Design and testing of the ISAC RFQ control system

A Digital Signal Processor-based control system has been designed and tested for use with the ISAC RFQ accelerator. This system uses a direct digital synthesizer and phase-locked loop to generate the 35 MHz nominal cavity frequency. One DSP provides both in-phase and quadrature control for the system. A second DSP operates the cavity tuning mechanism. A reference signal with digital controlled phase shift is output for use in the upstream cavity in the beam path, an 11.66 MHz prebuncher. The system incorporates spark and high Voltage Standing Wave Ratio detection and protection. It also includes operator-controlled hardware limiting, and visual feedback of operating conditions. The complete system including low-level RF components is housed in a VXI rack. Turn-key operation is achieved via a supervisory control, which consists of a Windows-based server. This server broadcasts system status using User Datagrams, and listens on control commands via TCP. Network-aware database objects interpret these messages to provide control and display of the system operating parameters.