Design and implementation of superconducting cavity coupler RF conditioning platform control system for CSNS-II

Abstract

According to the upgrade plan of CSNS-II (China Spallation Neutron Source Phase II), the beam power on target of CSNS needs to be increased to 400 kW in the future. In order to achieve this goal, a superconducting acceleration section will be added behind the LINAC (Linear Accelerator) section of CSNS-I. The superconducting acceleration section includes two superconducting cavity types operating at 324 MHz and 648 MHz. At present, the 324 MHz superconducting cavity couplers have been produced. In order to perform the RF conditioning and test the power transmission capability of the coupler, we designed and built a corresponding automatic RF conditioning control platform in the gallery of CSNS LINAC. The control system hardware is based on Micro TCA (Micro Telecommunications Computing Architecture, MTCA) LLRF (low-level radio frequency) control system, and the software development is based on EPICS (Experimental Physics and Industrial Control System). PLC (Programmable Logic Controller) based data acquisition and monitoring slow protection system, in-house developed interlocking fast protection system and some general equipment constitute the main hardware facilities, while EPICS IOC (input and output controller) and CSS (Control System Studio) OPI (Operator Interface) constitute a main pillar of control software. The control logic of the RF conditioning program mainly uses the vacuum pressure readings collected from the coupler as the judgment standard, and controls the power autonomously according to the real-time vacuum data, which can largely avoid human misoperation and greatly reduce the operator’s workload. At present, the system has started to run, and the actual work results show that its hardware and software performance are excellent, which ensures the safe and smooth progress of the RF condition process. In this article, we will first introduce the hardware architecture of the entire system, secondly introduce the software architecture and control logic of RF conditioning, and finally give the actual working results of the control system.