Nouvelles techniques d'analyse des phénomènes de charge dans les diélectriques en environnement spatial – Matspace

1- Scientific background and objectives. Dielectric materials are commonly used in the structure of satellites. By nature, they can easily get electrically charged while they are submitted to various radiation sources. Under specific conditions, these internal of surface can lead to electrostatic discharges that can affect the embarked electronic equipments or modify the dielectric material properties. It is therefore important to be able to describe and model charge accumulation and transport phenomena and besides describe the discharge phenomena (slow or fast) in material used in a space environment. 2- Description of projet, methodology. To do so, a special set-up has been developed at ONERA (the irradiation chamber SIRENE) to simulate the electronic irradiation conditions in space. Electrons (from 0 to 400 keV) are delivered by coupling a 35 keV electron gun and a Van de Graaff accelerator. This chamber is equipped with electric measurement detection systems such as the surface potential probe or the conduction current though the irradiated specimen. Recently, a pulsed electro-acoustic device (PEA) that allows to probe internal charges, in the spatial and time domain during and after the irradiation, has been developed (the spatial resolution is about a few µm and the time resolution is of the order of seconds). In order to obtain complementary and more accurate information on charge behaviour near the irradiated surface we intend to realise in-situ measurements by the Laser Intensity Modulation Method (LIMM°. This technique is already used in the laboratory for other studies. On the other hand as the SIRENE chamber is often used for long time studies, we intend to install a new irradiation chamber equipped with a lower energy electron gun (100 keV) for preliminary studies. 3- Expected results. The use of this advanced technology, the development of a new PEA measurement set-up (with measurements under floating potential) and the analysis of data obtained by the LIMM method, should allow the precise characterization of storage, transport and disruption phenomena during the irradiation and the relaxation after the end of the irradiation. On the bases of these observations, we will try to describe phenomena occurring during the irradiation – Radiation Induced Conductivity – and after irradiation – slow and fast relaxation of the charges in a large set of materials used for space applications, under various irradiation conditions (energy, dose, UV, temperature).