Paper | Title | Page |
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MOPB036 | TOF-SIMS Study of Nitrogen Doping Niobium Samples | 169 |
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Nitrogen doping treatment with the subsequent electropolishing (EP) of the niobium superconducting cavity can significantly increase the cavity’s quality factor up to a factor of 3. The nitrogen doping experiment has been successfully repeated and demonstrated. But the mechanism of the nitrogen doping effect remains unclear. Nitrogen doping study on niobium samples was carried out in Peking University. The niobium samples were manual processed to avoid heat generation. The experiment condition is close to that of the Fermilab. After the nitrogen doping treatment, the samples were mildly electropolished with the thickness of 1.3μm, 1.9μm, 3.3μm, 4.2μm, 5.1μm, 5.9μm and 7.0μm. The time of flight secondary ion mass spectrometry (TOF-SIMS) measurements show that the samples directly after nitrogen doping have a much higher nitrogen concentration in the depth of about 90nm. When the EP removal is larger than 1.3μm, the samples’ impurity elements is remarkably reduced and their distribution is similar to each other. Also the measured results to some extent prove that EP removal can introduce H to the niobium surface. | ||
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THPB079 | Improved Capacitive Coupling Type RF Power Couplers for a Cryomodule With Two 9-Cell Cavities | 1313 |
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Funding: Work supported by Major State Basic Research Development Program of China(Grant No. 2011CB808302 and 2011CB808304) A capacitive coupling RF power coupler was used for the DC-SRF photoinjector at Peking University. Recently, improved capacitive coupling power couplers, which will be used for a new cryomodule with two 9-cell cavities have been designed and fabricated. The main modifications include enlarging the supporting rods of inner conductors in order to increase heat conduction, moving the bellows from the quarter-wave transformer to the 50 Ω coaxial line to avoid the mismatch during Qext adjusting. Two modified power coupler have already finished RF conditioning up to 10kW, TW, duty factor 30%. In this paper, detailed design based on multi-physics analysis and the conditioning of this improved capacitive coupling RF Power coupler will be presented. |
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FRAA05 | A 1.3 GHz Cryomodule with 2x9-Cell Cavity for SETF at Peking University | 1443 |
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Funding: Work supported by National Basic Research Project (No. 2011CB808304 and 2011CB808302)and NDRC project. The straight beam line of SETF at Peking University is under construction, which consists of a DC-SRF photoinjector and a superconducting linac with two 9-cell cavities. Stable operation of the DC-SRF photoinjector has been realized and the design, manufacture and assembly of the cryomodule with two 9-cell cavities have been completed. Improved capacitive coupling RF power coupler and fast tuner with piezo are adopted |
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Slides FRAA05 [3.709 MB] | |
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