MOPLO —  Monday Poster Session-Lake Ontario   (02-Sep-19   16:30—18:00)
Paper Title Page
MOPLO01 A Beam Spreader System for LCLS-II -1
  • T.G. Beukers, J.W. Amann, Y.M. Nosochkov
    SLAC, Menlo Park, California, USA
  For the LCLS-II project, the SLAC National Accelerator Laboratory is installing a new superconducting RF linac capable of continuously delivering 4 GeV electron bunches spaced 1.1 microseconds apart. A spreader system is required to distribute the beam between a soft X-ray or hard X-ray undulator, and a beam dump. An additional beam diverter is required in the front end of the linac to divert 100 MeV electrons to a diagnostic line. Both the spreader and diagnostic diversion systems are designed to operate on a bunch by bunch basis via the combination of fast kickers and a Lambertson septum. This paper presents a summary of the optics, kicker, and septum design. Of specific interest is the unique challenge associated with building a high repetition, high stability, spreader capable of diverting a single bunch without disturbing neighboring bunches. Additional discussion includes the application of the spreader technology to the proposed DASEL/S30XL beamline. This beamline will acceptμbunches evenly spaced between the undulator bound bunches, thus requiring a kicker with the same repetition rate as LCLS-II but a pulse width extended to approximately 600 ns.  
poster icon Poster MOPLO01 [1.281 MB]  
Status of the Low Energy Electron Beam System Measuring the Liquid Lithium Film Thickness at FRIB  
  • J. Gao, Y. Hao, T. Kanemura, F. Marti
    FRIB, East Lansing, Michigan, USA
  Funding: This work is supported by U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
Developing a stable and uniform thin liquid lithium film (around 10 µm) is critical for high intensity heavy ion beam charge stripping at Facility for Rare Isotope Beams (FRIB). Due to the thickness dependent scattering effect of electrons by the film, the low energy electron beam (LEEB) technique can be used to provide a fast response film thickness diagnostic both in time and space domain [1]. By implementing a 30 kV electron beam, we developed a LEEB testing system at FRIB. We report the offline testing results of the electron transmission through the carbon foils with known thickness. Comparing the experimental results and CASINO simulations [2], quantitative information about the film thickness has been obtained. Preliminary results on the high velocity, thin liquid lithium film thickness measurement are discussed.
[1] I. Gomes, et al., Nucl. Phys. A 746, 453-456 (2004).
[2] D. Drouin, et al., Scanning vol. 29, 92-101 (2007).
MOPLO03 Final Conversion of the Spallation Neutron Source Extraction Kicker Pulse Forming Network to a High Voltage Solid-State Switch -1
  • B. Morris, R.B. Saethre
    ORNL RAD, Oak Ridge, Tennessee, USA
  Funding: UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy
The Spallation Neutron Source (SNS) extraction kicker 60Hz pulsed system uses 14 Blumlein pulse-forming network (PFN) modulators that require timing synchronization with stable rise times. A replacement design has been investigated and the kickers have been converted over to use a solid-state switch design, eliminating the lifetime and stability issues associated with thyratrons and subsequent maintenance costs. All kickers have been converted, preventing thyratron jitter from impacting the beam performance and allowing higher-precision target impact. This paper discusses the completion of the conversion of the high-voltage switch from a thyratron to a solid-state switch with improved stability of the extraction system and associated accelerator beam stability.
poster icon Poster MOPLO03 [1.071 MB]  
MOPLO04 Progress in Time-Resolved MeV Transmission Electron Microscopy at UCLA -1
SUPLM13   use link to see paper's listing under its alternate paper code  
  • P.E. Denham
    UCLA, Los Angeles, USA
  We describe here two new enhancements developed for the time-resolved microscope at the UCLA PEGASUS Lab based on the use of a radiofrequency photoinjector as an ultrafast electron source and permanent magnet quadrupoles as electron lenses. The first enhancement is a flexible optical column design including hybrid-style stronger focusing quadrupoles, yielding a 60% magnification increase, and a collimator to improve imaging contrast. This new optical system will have the ability to switch between real-space imaging and diffraction pattern imaging with variable magnification. The second enhancement is a high-frequency (X-band) cavity downstream from the (S-band) photoinjector to reduce the beam energy spread. These enhancements are crucial for improving contrast and image quality. In addition, a pulse-wire alignment method to fiducialize the quadrupole positions to better than 20-um precision is used to reduce the aberrations induced by misalignment and achieve spatial resolution at the 20 nm-level.  
