Investigation of the dc vacuum breakdown mechanism
Breakdowns occurring in rf accelerating structures will limit the ultimate performance of future linear colliders such as the Compact Linear Collider (CLIC). Because of the similarity of many aspects of dc and rf breakdown, a dc breakdown study is underway at CERN to better understand the vacuum bre...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Physical Society
2009-09-01
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| Series: | Physical Review Special Topics. Accelerators and Beams |
| Online Access: | http://doi.org/10.1103/PhysRevSTAB.12.092001 |
| _version_ | 1819049074824839168 |
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| author | A. Descoeudres Y. Levinsen S. Calatroni M. Taborelli W. Wuensch |
| author_facet | A. Descoeudres Y. Levinsen S. Calatroni M. Taborelli W. Wuensch |
| author_sort | A. Descoeudres |
| collection | DOAJ |
| description | Breakdowns occurring in rf accelerating structures will limit the ultimate performance of future linear colliders such as the Compact Linear Collider (CLIC). Because of the similarity of many aspects of dc and rf breakdown, a dc breakdown study is underway at CERN to better understand the vacuum breakdown mechanism in a simple setup. Measurements of the field enhancement factor β show that the local breakdown field is constant and depends only on the electrode material. With copper electrodes, the local breakdown field is around 10.8 GV/m, independent of the gap distance. The β value characterizes the electrode surface state, and the next macroscopic breakdown field can be well predicted. In breakdown rate experiments, where a constant field is applied to the electrodes, clusters of consecutive breakdowns alternate with quiet periods. The occurrence and lengths of these clusters and quiet periods depend on the evolution of β. The application of a high field can even modify the electrode surface in the absence of breakdown. Measurements of time delays to breakdown show two distinct populations, immediate and delayed breakdowns, indicating that two different mechanisms could exist. The ratio of these two populations depends on the conditioning state of the electrodes and on material. Gas release during breakdown is dominated by H_{2} and CO. This degassing is mainly due to electron-stimulated desorption. During the quiet periods without breakdown, gases are also released but the quantities are much smaller. All the measurements presented here emphasize the crucial role of field emission in the breakdown triggering. |
| first_indexed | 2024-12-21T11:26:22Z |
| format | Article |
| id | doaj.art-6eddd226d579458db9891c94de60d328 |
| institution | Directory Open Access Journal |
| issn | 1098-4402 |
| language | English |
| last_indexed | 2024-12-21T11:26:22Z |
| publishDate | 2009-09-01 |
| publisher | American Physical Society |
| record_format | Article |
| series | Physical Review Special Topics. Accelerators and Beams |
| spelling | doaj.art-6eddd226d579458db9891c94de60d3282022-12-21T19:05:40ZengAmerican Physical SocietyPhysical Review Special Topics. Accelerators and Beams1098-44022009-09-0112909200110.1103/PhysRevSTAB.12.092001Investigation of the dc vacuum breakdown mechanismA. DescoeudresY. LevinsenS. CalatroniM. TaborelliW. WuenschBreakdowns occurring in rf accelerating structures will limit the ultimate performance of future linear colliders such as the Compact Linear Collider (CLIC). Because of the similarity of many aspects of dc and rf breakdown, a dc breakdown study is underway at CERN to better understand the vacuum breakdown mechanism in a simple setup. Measurements of the field enhancement factor β show that the local breakdown field is constant and depends only on the electrode material. With copper electrodes, the local breakdown field is around 10.8 GV/m, independent of the gap distance. The β value characterizes the electrode surface state, and the next macroscopic breakdown field can be well predicted. In breakdown rate experiments, where a constant field is applied to the electrodes, clusters of consecutive breakdowns alternate with quiet periods. The occurrence and lengths of these clusters and quiet periods depend on the evolution of β. The application of a high field can even modify the electrode surface in the absence of breakdown. Measurements of time delays to breakdown show two distinct populations, immediate and delayed breakdowns, indicating that two different mechanisms could exist. The ratio of these two populations depends on the conditioning state of the electrodes and on material. Gas release during breakdown is dominated by H_{2} and CO. This degassing is mainly due to electron-stimulated desorption. During the quiet periods without breakdown, gases are also released but the quantities are much smaller. All the measurements presented here emphasize the crucial role of field emission in the breakdown triggering.http://doi.org/10.1103/PhysRevSTAB.12.092001 |
| spellingShingle | A. Descoeudres Y. Levinsen S. Calatroni M. Taborelli W. Wuensch Investigation of the dc vacuum breakdown mechanism Physical Review Special Topics. Accelerators and Beams |
| title | Investigation of the dc vacuum breakdown mechanism |
| title_full | Investigation of the dc vacuum breakdown mechanism |
| title_fullStr | Investigation of the dc vacuum breakdown mechanism |
| title_full_unstemmed | Investigation of the dc vacuum breakdown mechanism |
| title_short | Investigation of the dc vacuum breakdown mechanism |
| title_sort | investigation of the dc vacuum breakdown mechanism |
| url | http://doi.org/10.1103/PhysRevSTAB.12.092001 |
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