Development of vertical electropolishing process applied on 1300 and 704 MHz superconducting niobium resonators
Abstract
An advanced setup for vertical electropolishing of superconducting radio-frequency niobium elliptical cavities has been installed at CEA Saclay. Cavities are vertically electropolished with circulating standard HF-HF-H2SO4 electrolytes. Parameters such as voltage, cathode shape, acid flow, and temperature have been investigated. A low voltage (between 6 and 10 V depending on the cavity geometry), a high acid flow (25 L /min), and a low acid temperature (20° C) are considered as promising parameters. Such a recipe has been tested on single-cell and nine-cell International Linear Collider (ILC) as well as 704 MHz five-cell Super Proton Linac (SPL) cavities. Single-cell cavities showed similar performances at 1.6 K being either vertically or horizontally electropolished. The applied baking process provides similar benefit. An asymmetric removal is observed with faster removal in the upper half-cells. Multicell cavities (nine-cell ILC and five-cell SPL cavities) exhibit a standard Q0 value at low and medium accelerating fields though limited by power losses due to field emitted electrons.
- Publication:
-
Physical Review Accelerators and Beams
- Pub Date:
- August 2014
- DOI:
- 10.1103/PhysRevSTAB.17.083501
- Bibcode:
- 2014PhRvS..17h3501E
- Keywords:
-
- 74.70.Ad;
- 81.65.Ps;
- 82.47.Wx;
- 82.45.Qr;
- Metals;
- alloys and binary compounds;
- Polishing grinding surface finishing;
- Electrochemical engineering;
- Electrodeposition and electrodissolution