Abstract: In an Ebeam system, the cathode assembly and/or the window assembly can be simply and quickly replaced or exchanged as required by conditions of use, without replacing the vacuum chamber, or other component systems. In some cases, replacement may be made without removing the vacuum chamber from its installed position. As a result, the cathode assembly and the window assembly can be readily changed over for maintenance. In addition, modular replacement cathode assemblies and window assemblies having varying characteristics may be selected to match a specific desired application, and then installed into the system. The system may be designed as a compact and lightweight portable device.