News & events
New year, new upgrades for JET | 27/01/2015
The JET machine area is a hive of activity as CCFE prepares the facility on behalf of EUROfusion for its next run of experiments later in 2015.
The shutdown period is an opportunity for engineers to tune up key systems on JET and to install new components to improve the tokamak's performance. This time round, the focus is on plasma fuelling and heating systems. The High Frequency Pellet Injector, which propels frozen deuterium fuel into the JET plasma, is being optimised and repositioned to achieve more reliable operation. A refurbished antenna – the Ion Cyclotron Resonance Heating system, which produces radiowaves that resonate with the plasma particles and heat them up – will also be plugged in. JET's antenna is similar to the one that the next-step ITER tokamak will use. Bringing it back online will mean that experiments can simulate ITER conditions more accurately, and has the added advantage of helping to flush out impurities from the core of the plasma.
European fusion researchers are keen to see how the 2014 JET tests have left their mark on the machine. The shutdown is enabling CCFE's team of remote handling engineers to remove sample tiles from the interior of JET so their condition can be analysed. Inspecting the tiles will yield valuable information about how the beryllium and tungsten wall lining is being affected by its close proximity to the plasma (another hot topic for ITER). And a remote-controlled vacuum cleaner has been inside JET collecting dust which can also give pointers on the interaction between the plasma and the wall materials.
In a similar vein, a new high-resolution camera has just been taken into the JET chamber to photograph the tiles in the ‘divertor' region. In this area, as the name suggests, impurities and waste material are diverted out of the plasma, and the tungsten surfaces of the divertor are exposed to intense heat as a result. The photographic survey is giving scientists the most detailed pictures yet of the condition of this area of the machine.
Guy Matthews, Head of CCFE's Plasma Operations & Boundary Physics Unit, explains: “With JET going to much higher power levels with deuterium-tritium operations in a couple of years, knowing how the tungsten-coated tiles are interacting with the plasma is essential. Overall we think they're performing well, but the images will tell us if any need replacing during the shutdown.”
The restart programme is set to begin in May, with the first plasma experiments scheduled for September.