The governing body of the international fusion energy experiment ITER – the ITER Council – has just approved an updated design, which also means that a diagnostic system called Collective Thomson Scattering (CTS) will be part of the ITER experiment. The diagnostic has been developed by the fusion research group at Risø DTU.

Fusion energy is the energy source of the sun and the stars. ITER aims to demonstrate that we can use fusion energy as an energy source directly here on earth. If this succeeds, we will have a safe, sustainable and abundant energy source (the fuel comes from seawater and lithium).

ITER is expected to be completed in 2018. It is the largest international research project since the International Space Station, ISS. The fusion experiment is being built in Cadarache in southern France as a collaboration between the EU, India, Japan, China, Russia, South Korea and the United States. Several other countries have shown interest in participating in the project.

The original design of ITER was ready back in 2001, so the ITER management chose to review the design to ensure the best solutions before the construction begins. The result of this ”design review”, the consequences for the project schedule and the allocation of tasks were presented at a meeting in Mito, Japan on 17-18 June and approved by the governing body of the ITER organisation, the ITER Council.

Measurements to teach us about the physics of plasma
Additional diagnostic methods have been included in the updated design to be used to explore the 200 million degrees hot plasma in the fusion experiment. The extremely high temperature is obviously a challenge, and one cannot use ordinary measurement methods.

Collective Thomson Scattering (CTS) works by injecting a microwave beam of a few centimeters in diameter and with a power of 1 MW – equaling more than 1000 microwave ovens at full power – into the plasma. There it interacts with small plasma waves, and the result is observed by a set of antennas. These signals help the scientists to determine how the highly energetic particles in the fusion plasma move.

Risø heads international collaboration on CTS
The CTS diagnostic method has been developed over a period of several years in an international collaboration on experiments, in Europe in particular. Since 2001 Risø has taken a leading role in this collaboration. The fusion group at Risø runs and utilises CTS diagnostic systems in connection with two smaller fusion experiments in Germany. The technology is constantly evolving and may eventually be able to measure more characteristics in the plasma.

Since 2003 the Risø group has been working on contracts from EFDA (European Fusion Development Agreement) to develop a conceptual design for a CTS diagnostic for ITER. This preliminary design was part of the mentioned design review and now central parts of this diagnostic have been included in ITER’s so-called baseline design.

It has been decided that the final development and production of the instrument is to be carried out by Europe via Fusion for Energy which is the organisation responsible for the European participation in ITER. The fusion group at Risø is hoping to achieve contracts with Fusion for Energy in order to become a key player in the final development of CTS for ITER.

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Source : RISO