Vertical electropolishing cabinet
Vertical electropolishing cabinet

Vertical electropolishing station


Chemical and electrochemical treatment of elliptical cavities (maximum cavity height: 1.8 m and maximum mass: 200 kg).

This station allows one to perform chemical or electrochemical polishing of the internal surface of niobium cavities.


Technical means

  • Power supply: 20 V, 1200 A,
  • Acid flow rate: 40 l / min,
  • 300 l acid tank,
  • Pipe and pumps made of PFA material, teflon coating of the acid tank,
  • Cavities are handled by a crane with specific tooling for each cavity. The station is also equipped with a table for horizontally inserting the cathodes,
  • Use of rotating cathode for uniform material removal,
  • External cooling of the cavity with water sprays,
  • Online measurement of the cavity thickness during treatment.

Electropolishing cycles are automated.

The station is located in a Non-Explosive Atmosphere Area. Measures are taken to limit the various sources of risk:

  • Hydrogen detection via 2 detectors with automated shut-off of the generator and ventilation of the treatment booth which ensures a low concentration of process gases in the event of a leak,
  • Control of the acid temperature (via an 18 kW power cooling unit connected to a heat exchanger: 156 m PFA pipe) to minimize the risks associated with exothermic reactions (the working temperature is below 20 °).

Additional facilities: acid storage room, gas extractor-washer which ensures the ventilation of workstations, acid liquid waste collection and treatment system, pure and ultrapure water treatment plant (resistivity : 17.7-17.9 MΩ.cm).

Vertical electropolishing cabinet

Vertical electropolishing cabinet

Achievements, related projects

  • Treatment performed to increase the surface quality of superconducting cavities, in the framework of the XFEL, ESS and ILC projects,
  • R&D experiments on vertical electropolishing,
  • Preparation for other R&D related activities: doping, multilayer, coating.

Technical steps, expertise

  • Vertical positioning of the cavity,           
  • Chemical or electrochemical treatment (automated cycle),
  • Rinsing with ultrapure water (resistivity: 17.9 MΩ.cm) and extraction of acids and polluted water.


#3950 - Last update : 09/23 2022


Retour en haut