With the new ITER-Like-Wall in place, JET becomes something of a toddler who needs a lot of support taking its first steps. Scientists and engineers await the first experiments with both excitement and a little trepidation. Precautions have been taken in form of new diagnostics and re-organisations in the control room.

Acrowd is expected to gather in the JET control room when experiments start in August 2011. Everyone is eager to see the ITER-Like-Wall in action. Many of its tiles are made of beryllium, which is prone to melt under excessive heat loads. The scientists and engineers will have to proceed step-by-step, learning how the upgraded machine will react.

Preparing experiments.

Isabel Nunes, one of the Session Leaders at JET, is looking forward to the big day: “After having spent months on preparations, I am really eager to see things in action.” The Session Leader plays a central role in the experiments: They design the plasma pulses to achieve the experimental goals as defined by the Scientific Coordinator. This means setting the plasma parameters such as magnetic field, plasma current, or gas, planning the sequence of steps from the start through to the end of the pulse and defining the required heating power. Together with the Additional Heating Pilots, the Session Leader discusses the best strategy for when and how to apply the heating systems. The Diagnostic Coordinator requests all the diagnostics necessary for a planned experiment. During the experiment, they monitor the operation of the diagnostics to ensure the best quality of the experimental data. Elena de la Luna, one of JET’s Diagnostics Coordinators, can’t wait to get started: “We were really busy getting all diagnostics ready and calibrated. Now we are looking forward to the beginning of the experimental campaign.” Bearing ultimate responsibility for the machine, the Engineer in Charge has to approve all experimental plans.

Running JET is like playing with the best toy in the world.


In the control room.

To begin the experiment, the Power Supply Engineer starts JET’s two flywheel generators to build up power for the plasma pulse. The CODAS Duty Officers make sure that the computers and software are ready. A two and a half minute long countdown begins, urging all coordinators to ensure that their systems are ready. Once that is confirmed, the Engineer in Charge starts the pulse. “This really is the best part of my job” says Nick Balshaw, one of JET’s Engineers in Charge. It is fantastic when we get the machine running”. The Session Leader and Scientific Coordinator stand or sit in the front centre of the control room with the Engineer in Charge to their right. To their left, a new diagnostics unit has been set up: it comprises several cameras, whose measurements are used to create, in real time, a temperature map of the vessel. This information is integrated into the tokamak control system. If necessary, it will automatically adjust the plasma position and heating requests in order to avoid overheating the wall. To the left of the new unit is the area occupied by the Diagnostics Coordinators. With the new set-up, all team members can easily communicate in the event of unexpected occurrences. And, being a scientific experiment, new effects are bound to come up, often offering new, exciting insights into the physics of fusion plasmas.