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Latest Results of ILC High-Gradient R&D 9-cell Cavities at JLAB
Authors:
Rongli Geng
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| Abstract: It has been over a year since JLAB started processingand testing ILC 9-cell cavities in the frame work ofILC high-gradient cavity R&D, aiming at the goal of a35 MV/m gradient at a Qof 1E10 with a yield of 90%.The necessary cavity processing steps include field flatnesstuning, electropolishing (EP), hydrogen out-gassing undervacuum, high-pressure water rinsing, clean room assembly,and low temperature bake. These are followed by RFtest at 2 Kelvin. Ultrasonic cleaning with Micro-90, an effectivepost-EP rinsing recipe discovered at JLAB, is routinelyused. Seven industry manufactured 9-cell TESLAshapecavities are processed and tested repeatedly. So far,33 EP cycles are accumulated, corresponding to more than65 hours of active EP time. An emphasis put on RF testingis to discern cavity quench characteristics, including its natureand its location. Often times, the cavity performance islimited by thermal-magnetic quench instead of field emission.The quench field in some cavities is lower than 20MV/m and remains unchanged despite repeated EP, implyingmaterial and/or fabrication defects. The quench fieldin some other cavities is high but changes unpredictablyafter repeated EP, suggesting processing induced defects.Based on our experience and results, several areas are identifiedwhere improvement is needed to improve cavity performanceas well as yield. |
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| Publication Date: |
11 Feb 2008
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| Report numbers: |
JLAB-ACC-07-784; DOE/OR/23177-0305
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| DOE Contract number: |
AC05-06OR23177
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| Resource Type: |
Conference
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| Resource Relation: |
Conference: 13th Workshop on RF Superconductivity, Beijing, China, Oct. 14 - 19, 2007
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| Research Organizations: |
Thomas Jefferson National Accelerator Facility, Newport News, VA
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| Sponsoring Organizations: |
USDOE - Office of Science (SC)
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| Country of Publication: |
United States
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| Language: |
English
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