07: Accelerator Technology
Paper Title Page
MOYBB1
Recent Advance in SRF Cavity Technologies  
 
  • M. Martinello
    Fermilab, Batavia, Illinois, USA
 
  FNAL has been making great accomplishments in SRF technology recent years under her leadership. Notably the nitrogen doping technique to significantly increase the quality factor of SRF cavities has been made use of all over the world nowadays, being exemplified by LCLS II. In addition, the theoretical understanding of the effect is progressing well. Systematic, extensive study/analysis is ongoing on the basis of the joint effort of experiment and theory. Deeper understanding of RF superconductivity obtained through these efforts is benefitting world-wide accelerator institutes using SRF technology.  
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MOYBB2 Recent Advance in ECR Ion Sources 31
 
  • G. Machicoane, N.K. Bultman, P. Morrison, M. Omelayenko, X. Rao
    FRIB, East Lansing, Michigan, USA
  • D. Arbelaez, R.R. Hafalia, P. Pan, S. Prestemon
    LBNL, Berkeley, California, 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.
High continuous wave (cw) current of highly charged ion beams are required for several heavy ion accelerator facilities including the Facility for Rare Isotope Beams (FRIB). In most cases, Electron-Cyclotron-Resonance (ECR) ion sources remain the only ion source capable to meet the beam intensity requirement for these facilities. Performances of ECR ion source have increased by several order of magnitude since their inception in the 1970s mostly driven by increasing the resonance frequency with today current state of the art ECR ion source operating from 24 to 28 GHz. This paper provides an overview of recent advance in the design and operation of ECR ion source including plans to develop the next generation of ion source capable of operating above 40 GHz. A detailed account of the design and status of the new superconducting ECR ion source in construction for FRIB will also be reported.
 
slides icon Slides MOYBB2 [9.483 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOYBB2  
About • paper received ※ 02 September 2019       paper accepted ※ 16 November 2020       issue date ※ 08 October 2019  
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MOYBB3 Progress in Nb3Sn SRF Cavities at Cornell University 37
SUPLS08   use link to see paper's listing under its alternate paper code  
 
  • R.D. Porter, H. Hu, M. Liepe, N.A. Stilin, Z. Sun, M.J. Tao
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Niobium-3 Tin (NbSn) is the most promising alternative material for next-generation SRF cavities. The material can obtain high quality factors (> 1010) at 4.2 K and could theoretically support ~ 96 MV/m operation of a TESLA elliptical style cavity. Current Nb3Sn cavities made at Cornell University achieve high quality factors but are limited to about 17 MV/m in CW operation due to the presence of a surface defect. Here we examine recent results on studying the quench mechanism and propose that surface roughness is a major limiter for accelerating gradients. Furthermore, we discuss recent work on reducing the surface roughness including chemical polishing, modification of material growth, and tin electroplating.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOYBB3  
About • paper received ※ 02 September 2019       paper accepted ※ 12 September 2019       issue date ※ 08 October 2019  
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MOYBB4 Large-Scale Dewar Testing of FRIB Production Cavities: Statistical Analysis 41
MOPLO16   use link to see paper's listing under its alternate 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 MOYBB4 [1.200 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOYBB4  
About • paper received ※ 01 September 2019       paper accepted ※ 19 November 2019       issue date ※ 08 October 2019  
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MOYBB6 X-Ray Detector Array for Spatial and Temporal Diagnostic at the LANSCE Linac 47
 
  • M. Sanchez Barrueta, G.O. Bolme, J.T.M. Lyles, J.E. Zane
    LANL, Los Alamos, New Mexico, USA
  • R.Z. Pinsky
    NERS-UM, Ann Arbor, Michigan, USA
 
  Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract 89233218CNA000001
A recent industrial development has made possible the use of chip-scale radiation detectors by combining a Cerium-doped Lutetium based scintillator crystal optically coupled with a Silicon Photomultiplier (SiPM) as a detector. At the Los Alamos Neutron Science Center (LANSCE), there has been an ongoing effort to determine the location of high voltage breakdowns of the accelerating radio-frequency field inside of an evacuated resonant cavity. Tests were conducted with an array of 8 X-ray detectors with each detector observing a cell of the Drift Tube Linac (DTL) cavity. The array can be moved along the DTL cavity and record X-ray emissions from a section of the cavity and their timing with respect to the RF field quench using a fast 8 channel mixed-signal oscilloscope. This new diagnostic allowed us to map the most energetic emissions along the cavity and reduce the area to investigate. A thorough visual inspection revealed that one of the ion pump grating welds in the suspected area was exposing a small gap and melting copper on both sides. Sparking across this discontinuity is believed to be a source of electrons that drive the high voltage breakdowns in the drift tube cells.
 
slides icon Slides MOYBB6 [39.283 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOYBB6  
About • paper received ※ 28 August 2019       paper accepted ※ 12 September 2019       issue date ※ 08 October 2019  
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MOPLO01 A Beam Spreader System for LCLS-II 236
 
  • 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 [1.256 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO01  
About • paper received ※ 27 August 2019       paper accepted ※ 31 August 2019       issue date ※ 08 October 2019  
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MOPLO03 Final Conversion of the Spallation Neutron Source Extraction Kicker Pulse Forming Network to a High Voltage Solid-State Switch 240
 
  • 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 [1.073 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO03  
About • paper received ※ 23 August 2019       paper accepted ※ 19 November 2019       issue date ※ 08 October 2019  
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MOPLO04 Progress in Time-Resolved MeV Transmission Electron Microscopy at UCLA 243
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.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO04  
About • paper received ※ 28 August 2019       paper accepted ※ 04 September 2019       issue date ※ 08 October 2019  
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MOPLO06 Black Gun Technologies for DC Photoinjectors 247
 
  • 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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO06  
About • paper received ※ 04 September 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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MOPLO07 MEMS Based Multibeam Ion Linacs 249
 
  • T. Schenkel, G. Giesbrecht, Q. Ji, A. Persaud, P.A. Seidl
    LBNL, Berkeley, California, USA
  • K. Afridi, A. Lal, D. Ni, S. Sinha
    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
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO07  
About • paper received ※ 27 August 2019       paper accepted ※ 16 November 2020       issue date ※ 08 October 2019  
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MOPLO09 A Pulsed, Current Regulated Magnet Power Supply for Small Magnets 252
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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO09  
About • paper received ※ 28 August 2019       paper accepted ※ 04 September 2019       issue date ※ 08 October 2019  
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MOPLO12 The RF BPM Pickup Electrodes Development for the APS-MBA Upgrade 256
 