MOPLO06 Black Gun Technologies for DC Photoinjectors -1
  • E.J. Montgomery, C. Jing, S. Poddar
    Euclid Beamlabs LLC, Bolingbrook, USA
  • J.E. Butler
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • S. Zhang
    JLab, Newport News, Virginia, USA
  Funding: Work supported by the US DOE Office of Science, Office of Nuclear Physics, grant number DESC0019688. Work at Argonne CNM under Contract No. DE-AC02-06CH11357.
Euclid Beamlabs is developing a new "Black Gun" concept in direct current (DC) photoinjectors. To reduce electron-stimulated desorption indirectly influenced by stray photoemission, we are testing advanced optical coatings and low-scattering optics compatible with the extreme high vacuum (XHV) environment of modern DC photoinjectors. Stray light in DC photoinjectors (in proportion to the photoemitted charge) causes off-nominal photoemission, initiating electron trajectories which intercept downstream surfaces. This causes electron-stimulated desorption of atoms, which ionize and may back-bombard the cathode, reducing its charge lifetime. Back-bombardment is key for high average current or high repetition rate. First, we report on progress developing optical skimmers based on Butler baffles to collimate both incoming and outgoing laser beams. Second, we describe candidate coatings for reduction of scattered light. Requirements for these coatings are that they be conducting, optically black at the drive laser wavelength, conformally applied to complex geometry, and XHV-compatible with negligible outgassing.
MEMS Based Multibeam Ion Linacs  
  • T. Schenkel, Q. Ji, A. Persaud, P.A. Seidl
    LBNL, Berkeley, California, USA
  • K. Afridi, A. Lal, D. Ni
    Cornell University, Ithaca, New York, USA
  Funding: Work at LBNL was conducted under the auspices of the US DOE (DE-AC0205CH11231) and supported by ArpaE. Device fab at the Cornell Nano Fab facility was supported by NSF (Grant 384 No.ECCS-1542081).
We report on the development of multi-beam RF linear ion accelerators that are formed from stacks o low cost wafers. Wafers are prepared using MEMS techniques. We have demonstrated acceleration of ions in a 3x3 beamlet array with ion currents in the 0.1 mA range and acceleration at the 10 keV in lattice of RF (13 MHz) acceleration units and electrostatic quadrupoles. We will describe the status and plans for scaling to 10x10 beams, ion currents >1 mA and ion energies >100 keV in a compact, low cost setup for applications in materials processing.
[1] P. A. Seidl, et al., Rev. Sci. Instr. 89, 053302 (2018); doi: 10.1063/1.5023415
Design and Commissioning of the FRIB Linac Room Temperature Magnets  
  • Q. Zhao
    NSCL, East Lansing, Michigan, USA
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University
FRIB driver linac is a cw heavy ion superconducting machine with beam power up to 400 kW. It has unique double-folded layout, and a 70-degree bending systems to deliver beam on target. Room temperature magnets (dipoles, quadrupoles, sextupoles, and steerers) are used in the warm areas. Value engineering had been performed in the magnet designs in order to obtain good field uniformity while keeping low cost of power supplies and easy manufacture. Each type of magnets was also optimized into several families based on field strength and aperture requirement. After fabrication, the field of each magnet was either measured with rotating coils or mapped with an Hall probe. We will also present the commissioning results with beams in the first folding area.
MOPLO09 A Pulsed, Current Regulated Magnet Power Supply for Small Magnets -1
SUPLS03   use link to see paper's listing under its alternate paper code  
  • G.D. Wyche, B.L. Beaudoin, L. Dovlatyan, D.F. Sutter
    UMD, College Park, Maryland, USA
  Funding: Work supported by U. S. Department of Energy grant number DESC00010301
The University of Maryland Electron Ring (UMER) has two pulsed quadrupoles in the injection section that must be current regulated to the same precision as the other DC quadrupoles in the ring, as well as accurately synchro-nized to the ring operating cycle. To meet this need, a practical pulsed current, regulated power supply has been designed and built using a commercial power operational amplifier for output, standard operational amplifiers for feedback control and monitoring, and matched resistor pairs to produce the desired transfer function of 10 Volts to 6 Amperes. For other applications the circuit can be modified to produce a range of transfer functions by varying the appropriate resistor pair ratios. Output pulse width and timing are generated by a standardized TTL pulse from the control system that gates the output of the amplifier. Installed safety circuitry detects the absence of a proper control pulse, an open circuit or shorted output, and measures and returns to the control system the actual operating amplitude of the current pulse. In this paper we present the design, implementation, and operational results of the prototyped pulsed current source.
