A 283 million euro operation contract signed between the European Commission and the Culham Centre for Fusion Energy (CCFE) in July secures JET operation until 2018. The contract represents the largest in the history of JET with an unprecedented duration of five years. After finishing the current campaign, preparations will start for experiments with deuterium-tritium plasmas.

Up to mid-October, experiments on JET exploit the ITER-Like Wall with increased heating power (up 34 Megawatt (MW) of Neutral Beam Heating and 5-6 MW of Ion Cyclotron Resonance Heating, ICRH), hence creating plasma scenarios similar to those in ITER. Experiments focus on developing plasma scenarios and on studying disruption mitigation and runaway electrons (Ed. note: Disruptions are potentially harmful events during which a plasma very rapidly loses its power. Runaway electrons are strong, potentially harmful electron beams that may develop during disruptions). Also, studies of energy and particle transport in the plasma and of reducing the heat stress at the vessel wall by seeding impurities into certain plasma areas are carried out. “The campaign is running pretty well, operators and task forces are working very hard, even on weekends. Even though we are operating through the summer holidays, we have been able to man all experiments with scientists,” says Lorne Horton, Head of JET Exploitation. The campaigns will end with a series of experiments in hydrogen, as JET intends to use the ITER-Like Wall to test all working gases planned for ITER: hydrogen, helium, deuterium and deuterium-tritium. Comparisons between hydrogen and deuterium operation will also help prepare for the JET deuterium-tritium and tritium experiments. In autumn JET will be shutdown until April 2015. Wall tiles will be removed to evaluate the tungsten melt experiments carried out for ITER and to continue analysing how tungsten debris is deposited and re-deposited on the reactor wall. The upgraded ITER-Like ICRH antenna and an optimised pellet injector will also be installed.

That the new operating contract runs for five years instead of the usual one-year renewable contracts is a big step forwards. It makes the preparation and planning for deuterium-tritium operation in 2017 much easier.

Lorne Horton, Head of the JET Exploitation Unit

Deuterium-Tritium Experiments

The current plans for JET foresee a scientific campaign with deuterium-tritium (D-T) plasmas in 2017. D-T plasmas produce more fusion power and will therefore be the fuel for fusion power plants. ITER will carry out its ultimate experiments with D-T plasmas. Usually fusion laboratories operate with D-D plasmas, thus avoiding handling the radioactive tritium. D-D experiments can be scaled up to predict the performance of D-T plasmas. JET is the only device operating that has been licensed for tritium. During its last high power D-T campaign in 1997, it produced a world record amount of fusion power. Since then, JET has become a much more ITER-like machine: Its vessel wall comprises the same materials as ITER and its upgraded heating systems allow it to operate with similar plasma scenarios as ITER. “When JET did the last D-T campaign in 1997, we did not have the hybrid scenario which will be used in ITER, but we do have it now. Back then, we also did not have the ITER-like plasma facing components made of tungsten and beryllium. That makes the D-T experiments very challenging and interesting with respect to physics, technology and operation,” explains Xavier Litaudon, Head of the EUROfusion ITER Physics Department. The JET Exploitation Unit and CCFE have a long to-do-list before the campaign starts: apart from implementing the refurbished ICRH Antenna and the pellet injector, all components must be commissioned for operating with the more powerful D-T plasmas, staff must be trained, the safety measures must be checked, diagnostic systems must be tested and possibly adjusted for operation with tritium plasmas and finally, the necessary level of plasma performance must be ensured.

The fact that we can now rely on a five year contract makes it easier for us and CCFE to fulfil the goal defined by the Fusion Roadmap.

Tony Donné, EUROfusion Programme Manager

Organisational Changes

The way JET is managed within the European Fusion Programme has been reorganised with the implementation of the EUROfusion consortium. Historically, Europe managed its plasma physics research for ITER (“ITER Physics”) and JET research and operation (“JET Department”) separately. Operation of the JET facilities is provided as an in-kind contribution to the consortium via a contract between the European Commission and the Culham Centre for Fusion Energy. The JET Exploitation Manager, Lorne Horton, assisted by the JET Exploitation Unit, is responsible for implementing the JET operation contract on behalf of the Commission, including overseeing JET operation and ensuring consistency with the Fusion Roadmap. The split between operational tasks and the organisation of scientific work on JET has opened the window for the combination of ITER Physics and JET scientific activities within one department. Head of this
combined ITER Physics Department is Xavier Litaudon. Given the large similarities between JET and ITER Physics, this change is a strong organisational improvement which will enable EUROfusion to work more efficiently. “In fact, I applied for my position because I felt that in order to best prepare for ITER we must combine JET and ITER Physics. The new set-up enables us to design one consistent research programme within which all European Task Forces and Project Leaders collaborate closely in the common goal, ensuring the success of ITER,” explains Xavier Litaudon.

It is important that we prepare ITER operational scenarios on JET with deuterium-tritium experiments under ITER-relevant conditions with respect to physics and operation.

Xavier Litaudon, Head of the EUROfusion ITER Physics Department

An ongoing activity driven by the EU Commission and by EUROfusion is to open up JET beyond Europe. A review conducted by a panel of external experts, the so-called “Wagner-Panel”, advised that JET should involve the other ITER parties as it is the machine closest to ITER. “If this internationalisation is accomplished, then JET has a good chance of being kept operational beyond 2018” says Lorne Horton.