Overview of the PBX-M plasma control system upgrade

The PBX-M group is developing a control system to integrate multiple independently-operating and mutually-interacting systems used for plasma control. Central to this effort has been the procurement of a SKYbolt 1 Shamrock AP computing platform as the Central Control Unit (CCU). The engineering and experimental effort for this program will occur in two phases. In Phase I of the program a minimum hardware configuration will be used to duplicate the functionality of the existing PBX-M plasma shape, current, and radial and vertical position control systems on the CCU. Phase II will expand the hardware configuration increasing the number of slow (10 kHz) A/D data acquisition channels and adding 32 fast (250 kHz) A/D channels. The expandable hardware system will facilitate integration of and improvements to the individual Phase I control systems and allow us to pursue topics in advanced discharge control (e.g., MHD control, disruption avoidance, and profile control and modification). In this paper we present an overview of the PBX-M plasma control system program. We discuss the properties of the Phase I and II processes and how they influenced our choices for the system's hardware and impact the software design. Also important are the increased general computing capabilities afforded by our choice of hardware and the impact it have on our between shot analysis capabilities. We also describe the Phase I control processes and present some details of their implementation.