Abstract
In-situ plasma processing is a promising technique to reduce field emission in superconducting radio-frequency cavities and thus maintain maximum accelerator performance for long-term operation. Continuous-wave accelerators such as FRIB are more challenging than pulsed accelerators due to relatively weak coupling (Qext = 2E6 to 1E7 for FRIB) via the fundamental power coupler (FPC). This results in an unfavorable mismatch at room temperature and makes fundamental-mode plasma processing difficult. Hence we have investigated the use of higher-order modes (HOMs) with less FPC mismatch. Several HOMs are promising for lower-mismatch plasma generation. However, HOMs often present a less favorable plasma distribution. To improve the plasma distribution, we are studying techniques to drive the plasma with two HOMs simultaneously. Plasma development results will be presented for FRIB β = 0.085 quarter wave resonators including ignition threshold measurements and plasma distribution assessments.
| Original language | English |
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| Title of host publication | Proceedings of the 32nd Linear Accelerator Conference, LINAC 2024 |
| Editors | Kelly Jaje |
| Publisher | JACoW Publishing |
| Pages | 348-351 |
| Number of pages | 4 |
| ISBN (Electronic) | 9783954502196 |
| DOIs | |
| State | Published - 2024 |
| Externally published | Yes |
| Event | 32nd Linear Accelerator Conference, LINAC 2024 - Chicago, United States Duration: Aug 25 2024 → Aug 30 2024 |
Publication series
| Name | Proceedings - Linear Accelerator Conference, LINAC |
|---|---|
| ISSN (Print) | 2226-0366 |
Conference
| Conference | 32nd Linear Accelerator Conference, LINAC 2024 |
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| Country/Territory | United States |
| City | Chicago |
| Period | 08/25/24 → 08/30/24 |
Funding
This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics and High Energy Physics and used resources of the FRIB Operations, which is a DOE Office of Science User Facility under Award Number DE-SC0023633 and DE-SC0018362. The MSU Accelerator Science and Engineering Trainee-ship program supported this study. The authors wish to thank the participants in our informal plasma processing collaboration with IJCLab, ANL, FNAL, and BNL, as well as the support from the FRIB processing and machining teams. We thank Zach Hosek, Sara Zeidan, and Jacob Brown for their helpful contributions to our plasma processing effort.