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The International Fusion Material Irradiation Facility (IFMIF)[1] is an international scientific research program designed to test materials for suitability for use in a fusion reactor. The IFMIF, planned by Japan, the European Union, the United States, and Russia, and managed by the International Energy Agency, will use a particle accelerator-based neutron source to produce a large neutron flux, in a suitable quantity and time period to test the long-term behavior of materials under conditions similar to those expected at the inner wall of a fusion reactor.

In order to achieve this, it is necessary to dispose of a specific neutron source mimicking the nuclear reaction between deuterium and lithium nucleus. The conceptual design of such an irradiation facility started in the 90’s and has been developed in an international environment under the name of IFMIF. This is one of the key facilities required to design a DEMO reactor, which will be based not only on the information obtained from ITER, but also on the information regarding the behaviour of materials under the expected neutron irradiation, as provided by IFMIF. Therefore, IFMIF is an essential part of the international effort to achieve Fusion as a viable energy source.

The design of IFMIF is based on a high energy deuteron beam which impacts on a lithium target, yielding neutrons as a product of stripping nuclear reactions. In order to produce the required amount of energetic neutrons required to reach significant values of damage rate, a deuteron beam with an energy of 40 MeV and a current of 250 mA is required. In order to avoid the problems associated with high current accelerators, as much as possible, the design is based on a double beam consisting of two linear accelerators with 125 mA of current each. Still, these are the most powerful particle accelerators under constructions nowadays.

Three different areas, clearly identified, define the challenges of the design and the construction of IFMIF, each of them presenting specific difficulties:

  • The accelerator system: with the capacity of providing two 40 MeV deuteron beams with currents of 125 MA each.
  • The lithium loop, i.e., the liquid lithium target for the deuteron beam, where the neutrons will be produced and the heat deposited by the double deuteron beam must be dissipated.
  • The systems of the materials irradiation area, which should be able to exploit the generated neutrons in order to test materials samples while controlling the temperature. The irradiation area should also provide suitable radiation shielding, for security reasons.

See also