| Microscopic examination of defects located by thermometry in 1.5 GHz superconducting niobium cavities (2007) | |||||||||||||
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| A new high resolution, high speed thermometry system has been built at Cornell to permit the study of anomalous loss regions in 1.5 GHz superconducting Nb cavities in superfluid He. Following a cavity test, the cavity is dissected for examination of these regions in an electron microscope. Presented is a survey of the topographical and elemental characteristics of various defects found so far. Included are field emitters which were known to be active at the end of a cavity test, as well as those which processed. I. INTRODUCTION In present day Nb cavities the surface magnetic fields achieved still fall far short of those theoretically attainable. The maximum field possible is believed to be the superheating rf field (2300 Oe @ 1.6 K) [1]. In practice, though, one finds that the cavity Quality (Q) already begins to drop between 300 and 1000 Oe. Several mechanisms responsible for anomalous power dissipation at these fields have been identified. Presently, the most common ones are diele... | |||||||||||||
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