THYBB —  Thursday Parallel Session 4   (05-Sep-19   10:30—12:30)
Chair: M.P. Kelly, ANL, Lemont, Illinois, USA
Paper Title Page
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.  
slides icon Slides THYBB1 [3.655 MB]  
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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.  
slides icon Slides THYBB2 [10.586 MB]  
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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 ※  
About • paper received ※ 27 August 2019       paper accepted ※ 15 September 2019       issue date ※ 08 October 2019  
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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.
slides icon Slides THYBB4 [4.501 MB]  
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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. Murokhpresenter
    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.
slides icon Slides THYBB5 [9.975 MB]  
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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.  
slides icon Slides THYBB6 [1.455 MB]  
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