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La Recherchev2


Evolution of ion concentrations downstream radioactive sources and the resulting aerosol charging.



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F. Gensdarmes, J. Malet, D. Boulaud, A. Renoux, European aerosol conference, 3-8 september 2000, Dublin (Irland).


Electrical properties of aerosols are quite important in different parts of aerosol physics, as metrology, transport modelling or inhalation studies. Aerosol charging in a bipolar ion atmosphere is often described by the Boltzmann equilibrium (Keefe et al., 1959). However many studies show that the aerosol charge distribution can differ significantly from this equilibrium (Pourprix 1973, Hoppel and Frick 1990). The asymmetry between positive and negative ion conductivity leads generally to a negative mean charge on the aerosol. Our interest is the knowledge of the ion asymmetry in order to model the aerosol charge distribution and its influence on the aerosol behaviour. The aim of this work is thus to study experimentally and numerically the evolution of the bipolar ion concentrations in a sampling line and to evaluate its effect on the aerosol mean charge distribution. The contribution of the numerical study is important in order to model the electrical properties of aerosols in a local or global way. Some particular interests are, for example, the wall effects, which influence the space charge and the electrical behaviour of aerosols in a containment.