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Title: Cryogenic rf test of the first SRF cavity etched in an rf Ar/Cl2 plasma

Journal Article · · AIP Advances
DOI:https://doi.org/10.1063/1.4991888· OSTI ID:1641619
 [1];  [2];  [1];  [2];  [1];  [2];  [1]
  1. Old Dominion Univ., Norfolk, VA (United States)
  2. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
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An apparatus and a method for etching of the inner surfaces of superconducting radio frequency (SRF) accelerator cavities are described. The apparatus is based on the reactive ion etching performed in an Ar/Cl2 cylindrical capacitive discharge with reversed asymmetry. To test the effect of the plasma etching on the cavity rf performance, a 1497 MHz single cell SRF cavity was used. The single cell cavity was mechanically polished and buffer chemically etched and then rf tested at cryogenic temperatures to provide a baseline characterization. The cavity’s inner wall was then exposed to the capacitive discharge in a mixture of Argon and Chlorine. The inner wall acted as the grounded electrode, while kept at elevated temperature. The processing was accomplished by axially moving the dc-biased, corrugated inner electrode and the gas flow inlet in a step-wise manner to establish a sequence of longitudinally segmented discharges. The cavity was then tested in a standard vertical test stand at cryogenic temperatures. The rf tests and surface condition results, including the electron field emission elimination, are presented.

Research Organization:
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Nuclear Physics (NP); USDOE Office of Science (SC), High Energy Physics (HEP)
Grant/Contract Number:
SC0014397; AC05-06OR23177
OSTI ID:
1641619
Alternate ID(s):
OSTI ID: 1414016
Report Number(s):
JLAB-ACC-16-2299; DOE/OR/23177-3878; arXiv:1605.06494; TRN: US2201868
Journal Information:
AIP Advances, Vol. 7, Issue 12; ISSN 2158-3226
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 3 works
Citation information provided by
Web of Science

References (10)

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journal May 2016
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Cited By (2)

Effect of self-bias on cylindrical capacitive discharge for processing of inner walls of tubular structures—Case of SRF cavities journal August 2018
Argon metastable and resonant level densities in Ar and Ar/Cl2 discharges used for the processing of bulk niobium journal September 2019

Figures / Tables (3)

FIG. 1(p. 3)figure FIG. 1
FIG. 2(p. 4)figure FIG. 2
FIG. 3(p. 5)figure FIG. 3

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70 PLASMA PHYSICS AND FUSION TECHNOLOGY
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Surface collisions
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Transition metals