Design and development of the S-band high power test stand for multi-purpose applications at IHEP

Abstract

A multipurpose S-band high-power test stand (HPTS) developed at the Institute of High Energy Physics (IHEP) of China is routinely used for radio-frequency (RF) conditioning of couplers and resonant structures, as well as other high-power experiments in the S-band frequency regime. The HPTS with a peak power of 230 MW was developed to meet requirements of various applications with multiple frequencies (2856 MHz/2998 MHz) and power levels (45 MW/50 MW/65 MW/80 MW) for different accelerator projects at the IHEP, e.g. the High Energy Photon Source (HEPS), Beijing Electron Positron Collider (BEPCII), Circular Electron Positron Collider (CEPC). This paper describes the design and implementation of the system in detail. The highlight of the HPTS is the impedance-matched design to accommodate different impedances, allowing a single pulse modulator to supply different types of klystron loads. The control system, developed under the Experimental Physics and Industrial Control System (EPICS), adopts a combination of Micro Telecommunications Computing Architecture (MTCA) based low-level RF system (LLRF) and programmable logic controller (PLC) based interlock unit controllers, and enables a real-time data acquisition and visualization. To ensure a high reliability and high-gradient RF power conditioning, the interlock unit integrates various protection features, like the short circuit load, high standing wave ratio, low vacuum, arcing detector, and abnormal dark current. It is worth mentioning that the entire conditioning procedure can be performed unattended automatically controlled. The test stand has been operated stably for more than 7,000 hours for many rounds of high-power RF conditioning with different power/frequency requirements, which indicates that the HPTS can provide a stable, reliable, and automatic high-power testing for the development of S-band related devices.