  • 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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO12  
About • paper received ※ 27 August 2019       paper accepted ※ 31 August 2019       issue date ※ 08 October 2019  
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MOPLO13 Field Quality Analysis of Interaction Region Quadrupoles for JLEIC 259
 
  • G.L. Sabbi
    LBNL, Berkeley, California, USA
  • B.R. Gamage, T.J. Michalski, 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 [0.847 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO13  
About • paper received ※ 27 August 2019       paper accepted ※ 06 September 2019       issue date ※ 08 October 2019  
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MOPLO14 From Start to Finish: Using 3D Printing Techniques to Build CBETA 263
 
  • 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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO14  
About • paper received ※ 14 August 2019       paper accepted ※ 31 August 2019       issue date ※ 08 October 2019  
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MOPLO15 Engineering and Fabrication of the High Gradient Structure for Compact Ion Therapy Linac 267
 
  • 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 [1.050 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO15  
About • paper received ※ 28 August 2019       paper accepted ※ 12 September 2019       issue date ※ 08 October 2019  
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MOPLO17 Large-Scale Dewar Testing of FRIB Production Cavities: Results 270
 
  • 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.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO17  
About • paper received ※ 08 November 2019       paper accepted ※ 26 November 2019       issue date ※ 08 October 2019  
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MOPLO18 Thermal Analysis of the LANSCE H+ RFQ Test Stand Faraday Cup 274
 
  • 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 [3.399 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO18  
About • paper received ※ 27 August 2019       paper accepted ※ 25 November 2019       issue date ※ 08 October 2019  
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MOPLO19 Test Results of PIP2IT MEBT Vacuum Protection System 278
 
  • 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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO19  
About • paper received ※ 28 August 2019       paper accepted ※ 03 September 2019       issue date ※ 08 October 2019  
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MOPLO20 Quench Performance and Field Quality of the 15 T Nb3Sn Dipole Demonstrator MDPCT1 in the First Test Run 282
 
  • 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.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO20  
About • paper received ※ 27 August 2019       paper accepted ※ 03 September 2019       issue date ※ 08 October 2019  
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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 286
 
  • 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)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO23  
About • paper received ※ 27 August 2019       paper accepted ※ 06 September 2019       issue date ※ 08 October 2019  
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MOPLO24 A Novel Technique for Pulsed Operation of Magnetrons without Modulation of Cathode Voltage 290
 
  • G.M. Kazakevich, R.P. Johnson
    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.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO24  
About • paper received ※ 29 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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WEZBA1
Status and Future Directions for High Power Neutron Production Targets  
 
  • C.N. Barbier
    ORNL, Oak Ridge, Tennessee, USA
 
  Development of megawatt class targets for neutron production remains one of the largest engineering challenges in the field of accelerator science. This talk will review state of the art in neutron target capabilities and ongoing R&D of next generation targets.  
slides icon Slides WEZBA1 [18.736 MB]  
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WEZBA2 Experience and Lessons in FRIB Superconducting Quarter-Wave Resonator Commissioning 646
 
  • S.H. Kim, H. Ao, F. Casagrande, W. Chang, C. Compton, A. Facco, V. Ganni, E. Gutierrez, W. Hartung, N. Hasan, P. Knudsen, T.L. Larter, H. Maniar, S.J. Miller, D.G. Morris, P.N. Ostroumov, A.S. Plastun, J.T. Popielarski, L. Popielarski, H.T. Ren, K. Saito, M. Thrush, D.R. Victory, J. Wei, M. Xu, T. Xu, Y. Yamazaki, C. Zhang, S. Zhao
    FRIB, East Lansing, Michigan, USA
 
  The superconducting (SC) linear accelerator (linac) for the Facility for Rare Isotope Beams (FRIB) has one quarter-wave resonator (QWR) segment and two half-wave resonator (HWR) segments. The first linac segment (LS1) contains twelve β = 0.041 and ninety-two β = 0.085 QWRs operating at 80.5 MHz, and thirty-nine SC solenoids. Superconducting radiofrequency (SRF) commissioning and beam commissioning of LS1 was completed in April 2019. The design accelerating gradients (5.1 MV/m for β = 0.041 and 5.6 MV/m for β = 0.085) were achieved in all cavities with no multipacting or field emission issues. The cavity field met the design goals: peak-to-peak stability of ±1% in amplitude and ±1° in phase. We achieved 20.3 MeV/u ion beams of Ar, Kr, Ne, and Xe with LS1. In this paper, we will discuss lessons learned from the SRF commissioning of the cryomodules and methods developed for efficient testing, conditioning, and commissioning of more than 100 SC cavities, each with its own independent RF system.  
slides icon Slides WEZBA2 [2.841 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEZBA2  
About • paper received ※ 03 September 2019       paper accepted ※ 05 December 2019       issue date ※ 08 October 2019  
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WEZBA3 No Beam-Loss Quadrupole Scan for Transverse Phase Space Measurements 650
 
  • K. Fukushima, T. Maruta, P.N. Ostroumov, T. Yoshimoto
    FRIB, 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.
Facility for Rare Isotope Beams (FRIB) at Michigan State University is based on a high power heavy ion linac and beam commissioning is under way. For evaluation of beam Twiss parameters and rms emittance, we routinely use multiple profile measurements while the strength of an upstream quadrupole is varied. The change of the quadrupole strength results in a beam mismatch downstream of the profile monitor which can cause beam losses. This is not acceptable in a high energy beamline. To avoid this transverse mismatch, we developed a beam matching procedure by optimization of quadrupoles’ setting downstream of the profile monitor. Using this procedure we were able to eliminate beam losses during the quadrupole scan, and evaluate beam Twiss parameters and rms emittance. Examples of using this procedure in the folding segment of the FRIB linac will be reported.
 
slides icon Slides WEZBA3 [7.964 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEZBA3  
About • paper received ※ 27 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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WEZBA4
Characterization and Analysis of Nanocrystalline Diamond as Stripper Foils  
 
  • L.V. Saturday, P.D. Rack
    University of Tennessee, Knoxville, USA
  • D.P. Briggs, P.D. Rack, S.T. Retterer
    CNMS, Oak Ridge, USA
  • N.J. Evans, C.F. Luck
    ORNL RAD, Oak Ridge, Tennessee, USA
  • L.L. Wilson
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.
The 1.4 MW Spallation Neutron Source (SNS) uses nanocrystalline diamond (NCD) foils to strip 1 GeV H ions to protons during injection into the accumulator ring. The SNS Proton Power Upgrade will double the power deposited into the NCD foils by increasing the beam current by 50% and linac energy by 30%. This makes understanding the failure modes of the NCD foils increasingly important. In this work we report on experiments using a 30 keV, 5 mA electron gun capable of simulating SNS PPU time structure and energy deposition in NCD foils. We analyze changes to the foil with an RGA, FLIR camera, faraday cup, high definition photography, SEM, and Raman spectroscopy. We examine failure mechanisms for foils subjected to equivalent PPU conditions. Preliminary results have shown characteristic signs of foil thinning and different failure mechanisms between the electron gun and SNS beam line. Additionally, membrane cantilever structures have been synthesized and characterized to understand the material properties of the NCD. Finally, finite element thermal simulations of the suspended diamond foils have been performed, which will be used to assess and direct future foil modifications.
 
