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Title: Microwave power coupler for a superconducting multiple-cell cavity for accelerator application and its testing procedures

Abstract

Superconducting cavity resonators offer the advantage of high field intensity for a given input power, making them an attractive contender for particle accelerator applications. Power coupling into a superconducting cavity employed in a particle accelerator requires unique provisions to maintain high vacuum and cryogenic temperature on the cavity side, while operating with ambient conditions on the source side. Components introduced to fulfill mechanical requirements must show negligible obstruction of the propagation of the microwave with absence of critical locations that may give rise to electron multipaction, leading to a multiple section design, instead of an aperture, a probe, or a loop structure as found in conventional cavities. A coaxial power coupler for a superconducting multiple-cell cavity at 3.9 GHz has been developed. The cavity is intended to be employed as an accelerator to provide enhanced electron beam quality in a free-electron laser in Hamburg (FLASH) user facility. The design of the coupler called for two windows to sustain high vacuum in the cavity and two bellows to accommodate mechanical dimensional changes resulting from cryogenics. Suppression of multipacting was accomplished by the choice of conductor dimensions and materials with low second yield coefficients. Prior to integration with the cavity, the couplermore » was tested for intrinsic properties in a back-to-back configuration and conditioned for high-power operation with increasing power input. Maximum incident power was measured to be 61 kW. When integrated with the superconducting cavity, a loaded quality factor of 9 x 10 5 was measured by transient method. Coupler return loss and insertion loss were estimated to be around -21 dB and -0.2 dB, respectively.« less

Authors:
 [1]
  1. Illinois Inst. of Technology, Chicago, IL (United States)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
982477
Report Number(s):
FERMILAB-THESIS-2008-98
TRN: US1004290
DOE Contract Number:  
AC02-07CH11359
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCELERATORS; CAVITIES; CONFIGURATION; CRYOGENICS; DESIGN; DIMENSIONS; ELECTRON BEAMS; ELECTRONS; FREE ELECTRON LASERS; POWER INPUT; QUALITY FACTOR; SUPERCONDUCTING CAVITY RESONATORS; TESTING; TRANSIENTS; WINDOWS; Accelerators

Citation Formats

Li, Jianjian. Microwave power coupler for a superconducting multiple-cell cavity for accelerator application and its testing procedures. United States: N. p., 2008. Web. doi:10.2172/982477.
Li, Jianjian. Microwave power coupler for a superconducting multiple-cell cavity for accelerator application and its testing procedures. United States. https://doi.org/10.2172/982477
Li, Jianjian. Mon . "Microwave power coupler for a superconducting multiple-cell cavity for accelerator application and its testing procedures". United States. https://doi.org/10.2172/982477. https://www.osti.gov/servlets/purl/982477.
@article{osti_982477,
title = {Microwave power coupler for a superconducting multiple-cell cavity for accelerator application and its testing procedures},
author = {Li, Jianjian},
abstractNote = {Superconducting cavity resonators offer the advantage of high field intensity for a given input power, making them an attractive contender for particle accelerator applications. Power coupling into a superconducting cavity employed in a particle accelerator requires unique provisions to maintain high vacuum and cryogenic temperature on the cavity side, while operating with ambient conditions on the source side. Components introduced to fulfill mechanical requirements must show negligible obstruction of the propagation of the microwave with absence of critical locations that may give rise to electron multipaction, leading to a multiple section design, instead of an aperture, a probe, or a loop structure as found in conventional cavities. A coaxial power coupler for a superconducting multiple-cell cavity at 3.9 GHz has been developed. The cavity is intended to be employed as an accelerator to provide enhanced electron beam quality in a free-electron laser in Hamburg (FLASH) user facility. The design of the coupler called for two windows to sustain high vacuum in the cavity and two bellows to accommodate mechanical dimensional changes resulting from cryogenics. Suppression of multipacting was accomplished by the choice of conductor dimensions and materials with low second yield coefficients. Prior to integration with the cavity, the coupler was tested for intrinsic properties in a back-to-back configuration and conditioned for high-power operation with increasing power input. Maximum incident power was measured to be 61 kW. When integrated with the superconducting cavity, a loaded quality factor of 9 x 10 5 was measured by transient method. Coupler return loss and insertion loss were estimated to be around -21 dB and -0.2 dB, respectively.},
doi = {10.2172/982477},
url = {https://www.osti.gov/biblio/982477}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2008},
month = {12}
}

Thesis/Dissertation:
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