Samuel Peillon and Mamadou Sow, engineers of the IRSN's Aerosol Physics and Metrology Laboratory (Laboratoire de Physique et de Métrologie des Aérosols, SCA / LPMA) received the Best Poster Award at the 22nd European Aerosol Conference (EAC 2016), held between the 4th and the 9th of September in Tours.
The award winning poster relates to experimental work conducted within the framework of an exploratory research project related to the safety of the
ITER tokamak. The two scientists studied the electrostatic behaviour of tungsten dust that is representative, in terms of size, of those usually produced by the erosion of the tokamak divertor1 subjected to the action of plasma. The presence of tritium in this dust can lead to their electrical self-charging and thus modify their capacity to adhere to the walls, by making them sensitive to electrostatic forces, which is a factor that influences their re-suspension and therefore their potential release to the environment in the event of an accident.
The experiments at the LPMA that received the award at the EAC-2016 have in particular enabled the determination of the electrical field threshold levels needed - around 20 kV/cm - to overcome the adhesion forces between tungsten particles with sizes of the order of microns and a conductive metal surface. Furthermore, they have shown that a very thin layer of oxide on the particle surface, with a thickness not exceeding 2 to 3 nm, is enough to render them dielectric. This reinforces the hypothesis of electrically self-charging particles, if these contain tritium.
These results will ultimately improve the modelling of dust re-suspension by turbulent flows, taking into account electrostatic interactions. In addition, they will contribute to a better understanding of the behaviour of the dust produced in ITER, in order to enable the implementation of appropriate safety and radiation protection measures to prevent their dissemination in the event of an accident or when conducting maintenance during normal operation.
The LPMA has thus shown that it is a major actor in aerosol science in France and abroad. It was also in this laboratory that Anthony Rondeau completed last year the thesis work for which he received the
Jean Bricard award.
1. The ITER tokamak divertor extracts the effluent gases and impurities, as well as a portion of the heat generated by the fusion reactions.
Photo: Samuel Peillon (2nd from the left side) during EAC-2016 © IRSN