HELOKA facility: Thermo-hydrodynamic model and control

This paper presents the thermal-hydrodynamic model used to simulate the behavior of the Helium Loop Karlsruhe (HELOKA) facility and describes the mechanism used to control various loop parameters. An accurate control of the temperature during the warm-up and flat top phases is achieved solely by controlling the heater power. During testing campaign, when the helium flow has to be cooled, the power of the heater is set to zero and the temperature is controlled using a control valve installed in the by-pass of the heater. The adopted solution reduces the harmonic distortions when operating at reduced power while keeping the investment cost low.