A system of measuring ion beam current in a process chamber using conductive liners is disclosed. A conductive liner is used to shield the walls of the process chamber. An ion measuring device, such as an ammeter, is used to measure the current created by the ions that impact the conductive liner. In some embodiments, a mechanism to contain secondary electrons generated in the process chamber is employed. Additionally, the ions that impact the scan system or workpiece may also be measured, thereby allowing the current of the entire ion beam to be measured.