Determination of the dynamic characteristics of aerogels in the energy-release zone of a high-power electron beam

The dynamics of the interaction of a high-current electron beam with SiO2 a erogels of different density and porosity are investigated by optical metho ds. A model for describing highly porous materials is developed on the basi s of the information obtained regarding the unloading of aerogels in the en ergy-release zone of an electron beam, as well as the measured energy-relea se profiles. A corresponding nonlinear self-consistent equation of state is obtained which reflects the fractal properties of aerogels and permits det ermination of the thermodynamic characteristics of aerogels as the porosity varies tens of times. The influence of electric space charge on the energy -absorption profile of a high-power electron beam in aerogels of different density is discussed. (C) 1998 American Institute of Physics. [S1063-7842(9 8)02010-8].