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WEZBA5 Development of a Marx Modulator for FNAL Linac 653
WEPLM45   use link to see paper's listing under its alternate paper code  
 
  • T.A. Butler, F.G. Garcia, M.R. Kufer, K.S. Martin, H. Pfeffer
    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.
A Marx-topology modulator has been designed and developed at the Fermi National Accelerator Laboratory under the Proton Improvement Plan (PIP). This modulator replaces the previous triode hard-tube design, increasing reliability, lowering operational costs, and maintaining waveform accuracy. The Marx modulator supplies the anode of the 7835 VHF power triode tube with a 35 kV, 375 Amp, 460 µs pulse at 15 Hz. It consists of 54 individual Marx cells, each containing a 639 µF capacitor charged to 900 Volts, combined in series with IGBT switches to create the desired output waveform. This requires variable rise and fall times, flattening of capacitive droop, and feedforward beam loading compensation. All five 201.25 MHz RF systems have been upgraded to Marx modulators to ensure continued operation of the linear accelerator.
 
slides icon Slides WEZBA5 [15.252 MB]  
poster icon Poster WEZBA5 [3.029 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEZBA5  
About • paper received ※ 28 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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WEZBA6 A 100 kW 1.3 GHz Magnetron System with Amplitude and Phase Control 656
 
  • M.E. Read, T. Bui, G. Collins, R.L. Ives
    CCR, San Mateo, California, USA
  • B.E. Chase, J. Reid
    Fermilab, Batavia, Illinois, USA
  • J.R. Conant, C.M. Walker
    CPI, Beverley, Massachusetts, USA
 
  Funding: United States Department of Energy Grant No. DE-SC0011229.
Calabazas Creek Research, Inc., Fermilab, and Communications & Power Industries, LLC, developed a 100 kW peak, 10 kW average, 1.3 GHz, magnetron-based, RF system for driving accelerators. Efficiency varied between 81% and 87%. Phase locking uses a novel approach that provides fast amplitude and phase control when coupled into a superconducting accelerator cavity [1]. The system was successfully tested at Fermilab and produced 100 kW in 1.5 ms pulses at a repetition rate of 2 pps. A locking bandwidth of 0.9 MHz was achieved with a drive signal of 269 W injected through a 4 port circulator. The phase locking signal was 25 dB below the magnetron output power. The spectrum of the phase locked magnetron was suitable for driving accelerator cavities. Phase modulation was demonstrated to 50 kHz (the limit of the available driver source). The average power was limited by available conditioning time. Scaling indicates 42 kW of average power should be achievable. Estimated cost is less than $1/Watt of delivered RF power, exclusive of power supplies or modulators. System design and performance measurements will be presented.
[1] B. Chase, R. Pasquinelli, E. Cullerton, P. Varghese, "Precision Vector Control of a Superconducting RF Cavity driven by an Injection Locked Magnetron," Jou. of Instrumentation, Vol. 10 March 2015.
 
slides icon Slides WEZBA6 [2.515 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEZBA6  
About • paper received ※ 27 August 2019       paper accepted ※ 04 September 2019       issue date ※ 08 October 2019  
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WEPLM47 Analysis of High Field Q-Slope (HFQS) Causes and Development of New Chemical Polishing Acid 699
SUPLS04   use link to see paper's listing under its alternate paper code  
 
  • D. Luo, E.S. Metzgar, L. Popielarski, K. Saito, S.M. Shanab, G.V. Simpson
    FRIB, East Lansing, Michigan, USA
  • T. Nakajima, I. Nasu, J. Taguchi
    Nomura Plating Co, Ltd., Osaka, Japan
 
  Funding: U.S. National Science Foundation under Grant PHY-1565546.
In our previous studies of High Field Q-slope (HFQS) we have concluded that nitrogen contamination from the nitric acid is the main cause of the degradation of the Q in buffered chemical polished cavities. Our conclusion is made based on previously unresolved phenomena which are found from huge amount of published cavity test data, include fine grain, large grain and single crystal cavities treated with EP and BCP. According to this analysis, we have started developing new nitrogen-free chemical polishing acid. Hydrogen peroxide with HF mixture was reported able to react with Nb, and there’s no extra element contamination in it, so we replace the conventional BCP with this mixture to start our study. In this paper, some Nb coupon sample results with new acid will be reported. We complete the first step of developing the new acid and we got the Nb finish roughness no worse than conventional BCP.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM47  
About • paper received ※ 13 September 2019       paper accepted ※ 04 December 2019       issue date ※ 08 October 2019  
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WEPLM49 New RF System for First Drift Tube Linac Cavity at LANSCE 703
 
  • J.T.M. Lyles, R.E. Bratton, G. Roybal, M. Sanchez Barrueta, G.M. Sandoval, Jr., D.J. Vigil, J.E. Zane
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Work supported by the United States Department of Energy, NNSA, under contract 89233218CNA000001
From 2014-2016, the three highest power 201 MHz power amplifier (PA) systems were replaced at the Los Alamos Neutron Science Center 100 MeV DTL. The initial DTL cavity provides 4.25 MeV of energy gain and has been powered by a Photonis (RCA) 4616 tetrode driving a 7835 triode PA for over 30 years. It consumes 110 kW of electrical power for tube filaments, power supplies and anode modulator. The modulator is not required with modern tetrode amplifiers. In 2020 we plan to replace this obsolete 6 tube transmitter with a design using a single tetrode PA stage without anode modulator, and a 20 kW solid-state driver stage. This transmitter needs to produce no more than 400 kW, and will use a coaxial circulator. Cooling water demand will reduce from 260 to 70 gal/min of pure water. High voltage DC power comes from the same power supply/capacitor bank that supplied the old system. The old low-level RF controls will be replaced with digital LLRF with learning capability for feedforward control, I/Q signal processing, and PI feedback. All high power components have been assembled in a complete mockup system for extended testing. Installation of the new RF system begins in January of 2020.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM49  
About • paper received ※ 28 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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WEPLM50 Beam Driven Bimodal Cavity Structure for High Gradient Acceleration 707
 
  • X. Chang, Y. Jiang, S.V. Shchelkunov
    Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
  • J.L. Hirshfield
    Omega-P, Inc., New Haven, Connecticut, USA
 
