It is a complete change to the device”, says Jérôme Bucalossi. The project leader of WEST, the only tokamak in EUROfusion’s programme to specifically test plas ma facing components (PFC), is excited: a lot of work has been done to ensure that the Tungsten (or Wolfram in German) Environ ment in Steady-state Tokamak matches the requirements of the European fusion research.

After a complete make-over of WEST, the former Tore Supra tokamak, which is housed at the French research centre CEA in Cadarache, is expected to produce its first plasma at the end of 2016. “The trickiest thing was to install the infrared thermography systems. These observe the temperature of the plasma facing components during fusion experiments. The challenge was to integrate the system properly into the existing vessel”, explains Bucalossi.

Surface inspection: The Articulated Inspection Arms twists like a snake through the vessel. (Images: Christophe Roux)

Surface inspection: The Articulated Inspection Arms twists like a snake through the vessel. (Images: Christophe Roux)

Detect overheating of materials in fusion experiments

“There is a lot to cover and the footage must be in very high resolution, so that we can detect whether the components are overheating or if there are any other problems”, he adds. To inspect the vessel sufficiently, WEST uses a so called “Articulated Inspection Arm”. Like a snake with a camera as its head it enters through a 20 cm flange and winds along points in the vessel which are usually difficult to access. This allows to precisely monitor the vessel wall between fusion experiments without breaking the vacuum.

60 diagnostics to be characterised

WEST has integrated a total of 60 diagnostics including visible spectroscopy designed to monitor tungsten erosion. It was also challenging to ensure the accurate integration of new diagnostics in the reduced available volume while minimising the modification of existing diagnostics. Now, each of the diagnostics systems can be removed without affecting the others. With its special capability to test actively cooled PFCs in long lasting plasma, WEST complements the existing EUROfusion facilities by combining ITER divertor high heat flux technology and tokamak operation.

The campaign for EUROfusion which is planned for late November 2016, will investigate power load and the power deposition profile from the new divertor. A call for participation in the WEST campaign is currently being prepared and will be communicated before the end of this year. The experiments will mainly serve Mission 2 of the European fusion road map: Heat-exhaust systems.