RF control and instrumentation for particle accelerator

For efficient and stable operation of particle accelerator, a modern state of art Control and Instrumentation systems are required. Among many systems most important ones are Low Level RF (LLRF) control system, Beam Position Monitor (BPM) system, and RF protection & Interlock (RFPI) systems. LLRF system controls amplitude and phase of RF cavity electric field. At high power operation, RFPI system plays major role of protection and post fault diagnosis. BPM electronics measures and monitors beam parameters. Some of the systems developed indigenously, and also as part of International collaborations will be presented. These include LLRF system for BARC-TIFR linac, low energy high intensity proton accelerator (LEHIPA), Horizontal Test Stand (HTS) and as part of Indian Institutions of Fermilab Collaboration (IIFC), BPM for SPIRAL2 and RFPI for LEHIPA, HTS and as part of IIFC. The talk will introduce some of the salient features of these systems. A few modern control techniques required to achieve high amplitude and phase stability of RF cavity electric field will also be introduced. To name a few, Iterative Learning Control (lLC) technique, predistortion linearization of Solid State Power Amplifier (SSPA), etc. help improve control performance. ILC is useful for repetitive disturbance rejection due to beam loading, Lorentz Force detuning, etc. For predistortion of RF signals as drive to SSPA, RF power amplifier or Klystron input-output characteristics are captured and modelled. Subsequently, an appropriate estimation technique needs to be employed to achieve amplitude and phase linearization. These techniques, their benefits and challenges involved will be briefly summarized. This talk will cover activities carried out by team at ACSS, ACnD, BARC over a long duration. (author)