Author: Sorsher, S.
Paper Title Page
TUPB06 Design of Miniature Waveguides and Diamond Window Assembly for RF Extraction and Vacuum Isolation for the CWA 156
 
  • B.K. Popovic, S.H. Lee, S. Sorsher, K.J. Suthar, E. Trakhtenberg, G.J. Waldschmidt, A. Zholents
    ANL, Lemont, Illinois, USA
  • A.E. Siy
    UW-Madison, Madison, Wisconsin, USA
 
  Funding: This manuscript is based upon work supported by Laboratory Directed Research and Development (LDRD) funding from Argonne National Laboratory
This paper outlines the design of a diamond vacuum window and a millimeter wavelength (mmWave) waveguide assembly that will hold vacuum but still allow the mmWaves to propagate out of the structure for diagnosis and thermal management purposes. Currently under development at Argonne is a corrugated wakefield accelerator (CWA) that will operate at mmWave frequencies, with its fundamental mode of operation at 180 GHz, and relatively high power levels, up to 600 W. The fundamental mode needs to be extracted from the accelerator at approximately every 0.5 m to prevent the unwanted heating of the accelerator structure. Therefore, the structure is intentionally designed so this fundamental mode does not propagate further, instead it is transmitted through the waveguide assembly under vacuum and out via the vacuum window. As a result of the relatively high mmWave power densities, CVD diamond was chosen as the vacuum window material, due to its low electromagnetic losses, mechanical strength, and for its superior thermo-physical properties. Mechanically it is necessary to be able to hold the tight tolerances necessary for windows performance at millimeter wavelengths. Other mechanical difficulties involve assembly of the window due to CVD diamond material and preservation of ultra high vacuum even if the integrity of the CVD diamond window is somehow compromised.
 
poster icon Poster TUPB06 [0.386 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2020-TUPB06  
About • paper received ※ 26 July 2021       paper accepted ※ 05 October 2021       issue date ※ 02 November 2021  
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TUPB07 Vacuum Analysis of a Corrugated Waveguide Wakefield Accelerator 160
 
  • K.J. Suthar, S. Sorsher, E. Trakhtenberg, A. Zholents
    ANL, Lemont, Illinois, USA
 
  Funding: This is based upon work supported by LDRD funding from Argonne National Laboratory, provided by the Director, Office of Science, of the U.S. Department of Energy under contract DE-AC02-06CH11357.
The vacuum level in a 2 mm diameter, 0.5 m-long copper corrugated waveguide tube proposed* for a compact high repetition rate wakefield accelerator has been investigated. The analytical calculations have been found to be in good agreement with a result of computer modeling using a finite element method. A representative experiment has been conducted using a smooth copper tube with the same diameter as the corrugated tube and a 1/3 length of the corrugated tube. The vacuum level calculated for this experiment agrees well with the measurement.
*A. Zholentset et al., inProc. 9th International Particle Accelerator Conference (IPAC’18), Vancouver, BC, Canada, 29 April-04 May 2018, ser. IPAC Conference, pp. 1266’1268.
 
poster icon Poster TUPB07 [0.954 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2020-TUPB07  
About • paper received ※ 22 July 2021       paper accepted ※ 29 October 2021       issue date ※ 05 November 2021  
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TUPC05
Design and Fabrication of a Waveguide for Conductivity Measurement of Electroplated Copper at 170GHz - 200GHz  
 
  • A.E. Siy, N. Behdad, J.H. Booske
    UW-Madison, Madison, Wisconsin, USA
  • S.H. Lee, S. Sorsher, K.J. Suthar, E. Trakhtenberg, G.J. Waldschmidt, A. Zholents
    ANL, Lemont, Illinois, USA
 
  Funding: This work is supported by LDRD funding from Argonne National Laboratory, provided by the Director, Office of Science, of the U.S. Department of Energy under contract DE-AC02-06CH11357
Beam driven wakefield accelerators offer great potential for the realization of compact, low-cost x-ray free electron laser (XFEL) sources. Achieving high accelerating gradients in these devices requires the use of mm-wave RF structures which present a range of fabrication challenges due to their small size and tight dimensional tolerances. One promising technique for manufacturing these structures involves electroplating a mandrel with copper and subsequently dissolving the mandrel to leave behind the desired metal cavity. Because the resulting copper shell is electroplated, its purity, grain structure, and surface finish will be different from that of conventionally machined copper. Understanding the electrical and thermal performance of the electroformed components requires experimental measurement of the plated copper material properties. In this paper, an experiment for measuring the conductivity of electroplated copper at 170 GHz-200 GHz using a WR-5 waveguide meander is presented and the results are applied to the design of a corrugated waveguide wakefield accelerator.
 
