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Title: Large-Grain Superconducting Gun Cavity Testing Program Phase One Closing Report

This report details the experimental configuration and RF testing results for the first phase of a large-grained niobium electron gun cavity testing program being conducted in the Small Vertical Testing Facility in the Collider-Accelerator Department. This testing is meant to explore multi-pacting in the cavity and shed light on the behavior of a counterpart cavity of identical geometry installed in the Energy Recovery LINAC being constructed in the Collider-Accelerator Department at Brookhaven National Laboratory. This test found that the Q of the large-grained cavity at 4 K reached ~6.5 × 108 and at 2 K reached a value of ~6 × 109. Both of these values are about a factor of 10 lower than would be expected for this type of cavity given the calculated surface resistance and the estimated geometry factor for this half-cell cavity. In addition, the cavity reached a peak voltage of 0.6 MV before there was sig-nificant decline in the Q value and a substantial increase in field emission. This relatively low volt-age, coupled with the low Q and considerable field emission suggest contamination of the cavity interior, possibly during experimental assembly. The results may also suggest that additional chemical etching of the interior surface ofmore » the cavity may be beneficial. Throughout the course of testing, various challenges arose including slow helium transfer to the cryostat and cable difficulties. These difficulties and others were eventually resolved, and the re-port discusses the operating experience of the experiment thus far and the plans for future work aimed at exploring the nature of multipacting with a copper cathode inserted into the cavity.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
OSTI Identifier:
1116506
Report Number(s):
BNL--102610-2013-IR
R&D Project: KBCH139; KB0202011
DOE Contract Number:
AC02-98CH10886
Resource Type:
Technical Report
Research Org:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY