A Cookbook for Building a High-Current Dimpled H− Magnetron Source for Accelerators

A high-current (>50 mA) dimpled H^- magnetron source has been built at Fermilab for supplying H^- beam to the entire accelerator complex. Despite many decades of expertise with slit H^- magnetron sources at Fermilab, we were faced with many challenges from the dimpled H^- magnetron source, which needed to be overcome in order to make it operational. Dimpled H^- sources for high-energy physics are not new: Brookhaven National Laboratory has operated a dimpled H^- source for more than two decades. However, the transference of that experience to Fermilab took about two years because a cookbook for building this type of source did not exist and seemingly innocuous or undocumented choices had a huge impact on the success or failure for this type of source. Therefore, it is the goal of this paper to document the reasons for these choices and to present a cookbook for building and operating dimpled H^- magnetron sources.