JET's salient features

Interior of JET with its new ITER-like wall of tungsten and beryllium; credit: UKAEA

At the core of JET is the vacuum vessel where the fusion plasma is confined by means of strong magnetic fields and plasma currents (up to 4 tesla and 5 mega amperes). In the current configuration the major and minor radii of the plasma torus are 3 metres and 0.9 metres respectively, and the total plasma volume is 90 cubic metres. A divertor at the bottom of the vacuum vessel allows escaping heat and gas to be exhausted in a controlled way. Since 2011 the first wall of the vacuum vessel has been made of beryllium and tungsten, mirroring the material choices of ITER.

Some other salient features of JET include the following:

  • A flexible and powerful plasma auxiliary heating system, consisting of Neutral Beam Injection (34 megawatts), Ion Cyclotron Resonance Heating (10 megawatts)
  • An extensive diagnostic suite of around 100 individual instruments capturing up to 18 gigabytes of raw data per plasma pulse.
  • A high frequency pellet injector for plasma refuelling and for ELM pacing studies.
  • A massive gas injection valve, and a shattered pellet injector for plasma disruption studies.
  • Capabilities to operate with tritium fuel – unique among today’s fusion devices.
  • Beryllium handling facilities, allowing use of beryllium plasma-facing components.
  • Remote handling facilities that allow advanced engineering work to be performed inside the vacuum vessel without the need for manned access.
  • Real-Time control systems used for both protection against harmful events and control of the external actuators for designing and maintaining a pulse around desired parameter.