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WEPB04 Design and Fabrication Challenges of Transition Section for the CWA Module 273
 
  • S.H. Lee, W.G. Jansma, S. Sorsher, K.J. Suthar, E. Trakhtenberg, G.J. Waldschmidt, A. Zholents
    ANL, Lemont, Illinois, USA
  • A.E. Siy
    UW-Madison/PD, Madison, Wisconsin, USA
 
  Funding: Work support by Laboratory Directed Research and Development funding from Argonne National Lab, by the Director, Office of Science, of the U.S. Department of Energy under contract DE-AC02-06CH11357.
An effort to build Argonne’s Sub-THz AcceleRator (A-STAR) for a future multiuser x-ray free-electron laser facility proposed in [1] is underway at Argonne National Laboratory. The A-STAR machine will utilize a compact collinear wakefield accelerator (CWA) assembled in modules. To extract the wakefield and monitor beam position downstream of each module, a 45-mm-long transition section (TS) has been proposed and designed. This paper will discuss the design and fabrication chal-lenges for production of the TS.
*A. Zholents et al., "A conceptual design of a Compact Wakefield Accelerator for a high repetition rate multi user Xray Free-Electron Laser Facility," in Proc. IPAC’18, Canada, 2018, pp. 1266-1268.
 
poster icon Poster WEPB04 [2.052 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2020-WEPB04  
About • paper received ※ 14 July 2021       paper accepted ※ 16 October 2021       issue date ※ 10 November 2021  
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WEPB05 Mechanical Design of a Compact Collinear Wakefield Accelerator 276
 
  • S.H. Lee, D.S. Doran, W.G. Jansma, S. Sorsher, K.J. Suthar, E. Trakhtenberg, G.J. Waldschmidt, A. Zholents
    ANL, Lemont, Illinois, USA
  • A.E. Siy
    UW-Madison/PD, Madison, Wisconsin, USA
 
  Funding: Work supported by Laboratory Directed Research and Development from Argonne National Lab, provided by the Director, Office of Science, of the U.S. Department of Energy under contract DE-AC02-06CH11357
Argonne National Laboratory is developing a Sub-THz AcceleRator (A-STAR) for a future multiuser x-ray free electron laser facility. The A-STAR machine will utilize a compact collinear wakefield accelerator (CWA) based on a miniature copper (Cu) corrugated waveguide as proposed*. The accelerator is designed to operate at a 20-kHz bunch repetition rate and will utilize the 180-GHz wakefield of a 10-nC electron drive bunch with a field gradient of 100 MVm’1 to accelerate a 0.3-nC electron witness bunch to 5 GeV. In this paper, we discuss specific challenges in the mechanical design of the CWA vacuum chamber module. The module consists of series of small quadrupole magnets with a high magnetic field gradient that houses a 2-mm diameter and 0.5-m-long corrugated tubing with brazed water-cooling channels and a transition section. The 45-mm-long transition section is used to extract the wakefield and to house a beam position monitor, a bellows assembly and a port to connect a vacuum pump. The CWA vacuum chamber module requires four to five brazing steps with filler metals of successively lower temperatures to maintain the integrity of previously brazed joints.
*A. Zholents et al., "A conceptual design of a Compact Wakefield Accelerator for a high repetition rate multi user Xray Free-Electron Laser Facility," in Proc. IPAC’18, Canada, 2018, pp. 1266~1268.
 
poster icon Poster WEPB05 [1.316 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2020-WEPB05  
About • paper received ※ 14 July 2021       paper accepted ※ 16 October 2021       issue date ※ 28 October 2021  
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THIO02 Determination of Maximum Repetition Rate of a Corrugated-Waveguide-Based Wakefield Accelerator 336
 
  • K.J. Suthar, S.H. Lee, S. Sorsher, E. Trakhtenberg, G.J. Waldschmidt, A. Zholents
    ANL, Lemont, Illinois, USA
  • A.E. Siy
    UW-Madison/PD, Madison, Wisconsin, USA
 
  Funding: This work supported by Laboratory Directed Research and Development (LDRD) funding from Argonne, provided by the Director, Office of Science, of the U.S. DOE under contract DE-AC02-06CH11357.
Thermal stresses generated due to the electromagnetic (EM) heating is a defining phenomenon in the mechanical design of the miniature copper-based corrugated wakefield accelerator (CWA). We investigate the effect of the EM heating due to the high repetition rate electron bunches traveling through a corrugated tube with 1-mm-inner-radius. The steady-state thermal analysis is coupled with computational fluid dynamics, and structural mechanics to determine the thermal effect on the operating conditions of CWA. It could carry a 10 nC drive bunch through the center of corrugated structure that generates a field gradient 100 Mv/m at 180 GHz, accelerating a trailing 0.3 nC witness bunch to 5 GeV. The wakefield produced by the traveling bunches can deposit about 600 W to 3000 W of energy on the inner wall of the device. Also, the instabilities in e-beam trajectories caused by thermal expansion, and the resulting stresses associated high-frequency repetition rate of 10 kHz to 50 kHz are the main concern for the waveguide. Tensile-yield failure due to moderate heating on the surface of the <200 micrometer wide trough regions of the corrugated tube may lead to arcing and loss of the wakefield.
 
slides icon Slides THIO02 [16.639 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-MEDSI2020-THIO02  
About • paper received ※ 21 July 2021       paper accepted ※ 06 October 2021       issue date ※ 27 October 2021  
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