Commissioning Plan of the IFMIF-DONES Accelerator

IFMIF-DONES (International Fusion Materials Irradiation Facility- DEMO-Oriented Neutron Early Source) - a powerful neutron irradiation facility for studies and certification of materials to be used in fusion reactors - is planned as part of the European roadmap to fusion electricity. Its main goal will be to characterize and to qualify materials under irradiation in a neutron field similar to the one faced in a fusion reactor. The intense neutron source is produced by impinging deuterons, from high-power linear deuteron accelerator, on a liquid lithium curtain. The facility has accomplished the preliminary design phase and is currently in its detailed design phase. At the present stage, it is important to have a clear understanding of how the commissioning of the facility will be performed, especially the commissioning of a 5 MW CW deuteron beam, together with the lithium curtain and the beam optimization for the neutron irradiation. In this contribution, the present plans for the hardware and beam commissioning of the accelerator will be given, focusing on the most critical aspects of the tiered approach and on the integration of the procedure with the lithium and tests systems

A giant exoplanet orbiting a very-low-mass star challenges planet formation models

Surveys have shown that super-Earth and Neptune-mass exoplanets are more frequent than gas giants around low-mass stars, as predicted by the core accretion theory of planet formation. We report the discovery of a giant planet around the very-low-mass star GJ 3512, as determined by optical and near-infrared radial-velocity observations. The planet has a minimum mass of 0.46 Jupiter masses, very high for such a small host star, and an eccentric 204-day orbit. Dynamical models show that the high eccentricity is most likely due to planet-planet interactions. We use simulations to demonstrate that the GJ 3512 planetary system challenges generally accepted formation theories, and that it puts constraints on the planet accretion and migration rates. Disk instabilities may be more efficient in forming planets than previously thought

Challenges of Target and Irradiation Diagnostics of the IFMIF-DONES Facility

International audienceIFMIF-DONES will be a first-class scientific infrastructure consisting of an accelerator-driven neutron source delivering 1e17 n/s with a broad peak at 14 MeV. Such neutron flux will be created by impinging a continuous wave 125 mA, 40 MeV, 5 MW deuteron beam onto a liquid Li jet target, circulating at 15 m/s. Material specimens subjected to neutron irradiation will be placed a few millimeters downstream. Some of the most challenging technological aspects of the facility are the Diagnostics to monitor the Li jet, beam parameters on target, and characterization of the neutron irradiation field, with transversal implications in the scientific exploitation, machine protection and safety. Multiple solutions are foreseen, considering among others, Li jet thickness measurement methods based on optical metrology and millimeter-wave radar techniques, Li electromagnetic flowmeters, beam footprint measurements based on residual gas excitation, online neutron detectors such as SPNDs and micro-fission chambers, as well as offline neutron fluence measurements by activation foils or spheres. This contribution provides an overview of these aspects and the associated R&D activities