Subscribe options

Select your newsletters:

Please enter your email address:

@

Your email address will only be used for the purpose of sending you the ITER Organization publication(s) that you have requested. ITER Organization will not transfer your email address or other personal data to any other party or use it for commercial purposes.

If you change your mind, you can easily unsubscribe by clicking the unsubscribe option at the bottom of an email you've received from ITER Organization.

For more information, see our Privacy policy.

News & Media

Latest ITER Newsline

  • Image of the Week | Sector 5 is on its way

    The first vacuum vessel sector produced in Europe travelled last week between Monfalcone, Italy, and the French port of Fos-sur-Mer. The 440-tonne component had [...]

    Read more

  • Anniversary | ITER Document Management system turns 20

    Whatever its nature, every large project generates huge numbers of documents. And when project collaborators operate from different countries, as was the case f [...]

    Read more

  • Fusion world | Latvia mints a fusion-themed coin

    Last week, ITER Plant Installation Program Manager Bertrand Roques brought back a small but highly symbolic contribution to the ITER budget from a colloqui [...]

    Read more

  • Outreach | Train traveller? Meet ITER

    Anyone arriving at or leaving from the Aix-en-Provence high-speed train station this month is liable to learn a little about the ITER project, as there is hardl [...]

    Read more

  • Fusion world | Innovative approaches and how ITER can help

    More than 30 private fusion companies from around the world attended ITER's inaugural Private Sector Fusion Workshop in May 2024. Four of them participated in a [...]

    Read more

Of Interest

See archived entries

ITER NEWSLINE -

Thermal shields panels

All that glitters is not silver

The ITER superconducting magnets, which operate at the ultra-cold temperature of 4 K (minus 269 °C), must be protected from any type of heat transfer. Several components contribute to the magnetic system's thermal insulation: the vacuum in the cryostat ensures that no heat is transferred by convection, the structures that support the vertical coils (gravity supports) greatly reduce conduction by contact, and the thermal shield system raises an obstacle against the radiative heat transfer (electromagnetic waves) generated by sources of heat.

When silver-coated, a thermal shield panel looked like a jewel. Now polished to perfection (less than 80 microns rugosity) it looks like a mirror. (Click to view larger version...)
When silver-coated, a thermal shield panel looked like a jewel. Now polished to perfection (less than 80 microns rugosity) it looks like a mirror.
One of the most efficient ways of blocking thermal radiation is to coat thermal shield panels with a thin layer of pure silver, a "low-emissivity" element. However during early machine assembly, it was discovered that the processes involved in silver-coating operations and thermal shield cooling pipe welding had in some cases resulted in the presence of chlorine residues and associated corrosion, with millimetre-deep cracks.

Two sets of vacuum vessel thermal shield panels were sent to India (soon to be followed by 5 others) for repair. Repair entailed removing all cooling pipes, grinding to remove up to approximately ~2mm of base material just under the cooling pipes, and finally re-attaching new pipes.

In terms of thermal emissivity, ultra-high polishing ensures a similar performance to silver coating. (Click to view larger version...)
In terms of thermal emissivity, ultra-high polishing ensures a similar performance to silver coating.
One set has already been shipped back to ITER where its silver coating was removed and its surface polished to mirror-like perfection (less than 80 microns rugosity). In terms of thermal emissivity ultra-high polishing ensures a similar performance as silver coating.

The outboard panel pictured here in the former Cryostat Workshop will soon join the two other elements of the thermal shield set for vacuum vessel sector #7 already in place in the handling tool in the Assembly Hall.

return to the latest published articles