DocumentCode :
3197396
Title :
SRF Performance of CEBAF After Thermal Cycle to Ambient Temperature
Author :
Rimmer, R.A. ; Benesch, J. ; Preble, J. ; Reece, C.
Author_Institution :
JLab, Newport News, VA 23606, USA
fYear :
2005
fDate :
16-20 May 2005
Firstpage :
665
Lastpage :
667
Abstract :
In September 2003, in the wake of Hurricane Isabel, JLab was without power for four days after a tree fell on the main power lines feeding the site. This was long enough to lose insulating vacuum in the cryomodules and cryogenic systems resulting in the whole accelerator warming up and the total loss of the liquid helium inventory. This thermal cycle stressed many of the cryomodule components causing several cavities to become inoperable due to helium to vacuum leaks. At the same time the thermal cycle released years of adsorbed gas from the cold surfaces. Over the next days and weeks this gas was pumped away, the insulating vacuum was restored and the machine was cooled back down and recommissioned. In a testament to the robustness of SRF technology, only a small loss in energy capability was apparent, although individual cavities had quite different field-emission characteristics compared to before the event. In Summer 2004 a section of the machine was again cycled to room temperature during the long maintenance shutdown. We report on the overall SRF performance of the machine after these major disturbances and on efforts to characterize and optimize the new behavior for high-energy running.
Keywords :
Cryogenics; Dielectric liquids; Gas insulation; Helium; Hurricanes; Pumps; Temperature; Thermal stresses; Trees - insulation; Vacuum systems;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the
Print_ISBN :
0-7803-8859-3
Type :
conf
DOI :
10.1109/PAC.2005.1590521
Filename :
1590521
Link To Document :
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