Materials exposed to the space plasma environment acquire electric charge, which can have harmful effects if it leads to arcing or electrostatic breakdown of important spacecraft components. In fact, spacecraft charging is the leading environmentally induced cause of spacecraft anomalies. This study focuses on measuring electron yield, a property of materials that describes how many electrons are ejected from a material under energetic electron bombardment, which can vary depending on the energy of incident electrons. Intrinsic electron yield is defined as the average number of electrons emitted per incident electron from an electrically neutral material. The specific aim of this work is to improve yield measurements for insulator materials, which can be difficult to test using conventional methods due to charge accumulation in insulators.Most studies of electron yield use a steady current electron beam in a vacuum chamber to irradiate materials to be tested. By comparing the amount of current deposited in the material to the total incident current, the emitted current can be calculated. This works well for conductors; however, insulators charge up quickly, which either repel incident electrons or reattract emitted electrons producing erroneous yield measurements. This study improves on methods that use a pulsed electron beam to measure yield with small amounts of charge per pulse, as well as neutralization methods to dissipate stored charge between pulse measurements.The improvements to instrumentation and data analysis techniques are quantified to demonstrate their validity. These improvements will allow for continued studies on extreme insulator materials. Future studies will provide new understanding of interactions between electron radiation and materials, which will allow for better modeling of spacecraft charging and the development of materials that meet desired electron emission specifications.

<p> The interaction mechanisms of an ion beam with a solid target are identified. Basic parameters associated with ion scattering, charge neutralization, inelastic energy losses and secondary ion production are described. Low energy (1-20 kev) experimental studies on these topics are reviewed. A low energy ion mass spectrometer is described. The ion beam is generated by an existing kev ion accelerator and is directed to a newly constructed UHV target chamer. The energy and angular distributions of the backscattered particles are measured with a hemispherical electrostatic analyser and a channeltron detector. A high precision goniometer allows target rotation about two perpendicular axes by angles of 180° and 90° with an accuracy and repeatability of 0.1°. The interaction chamber is bakeable to 250°c and was designed for an ultimate pressure of 10^-11 torr. The data acquisition system chamber scans the energy spectrum automatically so that the radiation dosage at the target is equalized for all channels. </p> / Thesis / Master of Engineering (MEngr)