DESIGN METHODOLOGY OF LONG COMPLEX HELIUM CRYOGENIC TRANSFER LINES

Abstract

Big scientific facilities, like superconducting particle accelerators or fusion reactors require high cooling power, usually produced locally by large helium refrigerators and transferred, by means of liquid or supercritical helium, over the distances that may exceed several kilometres. Construction of cold helium transfer lines should take into consideration many different issues. The lines are exposed to thermal loads which can constitute an important part of the cryogenic system thermal budget. Pressure difference between the vacuum insulation and the inner content of the pipes causes significant mechanical stresses. The cyclic changes of temperature can lead to considerable fatigue stresses. Additionally, due to complex structure of the scientific facilities, the access to the cryogenic lines can be partly or totally limited. Therefore all these thermal and mechanical aspects have to be analyzed and compromised during the design phase of the complex helium transfer line.The paper presents a design methodology of long multi‐channel helium cryogenic transfer lines. It describes some aspects of process line arrangement, thermo‐mechanical calculation, supporting structure and contraction protection, taking as a case study cryogenic transfer line XATL1, dedicated for the Accelerator Module Test Facility (AMTF) of the European X‐rays Free Electron Laser (XFEL).