Contents 1 INTRODUCTION
As a product emerges from infancy in the laboratory and matures on the production floor, lessons learned from previous experiences, both good and bad, are frequently incorporated as design modifications. The result of this successive iterative growth is a genuinely improved product. Indeed, it is through this rationalized approach that the third-generation (3G) rf guns were born. Prior to the arrival of these injectors, the APS was using one first generation (1G) and one second-generation (2G) rf gun. Each alternated in the role of main injector and hot spare for reliable storage ring injection [1]. Both provided consistent and sufficient beam for our needs over the years they have been in service. However, a number of developments that occurred within the past year motivated us to procure a set of three state-of-the-art rf guns and to retire our present injectors. This also provided an ideal opportunity to redesign a few key features that had been troublesome in years past. Presentations on the physics and performance of the 1G and 2G S-band rf guns can be found in [2], [3], [4].
