Photo: RBIA dual ion beam facility, which enables two ion beams from different accelerators to be combined simultaneously, has been inaugurated in Zagreb. The facility strengthens Croatia’s fusion research and expands the global supply of facilities with such cutting-edge capabilities, the International Atomic Energy Agency (IAEA) reported on 11 July.

The Ruđer Bošković Institute’s (RBI’s) He Ion Source & DiFU Dual-Beam Facility was installed with IAEA support. It will help scientists test and develop new structural materials for fusion energy to become a reality, IAEA said. There are only a very few facilities of this kind – 12 worldwide, of which only four are in the European Union (EU).

RBI has been working with the IAEA through a collaborative agreement signed in 1997, and the Agency has provided the Institute with equipment and assistance through a capacity building programme.

The IAEA recently launched a new coordinated research project to facilitate experiments at ion beam facilities worldwide.

Fusion reactions generate high energy neutrons and alpha particles which, after some time of exposure, can damage reactor walls. Ion beam technology like the dual-beam facility in Croatia can simulate these extreme conditions and help to develop new materials sturdy enough to sustain them. “Installation of the He ion source at the smaller 1.0MV tandem accelerator was the last missing component at the RBI accelerator facility, which is now capable of performing the most realistic simulation of the fusion environment,” said Milko Jasic, Senior Scientist at RBI’s Laboratory for Ion Beam Interactions. “This investment will also enable increased use of ion beam analysis techniques for a wide range of other applications.”

“It will allow researchers and engineers to test that materials are robust enough to contain a fusion reaction, among other things,” added Danas Ridikas, Head of the Physics Section at the IAEA. “The facility is good news for Europe and for IAEA Member States in other regions too.” However, important questions remain. “For example: how can we know that materials will be strong enough to withstand a fusion reaction after years and years of exposure?” Ridikas said. 

Technology like the dual-beam ion facility in Croatia can simulate similar circumstances, incuding transmutation products and damage produced by high-energy neutrons and alpha particles that come from fusion. “With the right measurements, right temperature control, and two simultaneous ion beams — hence, dual beam — hitting the material, we are creating a simulated reality where we can get an indication of how the structural material will react to the force of fusion,” Ridikas said. “This way, we can test which material holds up and for how long.”

RBI Director General Dr David M Smith said: ''The uniqueness of the equipment will allow for new gain of foreign researchers and further upgrade the quality of research that will be financed under Horizon 2020 programme, such as the EUROfusion and RADIATE projects, as well as the IAEA projects and the CERIC-ERIC consortium.'' 

Last month, the IAEA and the ITER International Fusion Energy Organisation agreed to strengthen cooperation in nuclear fusion research and related activities with the long-term goal of realising fusion energy production on the industrial, power-plant scale experimental reactor under construction in France. In parallel, dual-beam facilities such as the one at RBI, or the new EU-led DONES initiative in Spain, a fusion-dedicated neutron source, will advance research in materials testing.

RBI’s DiFU will serve as a DONES accompanying device, taksed to perform a pre-selection of materials to be tested on DONES. "Due to expected high operation costs of DONES it would be necessary to carefully select which materials would be sent to DONES for irradiation and testing," said Dr Tonči Tadić, Coordinator of the Croatian Fusion Research Unit. "We hope that the DiFU may be used for such purpose, he added, noting that until DONES is completed the required irradiations of fusion materials could be done either in dual-beam facilities or in fast research reactors.

"DONES is a complex facility, and it will take at least 8-10 years to construct it and come to first materials that can be tested under a 14MeV neutron flux. If we don't start testing the new materials that we will use to build DONES, we will be lagging behind with the whole project," noted Professor Tony Donne, EUROfusion Programme Manager.

"DiFU shall play an important role in the verification of the EU irradiation effect modelling programme (IREMEV), closing the gap between science and engineering," he added.

Photo: Inauguration of Ruđer Bošković Institute’s He Ion Source & DiFU Dual-Beam Facility (credit: RBI)