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TY - CPAPER AU - Kubo, T. TI - Theoretical Field Limit and Cavity Surface Conditions: Nano-Scale Topography and Sub-millimeter Pit J2 - Proc. of International Conference on RF Superconductivity (SRF2015), Whistler, BC, Canada, Sept. 13-18, 2015 AB - The recent two theoretical papers*,** are briefly introduced. The former addresses the superheating field (Bs) suppression due to nano-defects distributing almost continuously on the cavity surface*. We introduce a model of the nano-defect. An analytical formula for Bs suppression factor is derived. By using the formula, suppression factors of bulk or multilayer superconductors and those after various surface processing technologies can be evaluated. An application to the dirty Nb processed by EP is also presented as an example. The latter address the magnetic field enhancement (MFE) at the sub-millimeter pit on the surface of cavity, which is thought to cause quench**. There exists the famous well-type pit model, but many of pits are not well-type but have gentle slopes. Impacts of the slope angle on MFE have not been well understood. We introduce a model that can describe a pit with an arbitrary slope angle. A formula to evaluate the MFE factor is derived. A pit with a gentle slope angle yields a much smaller MFE factor than the well-type pit. The formula can be applied to the calculation of MFE factors of real pits with arbitrary slope angles. PB - JACoW CY - Geneva, Switzerland SP - 86 EP - 89 KW - cavity KW - factory KW - simulation KW - radio-frequency KW - framework DA - 2015/12 PY - 2015 SN - 978-3-95450-178-6 DO - 10.18429/JACoW-SRF2015-MOPB008 UR - http://srf2015.vrws.de/papers/mopb008.pdf ER -