Thermal Performance Analysis and Measurements of the Prototype Cryomodules of European XFEL Accelerator - Part I

The European X-Ray Free Electron Laser (XFEL), the research facility currently under construction in the Hamburg area, Germany, is based on a superconducting linear accelerator that brings electrons to almost the speed of light. The linear accelerator consists of 100 accelerating cryomodules (CMs) operating at the temperature of 2 K. The thermal performances of the accelerator CMs are a key element to determine the heat load budget, the required capacity and the cost of the XFEL refrigerating system and to guarantee its efficient operation. The measurement of the thermal performances of the CMs is also an important step in the qualification of the CMs during the series production.This paper describes the thermal performance analysis of the European XFEL prototype cryomodules. The analysis takes into account all the main contributors (multilayer insulation, current leads, power couplers, support posts, and cavities) to the static and dynamic heat loads at various cryogenic temperature levels.Existing empirical databases are reviewed and used to evaluate the heat transfer through the multilayer insulation and numerical simulations are developed to investigate the heat loads generated from the different CM components