The use of dose and charge distributions in electron beam processing

Abstract

Absorbed dose distributions in products treated with energetic electrons are influenced by the electron energy, the atomic composition of the material, the size and shape of the product and its orientation to the electron beam. Dose distributions can be measured by placing small dosimeters at various positions within some products, but more detailed data can be calculated with Monte Carlo codes that are readily available. For high-dose treatment processes, the magnitude and internal distribution of electrostatic charges may be significant. The accumulation of high charges could cause discharges through some materials, which could damage the products. This effect can be avoided by using electrons with sufficiently high energy, so that most of them will pass through the material. Charge distributions are difficult to measure, but they can be calculated with the Monte Carlo method. Dose and charge distributions with a wide range of electron energies in typical materials are presented in this paper. These have been obtained with the Integrated Tiger Series of Coupled Electron/Photon Monte Carlo Transport Codes (ITS). The data illustrate the effects of electron energy and material composition. These quantitative results will enable users to determine the electron energy, beam current and beam power requirements for a variety of electron beam treatment processes.