  Funding: Supported by USA National Science Foundation, Award #1632588
Abstract: Research aiming to increase the RF breakdown threshold in electron/positron accelerators is being conducted at the Yale University Beam Physics Laboratory. Our two-beam accelerator approach employs a beam driven bimodal cavity structure. This cavity includes (i) two modes excited by the drive beam, with the higher mode frequency three times that of the fundamental TM010 mode; (ii) a low-current accelerated beam and high-current drive beam traversing the same cavity structure. This approach has the potential advantages of (a) operating at higher acceleration gradient with lower breakdown and pulsed heating rates than that of a single-mode cavity structure at the same acceleration gradient, due to the spatiotemporal field distribution properties in the bimodal cavities; and (b) obtaining high accelerating gradient with a low energy drive beam. Recent progress in simulations and work towards an experimental test stand is presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM50  
About • paper received ※ 23 August 2019       paper accepted ※ 03 September 2019       issue date ※ 08 October 2019  
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WEPLM51 Ka-Band High Power Harmonic Amplifier for Bunch Phase-Space Linearization 710
 
  • X. Chang, Y. Jiang, S.V. Shchelkunov
    Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
  • J.L. Hirshfield
    Omega-P, Inc., New Haven, Connecticut, USA
 
  Funding: Supported by USA National Science Foundation, Award #1632588
Abstract: A future European light source CompactLight is being proposed to extend FEL operation further into the x-ray region than other light sources by using a linac operating at X-band (12 GHz) with a short Ka-band (36 GHz) section for linearizing bunch phase space. The Ka-band system requires a high-power RF amplifier, synchronized with the main X-band source. We report here on design of a third-harmonic klystron amplifier for this application. Our design employs a four-cavity system with a multi-cell extended interaction output cavity. Initial simulation results indicate that more than 10 MW of 36-GHz power can be obtained with an efficiency exceeding 20%, and with 12-GHz drive power of 30 W. A preliminary design for a proof-of-principal experimental test of this concept is described
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM51  
About • paper received ※ 23 August 2019       paper accepted ※ 05 September 2019       issue date ※ 08 October 2019  
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WEPLM52 Recent Developments of Nb3Sn at Jefferson Lab for SRF Accelerator Application 713
SUPLS05   use link to see paper's listing under its alternate paper code  
 
  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
 
  Funding: U.S. Department of Energy, Office of Science, Office of Nuclear Physics.
The desire to reduce the construction and operating costs of future SRF accelerators motivates the search for alternative, higher-performing materials. Nb3Sn (Tc ~ 18.3 K and Hsh ~ 425 mT) is the front runner. However, tests of early Nb3Sn-coated cavities encountered strong Q-slopes limiting the performance. Learnings from studies of coated materials related to cavity performance prompted significant changes to the coating process. It is now possible to routinely produce slope-free single-cell cavities having Q0 ≥ 2×1010 at 4 K and > 4×1010 at 2 K up to the accelerating gradient in excess of 15 MV/m at its best. Obtaining similar results in five-cell cavities is a current goal to test them under an accelerator environment. This contribution discusses recent developments at Jefferson Lab.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM52  
About • paper received ※ 27 August 2019       paper accepted ※ 31 August 2019       issue date ※ 08 October 2019  
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WEPLM53 50 kW CW Multi-Beam Klystron 717
 
  • S.V. Shchelkunov
    Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
  • J.L. Hirshfield, V.E. Teryaev
    Omega-P, Inc., New Haven, Connecticut, USA
 
  Funding: Funded by the US Department of Energy; grant DE-SC-0018471.
Main components, which are the electron gun, cavity-chain, magnetic system, and partially- grounded depressed four-stage collector, of a novel klystron were conceptually designed. This klystron is to deliver 50 kW CW at 952.6 MHz and to serve as a microwave power source for ion acceleration at the Electron Ion Collider (EIC) being developed at Thomas Jefferson National Accelerator Facility. The efficiency is 80%, a number to which the power consumption by the solenoid and filament are already factored in. The tube is a combination of proven technologies put together: it uses multiple beams to have its perveance low to boost beam-power to RF-power efficiency. It uses a partially grounded depressed collector to recover energy thereby increasing the overall efficiency. A low operating voltage of 14kV makes the tube more user-friendly avoiding need for costly modulators and oil insulation. A sectioned solenoid is used to insure superb beam-matching to all components downstream of the electron gun, increasing the tube performances. Details of the components designs will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM53  
About • paper received ※ 14 August 2019       paper accepted ※ 02 September 2019       issue date ※ 08 October 2019  
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WEPLM56 Development of Helium Gas Charge Stripper with Plasma Window 720
 
  • J. Gao, F. Marti
    FRIB, East Lansing, Michigan, USA
  • A. Lajoie
    NSCL, East Lansing, Michigan, USA
 
  Funding: This work is supported by NSF Award PHY-1565546.
The cascade arc discharge, also called "plasma window", was suggested to be used as an interface to provide an effective separation between atmosphere and vacuum [1]. As suggested by Thieberger and Hershcovitch at Facility for Rare Isotope Beams (FRIB) workshop in 2009, helium plasma window offers an alternative to a large pumping system used in helium gas charge stripper for high intensity heavy ion beam accelerator facilities [2]. In this report, we present the recent progress on the development of helium plasma window with both 6mm and 10 mm diameter apparatus [3]. The size dependent sealing performance of helium plasma window has been investigated. Various diagnostics tools have been developed to improve our understanding of underlying physics. Over 140 hours continuous unattended operation of helium plasma window in recirculating gas system has been achieved, which suggests our system to be a feasible charge stripper solution for heavy ion beam accelerators. We also discuss anticipated future developments of plasma window.
[1] A. Hershcovitch, Phys. Plasma 5, 2130 (1998).
[2] H. Imao, et al., Phys. Rev. ST Accel. Beams 15, 123501 (2012).
[3] A. LaJoie, J. Gao and F. Marti, IEEE Transactions on Plasma Science (2019)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM56  
About • paper received ※ 27 August 2019       paper accepted ※ 04 September 2019       issue date ※ 08 October 2019  
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WEPLM57 200 kW, 350 - 700 MHz RF Sources using Multiple Beam Triodes 724
 
  • R.L. Ives, T. Bui, D. Marsden, M.E. Read
    CCR, San Mateo, California, USA
  • B. Henderson, L. Higgins, R. Ho
    CPI, Palo Alto, California, USA
 
