Posted on: 25th August 2011

Yesterday afternoon, the control room at the heart of JET was crowded and full of expectation. After an eighteen-month shutdown to upgrade the machine and four months of careful commissioning, the scientists were waiting so see the first plasma on the screen. The biggest part of this upgrade was to change the 4,500 tiles lining the vessel. The non-metal carbon was replaced by the metals beryllium and tungsten. The new materials are in accordance with the materials-mix chosen for JET’s successor, ITER. With its new ITER-like Wall, JET is the first fusion experiment to test the materials which will be used inside the next-generation international experiment.

The researchers expected to see just a flash of light as it often takes a few attempts to make the plasma following a shutdown. After the normal preliminary dry runs a beautiful plasma appeared on the screen. The first plasma with the new ITER-Like-Wall lasted an amazing 15 seconds. Peter Lomas, Head of Plasma Operations, explained: “We got plasma with no impurities and we got it on the first attempt. We were prepared to struggle, but we just did what we normally do with the old carbon wall. And that is the surprise.” Many sitting in the control room agreed that the plasma appeared on the screen as a “pink, poached salmon plasma”. Guy Matthews, Leader of the ITER-Like-Wall Project added: “Our first impression from spectroscopy is that the plasma was very clean. We got a really impressive result, given the large volume of new components.” Dragoslav Ciric, Restart Manager, observed: “The plasma just went on and on for about 15 seconds. It was beyond our expectations.”

EFDA Leader Francesco Romanelli commented: “Yesterday was a significant day for the worldwide fusion programme, with JET producing the first plasma with the new ITER-Like-Wall installed. We hadn’t expected that we would get such an excellent result immediately after commissioning. This very promising step has been accomplished but much more is on our agenda. I would like to congratulate all those who made all this possible.”