Author: Dolgashev, V.A.
Paper Title Page
MOPAB152 High Power Tests of Brazeless Accelerating Structures 532
 
  • S.P. Antipov, P.V. Avrakhov, C.-J. Jing, S.V. Kuzikov
    Euclid TechLabs, Solon, Ohio, USA
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  • D.S. Doran, W. Liu, J.G. Power, J.H. Shao, E.E. Wisniewski
    ANL, Lemont, Illinois, USA
 
  Funding: DOE SBIR Grant #DE-SC0017749
A typical accelerating structure is a set of copper resonators brazed together. This multi step process is expensive and time consuming. In an effort to optimize production process for rapid prototyping and overall reduction of accelerator cost we developed a split block brazeless accelerating structure. In such structure the vacuum is sealed by the use of knife edges, similar to an industry standard conflat technology. In this paper we present high power tests of several different brazeless structures. First, an inexpensive 1 MeV accelerator powered by radar magnetron. Second, a high gradient power extractor tested at Argonne Wakefield Accelerator Facility. In this experiment a high charge electron beam generated a 180 MW peak power pulse. Finally, we report on high power testing of a brazeless x-band accelerating structure at SLAC.
 
poster icon Poster MOPAB152 [0.783 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB152  
About • paper received ※ 20 May 2021       paper accepted ※ 24 June 2021       issue date ※ 31 August 2021  
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MOPAB155 Magnetic Breakdowns in Side-Coupled X-Band Accelerating Structures 540
 
  • S.P. Antipov, P.V. Avrakhov, S.V. Kuzikov
    Euclid TechLabs, Solon, Ohio, USA
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  • C. Jing
    Euclid Beamlabs, Bolingbrook, USA
 
  Funding: DOE SBIR
Side coupled accelerating structures are popular in the industrial realizations of linacs due to their high shunt impedance and ease of tuning. We designed and fabricated a side-coupled X-band accelerating structure that achieved 133 MOhm/m shut impedance. This structure was fabricated out of two halves using a novel brazeless approach. The two copper halves are joined together using a stainless steel joining piece with knife edges that bite into copper. This structure had been tested at high power at SLAC National Accelerator Laboratory. The performance of the structure had been limited by magnetic breakdowns on the side-coupling cells. In this paper we will present results of the high gradient tests and after-test analysis. Scanning electron microscopy images show a typical magnetic-field induced breakdown.
 
poster icon Poster MOPAB155 [1.069 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB155  
About • paper received ※ 20 May 2021       paper accepted ※ 23 June 2021       issue date ※ 01 September 2021  
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MOPAB353 Design of a compact Ka-Band Mode Launcher for High-gradient Accelerators 1100
 
  • G. Torrisi, G.S. Mauro, G. Sorbello
    INFN/LNS, Catania, Italy
  • M. Behtouei, L. Faillace, B. Spataro, A. Variola
    INFN/LNF, Frascati, Italy
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  • L. Faillace, M. Migliorati
    Sapienza University of Rome, Rome, Italy
  • M. Migliorati
    INFN-Roma1, Rome, Italy
  • J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • G. Sorbello
    University of Catania, Catania, Italy
 
  In this work, we present the RF design of a table-top Ka-Band mode launcher operating at 35.98 GHz. The structure consists of a symmetrical 4-port WR28 rectangular-TE10-to-circular-TM01 mode converter that is used to couple a peak output RF power of 5 MW (pulse length up to 50 ns and repetition rate up to 100 Hz) in Ka-Band linear accelerator able to achieve very high accelerating gradients (up to 200 MV/m). Numerical simulations have been carried out with the 3D full-wave commercial simulator Ansys HFSS in order to obtain a preliminary tuning of the accelerating field flatness at the operating frequency f0=35.98 GHz. The main RF parameters, such as reflection coefficient, transmission losses, and conversion efficiency are given together with a verification of the field azimuthal symmetry which avoids dipole and quadrupole deflecting modes. To simplify future manufacturing, reduce fabrication costs, and also reduce the probability of RF breakdown, the proposed new geometry has "open" configuration. This geometry eliminates the flow of RF currents through critical joints and allows this device to be milled from metal blocks.  
poster icon Poster MOPAB353 [3.131 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB353  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 27 August 2021  
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THPAB170 RF Deflector Design for Rapid Proton Therapy 4086
 
  • E.J.C. Snively, G.B. Bowden, V.A. Dolgashev, Z. Li, E.A. Nanni, D.T. Palmer, S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  Funding: This work is supported by US Department of Energy Contract No. DE-AC02-76SF00515.
Pencil beam scanning of charged particle beams is a key technology enabling high dose rate cancer therapy. The potential benefits of high-speed dose delivery include not only a reduction in total treatment time and improvements to motion management during treatment but also the possibility of enhanced healthy tissue sparing through the FLASH effect, a promising new treatment modality. We present here the design of an RF deflector operating at 2.856 GHz for the rapid steering of 150 MeV proton beams. The design utilizes a TE11-like mode supported by two posts protruding into a pillbox geometry to form an RF dipole. This configuration provides a significant enhancement to the efficiency of the structure, characterized by a transverse shunt impedance of 68 MOhm/m, as compared to a conventional TM11 deflector. We discuss simulations of the structure performance for several operating configurations including the addition of a permanent magnet quadrupole to amplify the RF-driven deflection. In addition to simulation studies, we will present preliminary results from a 3-cell prototype fabricated using four copper slabs to accommodate the non-axially symmetric cell geometry.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB170  
About • paper received ※ 19 May 2021       paper accepted ※ 14 July 2021       issue date ※ 27 August 2021  
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