  Funding: U.S. Department of Energy Grant No. DE-SC0018838
Calabazas Creek Research, Inc. and Communications & Power Industries, LLC are developing multiple beam triodes to produce more than 200 kW of RF power at extremely low cost and efficiencies exceeding 85%. RF power is achieved by installing the triode inside coaxial input and output cavities at the desired frequency. The multiple beam triodes developed in this program will provide RF power from 350 MHz to 700 MHz using the appropriate, tuned, resonant cavities. This program is using eight grid-cathode assemblies to achieve 200 kW with a target efficiency exceeding 80%. A 350 MHz RF source would be approximately 36 inches high, 18 inches in diameter and weigh approximately 150 pounds. This is significantly smaller than any other RF source at this frequency and power level. The gain is limited to approximately 14 dB, so a single beam triode-based source will serve as a driver. The combined cost and efficiency will still exceed the performance of other comparable RF sources, including solid state sources. Design issues, include grid cooling, uniformity of RF electric fields on the grids, and efficiency, will be discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM57  
About • paper received ※ 27 August 2019       paper accepted ※ 04 September 2019       issue date ※ 08 October 2019  
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WEPLM60 Fast Sn-Ion Transport on Nb Surface for Generating NbxSn Thin Films and XPS Depth Profiling 727
 
  • Z. Sun, M. Liepe, J.T. Maniscalco, T.E. Oseroff, R.D. Porter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • X. Deng
    University of Virginia, Charlottesville, Virginia, USA
  • D. Zhang
    Cornell University, Ithaca, New York, USA
 
  Funding: U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams
In this work, we propose and demonstrate a fast and facile approach for NbxSn thin film deposition through the ion exchange reaction. By simply dipping a tin precursor on the Nb substrate surface, a ~600 nm thin film is generated due to the electronegativity differ-ence between Sn and Nb. Through X-ray photoelec-tron spectroscopy (XPS) depth profiling, the composi-tional information as a function of film thickness was obtained. Results showed a Sn layer on the film sur-face, Sn-rich and Nb-rich NbxSn layers as the majority of the film, and a ~60 nm Nb3Sn layer at the film/substrate interface. Quantitative analysis con-firmed stoichiometric Nb/Sn ratio for the Nb3Sn layer. This deposition method is demonstrated to be an alter-native choice for Nb3Sn film growth.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM60  
About • paper received ※ 05 September 2019       paper accepted ※ 15 September 2019       issue date ※ 08 October 2019  
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WEPLM62 First Cold Test Results of a Medium-Beta 644 MHz Superconducting 5-Cell Elliptical Cavity for the FRIB Energy Upgrade 731
SUPLS07   use link to see paper's listing under its alternate paper code  
 
  • K.E. McGee, B.W. Barker, K. Elliott, A. Ganshyn, W. Hartung, S.H. Kim, P.N. Ostroumov, J.T. Popielarski, A. Taylor, C. Zhang
    FRIB, East Lansing, Michigan, USA
  • M.P. Kelly, T. Reid
    ANL, Lemont, Illinois, USA
 
  Funding: Work supported by Michigan State University.
The superconducting linac for the Facility for Rare Isotope Beams (FRIB) will accelerate ions to 200 MeV per nucleon, with the possibility of a future energy upgrade to 400 MeV per nucleon via additional cavities. A 5-cell superconducting β = 0.65 elliptical cavity was designed for this purpose. Two unjacketed 5-cell niobium cavities were fabricated; the first of these was Dewar tested in February 2019. The surface preparation was bulk electropolishing (EP, 150 µm), hydrogen degassing (600°C, 10 hours), light EP (20 µm), clean-room high-pressure water rinsing, and in-situ baking (120°C, 48 hours). We achieved Q0 = 2·1010, equivalent to Rs = 10 nΩ, at the design gradient of 17.5 MV/m. The cavity was tested in a newly refurbished FRIB test Dewar, equipped with a variable input coupler.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM62  
About • paper received ※ 02 September 2019       paper accepted ※ 19 November 2019       issue date ※ 08 October 2019  
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WEPLM63 Development of a Secondary Sn Source for Nb3Sn Coating of Half-Wave Coaxial Resonator 735
SUPLS09   use link to see paper's listing under its alternate paper code  
 
  • J.K. Tiskumara, J.R. Delayen, H. Park
    ODU, Norfolk, Virginia, USA
  • G.V. Eremeev
    JLab, Newport News, Virginia, USA
  • U. Pudasaini
    The College of William and Mary, Williamsburg, Virginia, USA
 
  Superconducting thin films have the potential of reducing the cost of particle accelerators. Among the potential materials, Nb3Sn has a higher critical temperature and higher critical field compared to niobium. Sn vapor diffusion method is the preferred technique to coat niobium cavities. Although there are several thin-film-coated basic cavity models that are tested at their specific frequencies, the Half-wave resonator could provide us data across frequencies of interest for particle accelerators. With its advanced geometry, increased area, increased number of ports and hard to reach areas, the half-wave resonator needs a different coating approach, in particular, a development of a secondary Sn source. We are commissioning a secondary Sn source in the coating system and expand the current coating system at JLab to coat complex cavity models.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM63  
About • paper received ※ 27 August 2019       paper accepted ※ 06 September 2019       issue date ※ 08 October 2019  
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WEPLM64 High Dynamic Voltage Range Studies of Piezoelectric Multilayer Actuators at Low Temperatures 739
SUPLS01   use link to see paper's listing under its alternate paper code  
 
  • C. Contreras-Martinez
    FRIB, East Lansing, Michigan, USA
  • Y.M. Pischalnikov, J.C. Yun
    Fermilab, Batavia, Illinois, USA
 
  Piezo actuators are used for resonance control in superconducting linacs. In high accelerating gradients linacs, such as those operated in a pulsed mode, the piezos require a large operating voltage. This is due to the Lorentz forced detuning which causes a large frequency shift and is compensated with an active piezo-tuning system. In this high dynamic voltage range the piezo is expected to warm up drastically due to it being in an insulated vacuum. This study characterizes the dielectric properties (capacitance, dielectric losses), the piezo stroke (from geophone), and thermal properties such as heating. Results obtained in the temperature range of 20K to 300K will be presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM64  
About • paper received ※ 28 August 2019       paper accepted ※ 31 August 2019       issue date ※ 08 October 2019  
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WEPLM66 Microphonics Studies at STC in Fermilab 743
 
  • C. Contreras-Martinez
    FRIB, East Lansing, Michigan, USA
  • Y.M. Pischalnikov, W. Schappert, A.I. Sukhanov, J.C. Yun
    Fermilab, Batavia, Illinois, USA
 
