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In order to study the behavior of dielectric materials under an electronic bombardment, a new irradiation chamber has been designed and lately constructed in the laboratory. In a near future, this chamber will be equipped with various experimental set-up allowing measurements in-situ. The aim is to combine complementary information to get a better knowledge on charge transport, storage and release in insulating materials in relation to the electron beam energy and flux. In this paper, we briefly describe the irradiation chamber, and we present our first results obtained by Pulse Electro-Acoustic (PEA) method and by Focussed Laser Intensity Modulated Method (FLIMM) on Polytetrafluoroethylene (PTFE) films after irradiation under a low energetic electron beam.

A technique for three-dimensional cartography of space charges profiles inside polymer insulating samples is proposed. Called focused laser intensity modulation method (FLIMM), it is derived from the well-known LIMM method, with an additional possibility of being able to focus the laser spot on the surface of the sample to be studied. The processed data is a short-circuited pyrolectric current collected between the electrodes and induced by the interaction of the charges with the periodic variations of temperature produced by the laser source. The focused aspect of our method requires a good three-dimensional modelling of the spatial evolution of this thermal gradient. Under these conditions, the treatment of the equation of heat propagation is carried out using simultaneously a double Fourier transform and Green functions. In association with the numerical simulations of this solution, a two-dimensional scanning of the beam on polyethylene test sample surfaces shows that one can get three-dimensional representations of space charge shapes with a lateral resolution lower than 10 μm and for a depth of analysis typically included in the range 1–100 μm.

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Dielectric materials are used as thermal regulator on satellites, as they offer for the embarked electronic devices the required protection. Their behavior in space environment must be studied in order to prevent electrostatic discharges that can be harmful for satellites. An irradiation chamber called MATSPACE has been built to study these materials. It is equipped with various material characterization devices. We will focus this paper on the Laser Intensity Modulation Method (LIMM) and the Split Faraday Cup (SFC) arrangement in the chamber. In a first approach it was necessary to reconsider the thermal aspect of the LIMM data treatment as it was now used under vacuum. In a second step, a new deconvolution treatment has been developed in order to recover the charge profile near the surface and further in the bulk. The influence of frequency range in which the signal is recorded will be also presented.