Magneto-thermal limitations in superconducting cavities at high radio-frequency fields
The performance of superconducting radio-frequency Nb cavities at high radio-frequency (rf) fields in the absence of field emission can be limited by either a sharp decrease of the quality factor Q0(Bp) above peak surface magnetic fields Bp ∼100 mT or by a quench. We have measured Q0(Bp) at 2 K of s...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Frontiers Media S.A.
2024-03-01
|
| Series: | Frontiers in Electronic Materials |
| Subjects: | |
| Online Access: | https://www.frontiersin.org/articles/10.3389/femat.2024.1339293/full |
| _version_ | 1797269075637829632 |
|---|---|
| author | I. Parajuli G. Ciovati G. Ciovati A. Gurevich |
| author_facet | I. Parajuli G. Ciovati G. Ciovati A. Gurevich |
| author_sort | I. Parajuli |
| collection | DOAJ |
| description | The performance of superconducting radio-frequency Nb cavities at high radio-frequency (rf) fields in the absence of field emission can be limited by either a sharp decrease of the quality factor Q0(Bp) above peak surface magnetic fields Bp ∼100 mT or by a quench. We have measured Q0(Bp) at 2 K of several 1.3 GHz single-cell Nb cavities with different grain sizes, and with different ambient magnetic fields and cooldown rates below the critical temperature. Temperature mapping and a novel magnetic field mapping systems were used to find the location of “hot-spots” and regions of trapped magnetic flux. The use of a variable input coupler allowed further exploring the dissipative state. The results showed a remarkable thermal stability in some cavities with up to 200 W of rf power dissipation at 2 K, whereas other cavities quenched at much lower rf power. We observed a narrow distributions of the onset fields of hot-spots which were not affected by thermal cycling or by conditions which favor the formation of Nb hydrides. Furthermore, a poor correlation was found between the location of hot-spots and trapped vortices. We suggest that the totality of our experimental data can be explained by a sharp increase of the residual surface resistance above 120–140 mT due to the field-induced breakdown of a proximity-coupled metallic suboxide layer at the surface. |
| first_indexed | 2024-04-25T01:42:37Z |
| format | Article |
| id | doaj.art-e1f80ac55fbf4b5fb5e09d28e1dc2b4c |
| institution | Directory Open Access Journal |
| issn | 2673-9895 |
| language | English |
| last_indexed | 2024-04-25T01:42:37Z |
| publishDate | 2024-03-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Electronic Materials |
| spelling | doaj.art-e1f80ac55fbf4b5fb5e09d28e1dc2b4c2024-03-08T04:43:03ZengFrontiers Media S.A.Frontiers in Electronic Materials2673-98952024-03-01410.3389/femat.2024.13392931339293Magneto-thermal limitations in superconducting cavities at high radio-frequency fieldsI. Parajuli0G. Ciovati1G. Ciovati2A. Gurevich3Center for Accelerator Science, Department of Physics, Old Dominion University, Norfolk, VA, United StatesCenter for Accelerator Science, Department of Physics, Old Dominion University, Norfolk, VA, United StatesThomas Jefferson National Accelerator Facility, Newport News, VA, United StatesCenter for Accelerator Science, Department of Physics, Old Dominion University, Norfolk, VA, United StatesThe performance of superconducting radio-frequency Nb cavities at high radio-frequency (rf) fields in the absence of field emission can be limited by either a sharp decrease of the quality factor Q0(Bp) above peak surface magnetic fields Bp ∼100 mT or by a quench. We have measured Q0(Bp) at 2 K of several 1.3 GHz single-cell Nb cavities with different grain sizes, and with different ambient magnetic fields and cooldown rates below the critical temperature. Temperature mapping and a novel magnetic field mapping systems were used to find the location of “hot-spots” and regions of trapped magnetic flux. The use of a variable input coupler allowed further exploring the dissipative state. The results showed a remarkable thermal stability in some cavities with up to 200 W of rf power dissipation at 2 K, whereas other cavities quenched at much lower rf power. We observed a narrow distributions of the onset fields of hot-spots which were not affected by thermal cycling or by conditions which favor the formation of Nb hydrides. Furthermore, a poor correlation was found between the location of hot-spots and trapped vortices. We suggest that the totality of our experimental data can be explained by a sharp increase of the residual surface resistance above 120–140 mT due to the field-induced breakdown of a proximity-coupled metallic suboxide layer at the surface.https://www.frontiersin.org/articles/10.3389/femat.2024.1339293/fullradiofrequencyniobiumsuperconducting RF cavitiesparticle acceleratorssurface resistance (Rs)nonlinear rf losses |
| spellingShingle | I. Parajuli G. Ciovati G. Ciovati A. Gurevich Magneto-thermal limitations in superconducting cavities at high radio-frequency fields Frontiers in Electronic Materials radiofrequency niobium superconducting RF cavities particle accelerators surface resistance (Rs) nonlinear rf losses |
| title | Magneto-thermal limitations in superconducting cavities at high radio-frequency fields |
| title_full | Magneto-thermal limitations in superconducting cavities at high radio-frequency fields |
| title_fullStr | Magneto-thermal limitations in superconducting cavities at high radio-frequency fields |
| title_full_unstemmed | Magneto-thermal limitations in superconducting cavities at high radio-frequency fields |
| title_short | Magneto-thermal limitations in superconducting cavities at high radio-frequency fields |
| title_sort | magneto thermal limitations in superconducting cavities at high radio frequency fields |
| topic | radiofrequency niobium superconducting RF cavities particle accelerators surface resistance (Rs) nonlinear rf losses |
| url | https://www.frontiersin.org/articles/10.3389/femat.2024.1339293/full |
| work_keys_str_mv | AT iparajuli magnetothermallimitationsinsuperconductingcavitiesathighradiofrequencyfields AT gciovati magnetothermallimitationsinsuperconductingcavitiesathighradiofrequencyfields AT gciovati magnetothermallimitationsinsuperconductingcavitiesathighradiofrequencyfields AT agurevich magnetothermallimitationsinsuperconductingcavitiesathighradiofrequencyfields |