  The spoke test cryostat is used to qualify the 325 MHz single spoke resonators at Fermilab (FNAL). During these tests a large detuning on the cavity was observed. The data acquisition for continuous captures were based on measurements from the piezoelectric actuators. A com-parison of the cavity vibrations measured with RF signal from the cavity and piezoelectric actuator signals are shown. The effects of microphonics on the cavity are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM66  
About • paper received ※ 28 August 2019       paper accepted ※ 31 August 2019       issue date ※ 08 October 2019  
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WEPLM67 Optimization of a Single-Cell Accelerating Structure for Rf Breakdown Test With Short Rf Pulses 747
 
  • M.M. Peng, J. Shi
    TUB, Beijing, People’s Republic of China
  • M.E. Conde, G. Ha, C.-J. Jing, W. Liu, J.G. Power, J. Seok, J.H. Shao, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
 
  RF breakdown is one of the major limitations to achieve high gradient acceleration for future structure-based normal conducting linear colliders. Previous statistic research shows that the breakdown rate is proportional to Ea30 * tp5, which indicates that the accelerating gradient Ea could be improved by using shorter RF pulses (tp). An X-band 11.7~GHz metallic single-cell structure has been designed for RF breakdown study up to 273~MV/m using short pulses (~3ns) generated by a 400~MW power extractor at Argonne Wakefield Accelerator (AWA) facility. The structure has also been scaled to 11.424~GHz for the long pulse (100-1500~ns) breakdown study driven by a klystron and a pulse compressor at Tsinghua X-band High Power Test-stand (TPoT-X), with the gradient up to 246~MV/m with 200~MW input power.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM67  
About • paper received ※ 05 September 2019       paper accepted ※ 26 November 2019       issue date ※ 08 October 2019  
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WEPLM68 Design of a Dielectric-Loaded Accelerator for Short Pulse High Gradient Research 751
 
  • M.M. Peng, J. Shi
    TUB, Beijing, People’s Republic of China
  • M.E. Conde, G. Ha, C.-J. Jing, W. Liu, J.G. Power, J. Seok, J.H. Shao, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
 
  The short-pulse two-beam acceleration approach is a promising candidate to meet the cost and luminosity requirements for future linear colliders. Dielectric-loaded structure has been intensely investigated for this approach because of its low fabrication cost, low RF loss, and potential to withstand GV/m gradient. An X-band 11.7~GHz dielectric-loaded accelerator (DLA) has been designed for high power test with short RF pulses (3~ns) generated from a power extractor driven by high charge bunches at Argonne Wakefield Accelerator (AWA) facility. The gradient is expected to be over 100~MV/m with the maximum input power of 400~MW.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM68  
About • paper received ※ 05 September 2019       paper accepted ※ 27 November 2019       issue date ※ 08 October 2019  
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WEPLM70 FRIB Tuner Performance and Improvement 755
 
  • J.T. Popielarski, W. Chang, C. Compton, W. Hartung, S.H. Kim, E.S. Metzgar, S.J. Miller, K. Saito, J.F. Schwartz, T. Xu
    FRIB, East Lansing, Michigan, USA
 
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
The Facility for Rare Isotope Beams (FRIB) is under construction at Michigan State University (MSU). The FRIB superconducting driver linac will accelerate ion beams to 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 cryomodules for β = 0.041, 0.085, and 0.29 have been completed and certified; 32 out of 49 cryomodules are certified via bunker test (as of March 2019). FRIB QWR cavities have a demountable niobium tuning plate which uses a warm external stepper motor and the FRIB HWR cavities use pneumatic actuated bellows. Progress on the preparation and performance of the tuners is presented in this paper along with improvements made to ensure meeting frequency specification.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM70  
About • paper received ※ 26 September 2019       paper accepted ※ 19 November 2019       issue date ※ 08 October 2019  
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WEPLM71 Thermal Performance of FRIB Cryomodules 759
 
  • M. Xu, W. Chang, C. Compton, A. Ganshyn, S.H. Kim, S.J. Miller, J.T. Popielarski, K. Saito, T. Xu
    FRIB, East Lansing, Michigan, USA
 
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511.
Now SRF cavity development is advancing high-Q/high gradient by nitrogen doping, infusion, or the new low temperature bake recipe. Once cavity dynamic loss is reduced, the static heat load of the cryomodule will be of concern from the cryogenic plant capability point of view. FRIB gives us a good chance to statistically compare the cryogenic plant design and the measured results, along with a thought for future updated cryomodule design using a low/medium beta cryomodule. FRIB cryomodules have two cooling lines: 4.5 K for solenoids and 2K for cavities. The boil-off liquid helium method was used to measure the cryomodule’s heat load. So far, FRIB has completed certification testing (bunker tests) on 39 of 49 cryomodules (80%). This paper reports the static heat load measurement results, which are important for future FRIB upgrades to estimate remaining cryogenic capability. The cryomodule’s evolution related to heat load is introduced too.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM71  
About • paper received ※ 05 September 2019       paper accepted ※ 15 September 2019       issue date ※ 08 October 2019  
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WEPLM72 Design of a High-Gradient S-Band Annular Coupled Structure 762
 
  • B. Mustapha, A. Abogoda, A. Barcikowski, R.L. Fischer, A. Nassiri
    ANL, Lemont, Illinois, USA
 
  Funding: This work was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357 through ANL’s LDRD program.
At Argonne, we have recently developed a conceptual design for a compact linear accelerator for ion beam therapy named ACCIL [1]. A linac-based ion-beam therapy facility offers many advantages over existing synchrotron based facilities. In addition to the reduced footprint, ACCIL offers more flexibility in beam tuning, including pulse-per-pulse energy and intensity modulation and fast switching between ion species. Essential to the compactness of the ACCIL linac are high-gradient structures for low to intermediate velocity ions, capable of accelerating fields of ~ 50 MV/m. For this purpose, we have designed an S-band annular-coupled structure (ACS). An ACS has the desired qualities of high electric field limit, high shunt-impedance, large area for magnetic coupling and good cooling capacity, making it a very promising candidate for high-gradient operations. We here present the optimized RF design for a β ~ 0.4 ACS.
* P. Ostroumov, et al., "Compact Carbon Ion Linac", Proceedings of NAPAC2016, Oct 10-14 2016, Chicago, IL
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM72  
About • paper received ※ 04 October 2019       paper accepted ※ 16 November 2020       issue date ※ 08 October 2019  
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WEPLM73 Bunker Testing of FRIB Cryomodules 765
 
  • W. Chang, S. Caton, A. Ganshyn, W. Hartung, S.H. Kim, B. Laumer, H. Maniar, J.T. Popielarski, K. Saito, M. Xu, T. Xu, C. Zhang, S. Zhao
    FRIB, East Lansing, Michigan, USA
 
