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Title: Investigation of differential surface removal due to electropolishing at JLab

Surface chemistry carried out for Superconducting Radio Frequency (SRF) cavities such as Buffered Chemical Polishing (BCP) and Electropolishing (EP) aims to uniformly remove the internal surface of a cavity along the entire structure and within each cell from equator to iris in order to obtain an equally etched surface. A uniform removal, however, is not readily achievable due to the complex fluid flow and varying temperatures of the acid mixture, which can lead to differential etching. This needs to be considered when envisaging a certain surface damage removal throughout the interior. The process-specific differential etching influences the target frequency set at the manufacturing stage as well as the field flatness and length of the as-built cavity. We report on analyses of JLab's present EP system using experimental data for six nine-cell cavities that have been processed recently in the frame of the LCLS-II high-Q development plan. In conjunction with numerical simulations, the differential etching and the impact on field flatness is assessed.
Authors:
 [1] ;  [1] ;  [1]
  1. Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Publication Date:
OSTI Identifier:
1223453
Report Number(s):
JLAB-ACC--15-2070; DOE/OR/23177--3434
TRN: US1601429
DOE Contract Number:
AC05-06OR23177
Resource Type:
Conference
Resource Relation:
Conference: IPAC 2015, Richmond, VA (United States), 3-8 May 2015
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; CEBAF ACCELERATOR; ELECTROPOLISHING; ETCHING; EXPERIMENTAL DATA; SUPERCONDUCTING CAVITY RESONATORS; COMPUTERIZED SIMULATION; LENGTH; ELECTROMAGNETIC FIELDS; MANUFACTURING