Week 13: Oops, a daisy in the vessel!

Added January 22nd, 2010 in Shutdown Weekly

A ‘daisy light’: The petals dissipate waste heat

During the first full week of work inside the JET torus, a full high-definition photographic survey has been completed. These photographs are will be used to record state of the carbon wall after nearly two years of plasma operation, before it is replaced by the new metallic tiles. A similar survey was carried out during the shutdown in 2007.

Having completed the survey, the Remote Handling team has started to install the equipment that will be needed for the rest of this year. The ‘in-vessel viewing system’ (IVVS) includes a set of dome cameras which can be remotely controlled to focus on specific areas where work will be carried out. It also includes a newly designed set of light-emitting diode (LED) lights, known as the ‘daisy lights’ due to their resemblance to the common flower of the same name. The petals are there to dissipate waste heat. Each of the four daisy lights draws 18 watts which is emitted by seven high performance LEDs.

Remote Handling have also started vacuum-cleaning the inside of the torus. Perhaps surprisingly, this is not just for ‘house-keeping’ purposes. Production of dust is an area of technology that is of great interest for future tokamak reactors. Therefore the dust collected this week will be studied in detail, along with some special marked tiles which allow the physicists to better understand the processes of erosion and deposition on the plasma facing components.

Background information
“Shutdown” in JET terms means to close the experiment down periodically to maintain and upgrade the fusion device. After this period experiments are going to be performed leading to better understanding of how to build and operate JET′s successor ITER. The current shutdown started on 26 October 2009. It is the fifth to be carried out remotely since commissioning JET in 1983. During the shutdown 86,000 components will be changed inside the JET torus.