Direct observation of space charge evolution in e-irradiated Kapton films

The pressure wave propagation method has been applied to analyze the evolution of the space charge in e-irradiated Kapton H films. The 125 mu m thick films are irradiated in a vacuum chamber with a monoenergetic electron beam in the 10-50 keV energy range. The method allows the direct observation of the depth of penetration of electrons. First results on Kapton are presented. The space charge evolution in the irradiation and nonirradiated regions is studied during and after the irradiation process. Trapped electrons drift in the nonirradiated zone towards the electrode interface where they build up. Positive charges appear in the bulk of the sample both in the irradiated and nonirradiated regions.<
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