MOPLO12 The RF BPM Pickup Electrodes Development for the APS-MBA Upgrade -1
  • X. Sun, R.M. Lill
    ANL, Lemont, Illinois, USA
  Beam stability is critical for the Advanced Photon Source (APS) multi-bend achromat (MBA) lattice up-grade and will employ 560 radio frequency (RF) beam position monitors (BPMs). The RF BPMs will provide the primary measurement of the electron beam. Design goals for the BPM assembly include high sensitivity, low wakefield impedance, and ultra-mechanically stability. The design, electromagnetic simulation, manufacturing tolerance and prototype testing will be presented in this paper.
*Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
MOPLO13 Field Quality Analysis of Interaction Region Quadrupoles for JLEIC -1
  • G.L. Sabbi
    LBNL, Berkeley, California, USA
  • B.R. Gamage, T.J. Michalskipresenter, V.S. Morozov, R. Rajput-Ghoshal, M. Wiseman
    JLab, Newport News, Virginia, USA
  • Y.M. Nosochkov, M.K. Sullivan
    SLAC, Menlo Park, California, USA
  Funding: Work supported by the US Department of Energy Office of Science.
The JLEIC physics goals of high luminosity and a full acceptance detector result in significant design challenges for the Interaction Region quadrupoles. Key requirements include large aperture, high field, compact transverse and longitudinal dimensions, and tight control of the field errors. In this paper, we present and discuss field quality estimates for the IR Quadrupoles of both electron and ion beamlines, obtained by integrating experience from pre-vious projects with realistic designs consistent with the specific requirements of the JLEIC collider.
poster icon Poster MOPLO13 [0.842 MB]  
MOPLO14 From Start to Finish: Using 3D Printing Techniques to Build CBETA -1
  • G.J. Mahler, S.J. Brooks, S.M. Trabocchi
    BNL, Upton, New York, USA
  Funding: NYSERDA contract with BNL
The extensive use of a simple 3D printer allowed for fast prototyping and development of many components used to build CBETA.
MOPLO15 Engineering and Fabrication of the High Gradient Structure for Compact Ion Therapy Linac -1
  • O. Chimalpopoca, R.B. Agustsson, S.V. Kutsaev, A.Yu. Smirnov, A. Verma
    RadiaBeam, Santa Monica, California, USA
  • A. Barcikowski, R.L. Fischer, B. Mustapha
    ANL, Lemont, Illinois, USA
  RadiaBeam is fabricating a novel ultra-high gradient linear accelerator for the Advanced Compact Carbon Ion LINAC (ACCIL) project. The ACCIL is an Argonne National Laboratory (ANL) led project, in collaboration with RadiaBeam, designed to be capable of delivering sufficiently energized carbon ions and protons while maintaining a 50 m footprint. This is made possible by the development of S-Band 50 MV/m accelerating structures for particles with beta of 0.3 or higher. Such high gradient accelerating structures require particular care in their engineering details and fabrication process to limit the RF breakdown at the operating gradients. The details of fabrication and engineering design of the accelerating structure will be presented.  
poster icon Poster MOPLO15 [1.060 MB]  
Large-Scale Dewar Testing of FRIB Production Cavities: Statistical Analysis  
MOYBB4   use link to access more material from this paper's primary paper code  
  • C. Zhang, W. Chang, W. Hartung, S.H. Kim, J.T. Popielarski, K. Saito, J.F. Schwartz, T. Xu
    FRIB, East Lansing, Michigan, USA
  The Facility for Rare Isotope Beams (FRIB) requires a driver linac with 324 superconducting cavities to deliver ion beams at 200 MeV per nucleon. About 1/3 of the cavities are quarter-wave resonators (QWRs, 805. MHz); the rest are half-wave resonators (HWRs, 322 MHz). FRIB cavity production is nearly complete, with more than 90% of the required cavities certified for installation into cryomodules (as of May 2019). We have accumulated a large data set on performance of production QWRs and HWRs during Dewar certificating testing of jacketed cavities. In this paper, we will report on the data analysis, including statistics on the BCS resistance, residual resistance, energy gap, and Q-slope. Additionally, we will discuss performance limitations and conditioning (multipacting, field emission).  
