Approximation of Range in Materials as a Function of Incident Electron Energy

A simple composite analytic expression has been developed to approximate the electron range in materials. The expression is applicable over more than six orders of magnitude in energy (10 MeV) and range (10-9 m to 10-2 m), with uncertainty of ≤20% for most conducting, semiconducting and insulating materials. This is accomplished by fitting data from two standard NIST databases [ESTAR for the higher energy range and the electron IMFP (inelastic mean free path) for the lower energies]. In turn, these data have been fit with well-established semi-empirical models for range and IMFP that are related to standard materials properties (e.g., density, atomic number, atomic weight, stoichiometry, band gap energy). A single free parameter, the effective number of valence electrons per atom Nv, is used to predict the range over the entire energy span. Index Terms—range, inelastic mean free path, spacecraft chargin