Improvements to the Cavity Simulator for European Spallation Source

The Cavity Simulator for the European Spallation Source (ESS) is a specialized device created to evaluate the Low-Level Radio Frequency control systems utilized in the medium- and high-beta sections of the ESS’ linear accelerator (linac). This equipment replicates the behavior of a single RF station, including a high-power RF amplifier and a superconducting cavity with piezo tuners. This is the world’s first device capable of providing such complex functionalities and simulation scope. The device was used to install LLRF control systems in dedicated sections of the ESS’ linac. The Cavity Simulator is continuously being developed to extend its scope and functionality. This paper presents some recent improvements implemented in this device. These include slow resonance frequency drift simulation, beam current, amplifier nonlinearity, data acquisition system, and synchronization. In addition, the device hardware and operating principles are discussed, along with the measurement results that demonstrate the proper operation of the designed system.