A method of setting up a medium current ribbon beam for ion implantation is provided. It includes providing an ion source fed with a process gas and a support gas. The process ion beam is separated from the support gas beam with a mass analyzing magnet, and the intensity of the process ion beam is controlled by varying the ratio of process gas to support gas in the ion source gas feed. Process beam intensity may also be controlled with one or more mechanical current limiting devices located downstream of the ion source. An ion beam system is also provided. This method may control the total ribbon beam intensity at the target between approximately 3 uA to about 3 mA.