Fortunately, the superconducting RF (SRF) technology is well suited for generating CW electron beams in high accelerating gradient environments. Recent achievements in the SRF photoinjector realm demonstrated the ability of the modern SRF guns to provide stable operation with high-brightness beams. In this paper, we report the excellent performance of our SRF gun with CsK2Sb photocathode that was built for the Coherent electron Cooling (CeC) Proof of Principle (PoP) experiment at RHIC. The gun is generating high charge electron bunches (up to 10 nC per bunch) and low transverse emittances with the cathodes operating for months without significant loss of quantum efficiency. We will provide a brief overview of the main stages of the commissioning of our gun along with a detailed discussion of the main challenges during the operation. This is followed by the description of the emittance studies, including our experimental results and numerical simulations.  
slides icon Slides MOZBB4 [10.524 MB]  
MOZBB5 Magnetized Electron Source for JLEIC Cooler -1
WEPLO22   use link to see paper's listing under its alternate paper code  
  • R. Suleiman, P.A. Adderley, J.F. Benesch, D.B. Bullard, J.M. Grames, J. Guo, F.E. Hannon, J. Hansknecht, C. Hernandez-Garcia, R. Kazimi, G.A. Krafft, M.A. Mamun, M. Poelker, M.G. Tiefenback, Y.W. Wang, S. Zhang
    JLab, Newport News, Virginia, USA
  • J.R. Delayen, G.A. Krafft, S.A.K. Wijethunga, J.T. Yoskowitz
    ODU, Norfolk, Virginia, USA
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and supported by Laboratory Directed Research and Development funding.
Magnetized bunched-beam electron cooling is a critical part of the Jefferson Lab Electron Ion Collider (JLEIC). Strong cooling of ion beams will be accomplished inside a cooling solenoid where the ions co-propagate with an electron beam generated from a source immersed in magnetic field. This contribution describes the production and characterization of magnetized electron beam using a compact 300 kV DC high voltage photogun and bialkali-antimonide photocathodes. Beam magnetization was studied using a diagnostic beamline that includes viewer screens for measuring the shearing angle of the electron beamlet passing through a narrow upstream slit. Correlated beam emittance with magnetic field at the photocathode was measured for various laser spot sizes. Measurements of photocathode lifetime were carried out at different magnetized electron beam currents up to 28 mA and high bunch charge up to 0.7 nano-Coulomb was demonstrated.
slides icon Slides MOZBB5 [6.626 MB]  
poster icon Poster MOZBB5 [1.549 MB]  
MOZBB6 Measuring the Mean Transverse Energy of Pump-Probe Photoemitted Electrons -1
MOPLH21   use link to see paper's listing under its alternate paper code  
SUPLE11   use link to see paper's listing under its alternate paper code  
  • C.M. Pierce, I.V. Bazarov, L. Cultrera, J.M. Maxson
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams.
Low effective mass semiconductor photocathodes have historically failed to exhibit the sub-thermal mean transverse energies (MTEs) expected of them based on their band structure. However, conservation of transverse momentum across the vacuum interface, and therefore a low MTE in these materials, has been observed in time resolved ARPES*. To help bridge this gap, we measured the MTE of the pump probe photoemitted electrons seen in the ARPES experiment using methods typical of accelerator physics. We compare the results of these measurements with those of both communities and discuss them in the context of photoemission physics.
* Kanasaki, J., Tanimura, H., & Tanimura, K. (2014). Imaging Energy-, Momentum-, and Time-Resolved Distributions of Photoinjected Hot Electrons in GaAs. Physical Review Letters, 113(23), 237401.
slides icon Slides MOZBB6 [6.384 MB]