slides icon Slides MOPLO16 [1.185 MB]  
Large-Scale Dewar Testing of FRIB Production Cavities: Results  
  • W. Hartung, W. Chang, S.H. Kim, D. Norton, J.T. Popielarski, K. Saito, J.F. Schwartz, T. Xu, C. Zhang
    FRIB, East Lansing, Michigan, USA
  The Facility for Rare Isotope Beams (FRIB), under construction at Michigan State University (MSU), includes a superconducting driver linac to deliver ion beams at 200 MeV per nucleon. The driver linac requires 104 quarter-wave resonators (QWRs, β = 0.041 and 0.085) and 220 half-wave resonators (HWRs, β = 0.29 and 0.54). The jacketed resonators are Dewar tested at MSU before installation into cryomodules. The cryomodules for β = 0.041, 0.085, and 0.29 have been completed and certified; 89% of the β = 0.54 HWRs have been certified (as of May 2019). The Dewar certification tests have provided valuable information on the performance of production QWRs and HWRs at 4.3 K and 2 K and on performance limits. Results will be presented.  
MOPLO18 Thermal Analysis of the LANSCE H+ RFQ Test Stand Faraday Cup -1
  • E.N. Pulliam, I. Draganić, J.L. Medina, J.P. Montross, J.F. O’Hara, L. Rybarcyk
    LANL, Los Alamos, New Mexico, USA
  The Los Alamos Neutron Science Center (LANSCE) op-erates one of the nation’s most powerful linear accelera-tors (LINAC). Currently the facility utilizes two 750 keV Cockcroft-Walton (CW) based injectors for transporting H+ and H beams into the 800 MeV accelerator. A Radio Frequency Quadrupole (RFQ) design is being proposed to replace the aged CW injectors. An important component of the RFQ Test Stand is the Faraday cup that is assem-bled at the end of the Low Energy Beam Transport (Phase 1 LEBT) and Medium Energy Beam Transport (Phase 3 MEBT). The Faraday cup functions simultaneously as both a beam diagnostic and as a beam stop for each of the three project phases. This paper describes various aspects of the design and analysis of the Faraday cup. The first analysis examined the press fit assembly of the graphite cone and the copper cup components. A finite element analysis (FEA) evaluated the thermal expansion proper-ties of the copper component, and the resulting material stress from the assembly. Second, the beam deposition and heat transfer capability were analyzed for LEBT and MEBT beam power levels. Details of the calculations and analysis will be presented.  
poster icon Poster MOPLO18 [3.390 MB]  
MOPLO19 Test Results of PIP2IT MEBT Vacuum Protection System -1
  • A.Z. Chen, R. Andrews, C.M. Baffes, D.D. Lambert, L.R. Prost, A.V. Shemyakin, T.J. Zuchnik
    Fermilab, Batavia, Illinois, USA
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics
The central part of PIP-II program of upgrades proposed for the Fermilab injection complex is an 800 MeV, 2 mA, CW-compatible SRF linac. Acceleration in superconducting cavities begins from a low energy of 2.1 MeV, so that the first cryomodule, Half Wave Resonator (HWR) borders the warm Medium Beam Transport (MEBT) line. To minimize the amount of gas that may enter the SRF linac in a case if a vacuum failure occurs in the warm front end, a vacuum protection system is envisioned to be used in the PIP-II MEBT. It features a fast closing valve with two sensors and a differential pumping insert. The system prototype is installed in the PIP-II Injector Test (PIP2IT) accelerator and recently is successfully tested in several modes modelling the vacuum failures. The report presents the design of the vacuum protection system and results of its tests.
MOPLO20 Quench Performance and Field Quality of the 15 T Nb3Sn Dipole Demonstrator MDPCT1 in the First Test Run -1
  • A.V. Zlobin, E.Z. Barzi, J.R. Carmichael, G. Chlachidze, J. DiMarco, V.V. Kashikhin, S. Krave, I. Novitski, C.R. Orozco, S. Stoynev, T. Strauss, M.A. Tartaglia, D. Turrioni
    Fermilab, Batavia, Illinois, USA
  Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
U.S. Magnet Development Program (US-MDP) is developing high-field accelerator magnets for a post-LHC hadron collider. In June 2019 Fermilab has tested a new Nb3Sn dipole model, which produced a world record field of 14.1 T at 4.5 K. The magnet design is based on 60 mm aperture 4-layer shell-type coils, graded between the inner and outer layers. The Rutherford cable in the two innermost layers consists of 28 strands 1.0 mm in diameter and the cable in the two outermost layers 40 strands 0.7 mm in diameter. Both cables were fabricated at Fermilab using RRP Nb3Sn composite wires produced by Bruker-OST. An innovative mechanical structure based on aluminum clamps and a thick stainless-steel skin was developed to preload brittle Nb3Sn coils and support large Lorentz forces. The maximum field for this design is limited by 15 T due to mechanical considerations. The first magnet assembly was done with lower coil pre-load to achieve 14 T and minimize the risk of coil damage during assembly. The 15 T dipole demonstrator design and the first results of magnet cold tests including quench performance and magnetic measurements are presented.
