Croydon-based Centronic Ltd, a specialist in manufacture of electronic and electro-mechanical components for high performance applications, is supplying an Ultra High Vacuum electrical feed-through assembly for interfacing of the diagnostics related to the ITER-like Wall project, an EFDA/JET enhancement programme.

UHV electrical cable feed-through assembly

The ITER-like Wall project involves adding a considerable number of new diagnostic instruments to the JET Torus; for example, Langmuir probes (to measure the current density at the edge of the plasma) and thermocouples (to monitor the temperature of the first wall tiles). The UHV electrical feed-through acts as a vacuum chamber interface between the interior and exterior of the Torus.

Made from Inconel 600 and 316 stainless steel, the UHV feed-through assembly is 1.8m high and has a width of 0.8m at its widest point. It comprises a vacuum chamber with five feed-through cartridges, each capable of carrying 60 electrical signals, giving in total an assembly that will handle 300 conductors.

The 60 electrical conductors of each of the assembly's five feed-through cartridges comprise a mixture of three types of conductor: copper, chromel and alumel. The different conductor materials are required for interfacing of different diagnostic signals. These conductors have to be fed through the bulkheads on each feed-through cartridge and brazed in position using a complex brazing operation. “This is our biggest technical challenge on this project given the intricacy of the wiring” said Ian Emm, the Manufacturing Manager of Centronic Ltd. with responsibility for delivering this assembly. “Fortunately our manufacturing team has experience of this kind of work from similar, technically demanding, projects in other areas of the business.”

Ian Emm added, “This is a significant increase in capability compared to an earlier cable feed-through assembly supplied by Centronic to JET, which handled only 90 conductors, and when fully completed this larger assembly will weigh just over 300kg”. The size and weight of the assembly makes welding the main components in place, such as the flange plate and centre assemblies, an exacting task for the Centronic team. “The weight, the angle of the weld and the type of welding are all factors that have a bearing on the weld's complexity,” he noted.

The UHV electrical cable feed-through is scheduled for delivery later this year.

For more information on Centronic Ltd visit www.centronic.co.uk.