Author: Geng, R.L.
Paper Title Page
WEPMR033 Observation of Stable Low Surface Resistance in Large-Grain Niobium SRF Cavities 2344
 
  • R.L. Geng
    JLab, Newport News, Virginia, USA
  • S.C. Huang
    IMP/CAS, Lanzhou, People's Republic of China
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Low surface resistance, or high unloaded quality factor (Q0), superconducting radio frequency (SRF) cavities are being pursued actively nowadays as their application in large-scale CW SRF accelerators can save capital and operational cost in cryogenics. There are different options in realization of such cavities. One of them is the large-grain (LG) niobium cavity. In this contribution, we present new experimental results in evaluation of LG niobium cavities cooled down in the presence of an external magnetic field. High Q0 values are achieved even with an ambient magnetic field of up to 100 mG. More over, it is observed that these high Q0 values are super-robust against repeated quench, literally not affected at all after the cavity being deliberately quenched for hundreds of times in the presence of an ambient magnetic field of up to 200 mG.
 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR033  
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THOBB03 Root Causes of Field Emitters in SRF Cavities Placed in CEBAF Tunnel 3198
 
  • R.L. Geng
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
It has been suspected that appearance of new field emitters can occur in SRF cavities after their placement in accelerator tunnel for long term beam operation. This apparently has been the case for CEBAF. However, no physical evidence has been shown in the past. In this contribution, we will report on the recent results concerning the root cause of field emitters in SRF cavities placed in CEBAF tunnel. We will discuss these results in the context of high-reliability and low-cryogenic-loss operation of CEBAF.
 
slides icon Slides THOBB03 [3.768 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOBB03  
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