Multipacting Simulations: Field Strength Measurements in a Coaxial Waveguide  
  • D.M. Cheatham, J.R. Cary, J.B. Leddy, D. Mainpresenter, D.N. Smithe, P. Stoltz, S.A. Veitzer
    Tech-X, Boulder, Colorado, USA
  We present a study of multipactor in a coaxial waveguide. Multipaction is a commonly encountered problem RF engineers face, that causes significant damage to RF structures, in which there are very often no analytical solutions. Therefore, often the only way to predict multipacting is by using numerical solvers. For this study, the analysis was performed using simulated data obtained with the FDTD PIC code VSim. The first simulation, in which the initial primary electrons were loaded uniformly inside a coax, successfully showed the multipacting effect. A second simulation shows how results can be generated much faster using primary electrons that are field-scaled. This a feature in VSim that allows for multiple RF field strengths to simultaneously exist in one simulation. As a result, the optimal conditions for the coax to multipact were measured, allowing for accurate multipacting predictions. This method is highly efficient and ideal for RF design optimization.  
MOPLO23 Investigation of Various Fabrication Methods to Produce a 180GHz Corrugated Waveguide Structure in 2mm Diameter ­0.5m ­Long Copper Tube for the Compact Wakefield Accelerator for FEL Facility -1
  • K.J. Suthar, D.S. Doran, W.G. Jansma, S.S. Sorsher, E. Trakhtenberg, G.J. Waldschmidt, A. Zholents
    ANL, Lemont, Illinois, USA
  • A.E. Siy
    UW-Madison/PD, Madison, Wisconsin, USA
  Funding: This research used resources of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated by the Argonne National Laboratory under Contract No. DE­AC02­06CH11357.
Argonne National Laboratory is developing a 180 GHz wakefield structure that will house in a co-linear array of accelerators to produce free-electron laser-based X-rays. The proposed corrugated waveguide structure will be fabricated on the internal wall of 0.5m long and 2mm nominal diameter copper tube. The estimated dimensions of these parallel corrugations are 200 µm in pitch with 100 µm side length (height and width). The length scale of the structure and requirements of the magnetic field-driven dimensional tolerances have made the structure challenging to produce. We have employed several method such as optical lithography, electroforming, electron discharge machining, laser ablation, and stamping to produce the initial structure from a sheet form. The successive fabrication steps, such as bending, brazing, and welding, were performed to achieve the long tubular-structure. This paper discusses various fabrication techniques, characterization, and associated technical challenges in detail.
[1] A. Zholents et al., Proc. 9-th Intern. Part. Acc. Conf., IPAC2018, Vancouver, BC, Canada, p. 1266, (2018)
MOPLO24 A Novel Technique for Pulsed Operation of Magnetrons without Modulation of Cathode Voltage -1
  • G.M. Kazakevich, R.P. Johnsonpresenter
    Muons, Inc, Illinois, USA
  • T.N. Khabiboulline, V.A. Lebedev, G.V. Romanov, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  Modern pulsed superconducting accelerators of megawatt beams require efficient RF sources controllable in phase and power. For each Superconducting RF (SRF) cavity is desirable a separate RF source with power up to hundreds of kW with pulse duration in the millisecond range. The efficiency of the traditional RF sources (klystrons, IOTs, solid-state amplifiers) is lower than that of the magnetrons, while the cost of a unit of RF power is much higher. Therefore the magnetron-based RF sources would significantly reduce the capital and operation costs in comparison with the traditional RF sources. A recently developed an innovative technique makes possible the pulsed generation of magnetrons powered below the self-excitation threshold voltage. This technique does not require pulse modulators to form RF pulses. The magnetron operation in this regime is stable, low noise, controllable in phase and power, and provides higher efficiency than other types of RF power sources. It allows operation in pulsed modes with large duty factor. The developed technique and its experimental verification are considered and discussed.