  The FRIB superconducting driver Linac requires 104 quarter-wave resonators (QWRs, β = 0.041, 0.085), 220 half-wave resonators (HWRs, β = 0.29, 0.53), and 74 superconducting solenoid packages. Resonators and solenoids are assembled into cryomodules; 4 accelerating and 2 matching cryomodule types are required. Each cryomodule undergoes cryogenic and RF testing in a bunker prior to installation in the tunnel. The cryomodule test verifies operation of the cavities, couplers, tuners, solenoid packages, magnetic shield, and thermal shield at 4.3 K and 2 K. All of the required cryomodules for β = 0.041, 0.085, and 0.29 have been tested and certified. As of May 2019, five of the β = 0.53 cryomodules have been certified; the remaining modules are being assembled or are in the queue for testing. Cryomodule test results will be presented, including cavity performance (accelerating gradient, field emission X-rays, multipacting conditioning); solenoid package operation (current, current-lead cooling flow rate); and cryomodule heat load (static and dynamic).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEPLM73  
About • paper received ※ 06 September 2019       paper accepted ※ 16 November 2020       issue date ※ 08 October 2019  
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THYBB1
16 Tesla Magnets for the Future Circular Collider Proton-Proton  
 
  • J. Munilla
    CIEMAT, Madrid, Spain
 
  One of the main R&D efforts being made in the framework of the FCC-hh project is the development of the 16 Tesla dipole magnets. The talk will describe the recent achievements in this area.  
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THYBB2
Additive Manufacturing of Electrical and Thermal Devices: Challenges and Opportunities  
 
  • P.R. Carriere, P. Frigola, A.Y. Murokh
    RadiaBeam, Santa Monica, California, USA
  • D. Gamzina
    SLAC, Menlo Park, California, USA
  • T. Horn
    NCSU, Raleigh, North Carolina, USA
 
  Metal-based, powder-bed additive manufacturing represents the convergence of three mature technologies: powder metallurgy, digital controls and high-power electron or laser beam optics. The aero, defense and medical industries have significantly benefited from this rapidly-evolving ecosystem, as it offers expanded design opportunities, part consolidation and reduced lead times. These applications are generally structural, utilizing titanium, aluminum, nickel or iron based alloys. Oxygen-free copper represents a significantly more challenging material because it’s intrinsic properties ( i.e. thermal conductivity) as well as the purity requirements of the final part. Furthermore, accelerator components are based on internal features, which complicated downstream processing. In this presentation, the general AM industry status will be reviewed, highlighting the successful use-cases from other industries. The challenges of printing in Cu will be described from a fundamentals perspective. Finally, the current status of Cu printing will be described, highlighting current progress and areas of future investigation.  
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THYBB3 Compact 1 MeV Electron Accelerator 942
 
  • S.V. Kuzikov
    IAP/RAS, Nizhny Novgorod, Russia
  • S.P. Antipov, P.V. Avrakhov
    Euclid TechLabs, LLC, Solon, Ohio, USA
 
  The cost of the accelerating structure in modern medical accelerators and industrial linacs is substantial. This comes to no surprise, as the accelerating waveguide is a set of diamond-turned copper resonators brazed together. Such a multistep manufacturing process is not only expensive, but also prone to manufacturing errors, which decrease the production yield. In the big picture, the cost of the accelerating waveguide precludes the use of accelerators as a replacement option for radioactive sources. Here we present a new cheap brazeless electron accelerating structure made out of two copper plates tightened together by means of an additional stainless steel plate. This additional plate, having sharp blades, is aimed to provide vacuum inside the whole system. The designed X-band 1 MeV structure consists of eight different length cells and accelerates field-emitted electrons from copper cathode. The structure is fed by 9 GHz magnetron which produces 240 kW, 1 µs pulses. The average gradient is as high as 10.6 MV/m, maximum surface fields do not exceed 50 MV/m.  
slides icon Slides THYBB3 [19.559 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THYBB3  
About • paper received ※ 27 August 2019       paper accepted ※ 15 September 2019       issue date ※ 08 October 2019  
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THYBB4
High-Gradient Tests of W-Band Accelerating Structures  
WEPLM46   use link to see paper's listing under its alternate paper code  
 
  • M.A.K. Othman, V.A. Dolgashev, A.A. Haase, E.A. Nanni, J. Neilson, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • S. Jawla, J.F. Picard, R.J. Temkin
    MIT/PSFC, Cambridge, Massachusetts, USA
  • S.C. Schaub
    MIT, Cambridge, Massachusetts, USA
  • B. Spataro
    INFN/LNF, Frascati, Italy
 
  Funding: This work was supported by Department of Energy contract DE-AC02-76SF00515 (SLAC) and grant DE-SC0015566 (MIT). This work was also supported by NSF grants PHY-1734015.
There is an ongoing interest in linear accelerators operating at 100s of GHz and THz frequencies due to their small size and potentially high efficiency. Vacuum RF breakdown is one of the fundamental factors limiting performance of these linacs. Accordingly, study of RF breakdown physics in mm-wave high gradient accelerating structures is needed, which includes understanding of dependencies of the breakdown rate on electromagnetic, geometric, and material properties. In our previous work, we have tested beam-driven 100 GHz and 200 GHz metallic accelerating structures. In this work we report results of high power tests of a 110 GHz single-cell standing wave accelerating cavity powered by a 1 MW gyrotron. The RF power is coupled into the accelerating structure using a "Gaussian to TM01" mode converter. In order to characterize high gradient behavior of the cavity, including the RF breakdown probability, we have measured RF signals and field-emitted currents. The cavity is driven by 10 ns, 100s of kilowatt pulses. These short pulses were cut from microsecond-long gyrotron pulses using a fast optical switch, with accelerating gradients up to 150 MV/m.
 
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THYBB5
Nanosecond RF Power Switch for Gyrotron-Driven Millimeter-Wave Accelerators  
 
  • S.V. Kutsaev, J. Condori, B.T. Jacobson, M. Ruelas, A.Yu. Smirnov
    RadiaBeam, Santa Monica, California, USA
  • V.A. Dolgashev, B.T. Jacobson, E.A. Nanni
    SLAC, Menlo Park, California, USA
  • A.Y. Murokh
    RadiaBeam Systems, Santa Monica, California, USA
  • J.F. Picard
    MIT/PSFC, Cambridge, Massachusetts, USA
  • S.C. Schaub
    MIT, Cambridge, Massachusetts, USA
 
  Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under SBIR DE-SC0013684.
The development of novel mm-wave accelerating structures with > 200 MV/m gradients offers a promising path to reduce the cost and footprint of future TeV-scale linear colliders, as well as linacs for industrial, medical and security applications. The major factor limiting accelerating gradient is vacuum RF breakdown. The probability of such breakdowns increases with pulse length. For reliable operation, millimeter-wave structures require nanoseconds long pulses at the megawatt level. This power is available from gyrotrons, which have a minimum pulse length on the order of microseconds. In this paper, we will describe the laser-based RF switch capable of selecting 10 ns long pulses out of the microseconds long gyrotron pulses, thus enabling the use of the gyrotrons as power sources for mm-wave high gradient linac. The principle of operation of this device and its achieved parameters will be discussed. We will also report on the experimental demonstration of the RF switch with the high power gyrotron at the Massachusetts Institute of Technology.
 
