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DC Breakdown experiments for CLIC

For the production of the Compact Linear Collider (CLIC) RF accelerating structures, a material capable of sustaining high electric field, with a low breakdown rate and showing low damages after breakdowns is needed. A DC breakdown study is underway at CERN in order to test candidate materials and s...

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Detalles Bibliográficos
Autores principales: Descoeudres, A, Calatroni, S, Taborelli, M
Lenguaje:eng
Publicado: 2008
Materias:
Acceso en línea:http://cds.cern.ch/record/1151306
Descripción
Sumario:For the production of the Compact Linear Collider (CLIC) RF accelerating structures, a material capable of sustaining high electric field, with a low breakdown rate and showing low damages after breakdowns is needed. A DC breakdown study is underway at CERN in order to test candidate materials and surface preparations. The saturated breakdown fields of several metals and alloys have been measured, ranging from 100 MV/m for Al to 850 MV/m for stainless steel, being around 170 MV/m for Cu and 430 MV/m for Mo for example. The conditioning speed of Mo can be significantly improved by removing oxides at the surface with a vacuum heat treatment, typically at 875±C for 2 hours. DC breakdown rate measurements have been done with Cu and Mo electrodes, showing similar results as in RF experiments: the breakdown probability seems to exponentially increase with the applied field. Measurements of time delays before breakdown show two different populations of breakdowns, immediate and delayed breakdowns, indicating that two different mechanisms could exist. The repartition of these two populations depends on the electrodes material.