Determination of the evolution of the surface potential of a charging insulator by measuring the intensity of its X-ray characteristic peaks

The charge developed in an insulator by an electron beam has often been studied by following the evolution of the secondary electron emission of the target. However this latter proves to be insufficient when one attempts to correlate it with physical properties of the sample such as its density of traps and their spatial distribution. An important step would be to have access to the time evolution of the surface potential Vs(t). However, this latter quantity is not easy to measure. In this paper, we propose a new method to measure the evolution of the surface potential by relating it to the X-ray emission induced by the electronic bombardment. More exactly, we show that there is a relation between the intensity of the characteristic peaks and the potential existing under the beam impact at a given instant of the charge. After having explained the method, we check its validity both experimentally and also by comparison with Monte Carlo simulations. We then present initial results obtained for amorphous SiO2 targets