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THYBB6
Multi-TW Picosecond Long-Wave Infrared Laser for Particle Acceleration at ATF  
 
  • M.N. Polyanskiy, M. Babzien, M.A. Palmer, I. Pogorelsky
    BNL, Upton, New York, USA
 
  Favorable wavelength scaling makes high peak-power lasers operating in the long-wave infrared (LWIR) spectral range (8 14 µm) attractive for several promising schemes of laser particle acceleration. For instance, because of the scaling of the ponderomotive force and the critical plasma density as λ2 and 1/λ2 respectively, LWIR lasers can drive plasma wakes in laser wakefield accelerators much more efficiently than near-IR lasers while producing much bigger trapping volumes. Amplification of a picosecond pulse in high-pressure CO2 laser amplifiers is presently the only method of generating a terawatt peak power in LWIR. We recently achieved a 5-TW operation in quasi-single 2-ps pulses at 9.2 μm at 0.05 Hz repetition rate and we are currently working on reducing the pulse duration to below a picosecond as required for the realization of LWFA acceleration in the bubble regime.  
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THAHC0
Awards Session Welcome  
 
  • T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
 
  Awards Session Welcome  
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THAHC1
2019 APS DPB Outstanding Doctoral Thesis Award - Relativistic Plasmonics in High Intensity Laser-Solid Interactions  
 
  • G. Cantono
    Lund University, Lund, Sweden
  • T. Ceccotti
    CEA/DRF, Gif-sur-Yvette, France
  • L. Fedeli
    LIDYL, Gif sur Yvette, France
  • A. Macchi
    INO-CNR, Pisa, Italy
 
  I will present the results of my PhD project, centred on the experimental study of the radiation sources raised by the excitation of propagating Surface Plasmons (SPs) on solid targets irradiated by highly intense, short laser pulses. This work, originally aiming at the investigation of how to enhance the laser-target coupling with micro-structured periodic targets, encourages both the development of a suitable theory for SPs in such a non-linear regime, and the possibility to exchange ideas and applications between classical plasmonics and the domain of relativistic laser-plasma acceleration*. Our experiments show that the SP excitation is correlated to the acceleration of dense electron bunches of few MeV of energies along the surface of the laser-irradiated target**, and to the emission in the same direction of high order harmonics of the laser frequency***. Both emissions can be optimized by an appropriate tuning of the laser-target parameters (incidence angle, target profile and density). In addition, 2D Particle-In-Cell simulations reveal a spatio-temporal correlation between accelerated electrons and harmonics that gives insight on the generation mechanism of the XUV beam.
* Phys. of Plasmas 26, 042114 (2019).
** Phy. Rev. Lett. 116, 015001 (2016). Phys. of Plasmas 25, 031907 (2018).
*** Phys. Rev. Lett. 120, 264803 (2018). Appl. Phys. Lett. 110, 051103 (2017).
 
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THAHC4
IEEE NPSS Award  
 
  • D.B. Cesar
    SLAC, Menlo Park, California, USA
 
  IEEE NPSS Awards  
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THAHC6
Particle-in-Cell Simulations of Plasma Production in C100 SRF Cavity for in Situ Cleaning  
 
  • J.B. Leddy, J.R. Cary, D.M. Cheatham, D.N. Smithe
    Tech-X, Boulder, Colorado, USA
 
  Particle-in-cell simulations provide insight into the parameters of the plasma that can be used to remove impurities from superconducting radio frequency (SRF) cavity walls in situ. Surface contamination of the vessel walls can severely impact the achievable field strength. Therefore, efficient and effective cleaning of the cavity surfaces is necessary to maintain optimal acceleration gradients. In situ cleaning techniques involve generating plasma discharges that remove the impurities through chemical and mechanical processes*. The benefits of these techniques are to reduce the field emission and increase stability for devices with complex geometries without the need for disassembly. Theoretical methods have emerged to increase the effectiveness of the plasma discharge cleaning; however, there is an inherent risk when attempting new methods experimentally. We have performed particle-in-cell simulations of the C100 cavity including ionization, recombination, and scattering interactions to explore the parameters of the plasma generated via EM signal. These properties provide an insight into the plasma generation and its predicted effectiveness at removing impurities.  
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FRXBB1 Rare Isotope Beams and High-power Accelerators 993
 
  • J. Wei
    FRIB, East Lansing, Michigan, USA
 
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511.
Facilities for rare isotope beams provide tools for nuclear science research and tools for applications ranging from fundamental nuclear structure and dynamics to societal benefits in medicine, energy, material sciences and national security. State-of-the-art rare isotope facilities can be based on an isotope separation on-line (ISOL) approach using mostly high-power proton beams striking a thick target where the isotopes are produced in the target, or an in-flight fragment separation (IF) approach using high-power heavy ion beams striking upon a thinner target where the isotopes continue out of the target followed by fragment separation. This tutorial class introduces high power hadron accelerators as driver machines for rare isotope production, summarizing the key design philosophy, physical and technical challenges, and current world-wide development status. As an example, the Facility for Rare Isotope Beams (FRIB) project is used to illustrate the process of establishing such facilities.
 
slides icon Slides FRXBB1 [41.291 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-FRXBB1  
About • paper received ※ 02 September 2019       paper accepted ※ 17 November 2020       issue date ※ 08 October 2019  
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FRCHC1
Superconducting Cavities for Quantum Computers  
 
  • A.S. Romanenko
    Fermilab, Batavia, Illinois, USA
 
  Superconducting quantum systems are currently at the leading edge of quantum information science (QIS), including quantum computing, as well as fundamental quantum physics experiments and particle physics search experiments. So far though the 3D superconducting cavities which were used in the field of QIS, had quality factors Q ~108, providing one of the primary limitations for the achievable useful quantum superposition (aka coherence) times. In this talk I will overview how the superconducting radio frequency (SRF) cavity expertise in accelerators can bring the field of QIS ahead by several orders of magnitude in coherence times, as well discuss the emerging Quantum Technology effort at Fermilab and the first record achievements in this area.  
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FRCHC4
Closing Session Presentation  
 
  • T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
 
  Closing Session Presentation  
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