Electron beam dynamics for the ISIS bremsstrahlung beam generation system

Abstract

An electron beam transport system was designed for use in the Bremsstrahlung Beam Generation System of the Integrated Stand-off Inspection System (ISIS). The purpose of this electron transport system was to provide for electron beam diagnostics and energy selection while also positioning the electron beam on a target down range. The transport system and its component magnets were designed using the TRANSPORT, Poisson, and Opera 3D codes, as well as several custom Python scripts. By implementing several methods in each part of the design process, it was possible to design the electron transport system to the exact specifications of the ISIS electron beam. This careful and iterative design process was documented in such a way to facilitate future beam transport design both at the MIT Plasma Science and Fusion center and elsewhere. This design process resulted in a beam transport system composed of three irondominated resistive-coil electromagnets. The system was designed for beam momentum up to 60 MeV/c and emittance of order 20 mm-mrad. Through magnetic field simulation and beam transport in 3D, a ID matrix code which tracks individual particles was developed. This code agreed with more detailed beam calculations and should allow for rapid beam simulation during system testing and operation.