This paper describes the design, development, and operating experiences using the Digital Plasma Control System (DPCS) on the Tokamak Fusion Test Reactor (TFTR). In the past year the DPCS has been used for three different control applications on TFTR : plasma position and current control, impurity gas injection feedback control, and piezoelectric valve control using pulse width modulation.

The DPCS is a VME-based control system which includes a "host" computer, and, high speed realtime I/O and processing capabilities. The system's hardware and software architecture was predicated on industry standards, modularity, and the use of Commercial Off The Shelf (COTS) products. The validity of these principals have been demonstrated through the rapid development and successful operation of the aforementioned applications.

The DPCS is a stand-alone system because it provides facilities for system development, operation, and data visualization. Conversely, significant integration into the established central computer control and data management systems as well as tokamak operations methodology was required. During the period of DPCS development, TFTR was within months of completion of its experimental program. This placed bounds upon the system's achievable design goals, especially regarding integration with the TFTR Machine State Database and the operator interface (GUI). A summary of the operator's experiences with the partially-formed system will be presented.

This paper will describe the three TFTR applications, including block diagrams of the hardware, both the host and realtime software, the user interface, and measured performance. Extensions to the DPCS software to enhance its effectiveness will also be described.

*Supported by US DoE Contract No. DE-AC02-76-CHO3073.