| Autor: |
I. Parajuli, G. Ciovati, A. Gurevich |
| Jazyk: |
angličtina |
| Rok vydání: |
2024 |
| Předmět: |
|
| Zdroj: |
Frontiers in Electronic Materials, Vol 4 (2024) |
| Druh dokumentu: |
article |
| ISSN: |
2673-9895 |
| DOI: |
10.3389/femat.2024.1339293 |
| Popis: |
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. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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