Investigation of ITER TF Conductor Hydraulic Resistance

Conductors for winding ITER toroidal field magnets are cable-in-conduit type where multi-stage petals are twisted around central cooling spiral inserted into stainless steel jacket. Every conductor unit length and its components pass various tests during manufacturing and the final acceptance test consists of 760 m or 415 m long conductor global leak test and an investigation of conductor hydrodynamic performances. The hydraulic resistance is one of the main TF CICC´s parameter to provide sufficient cool down and stable work of the magnet system during operation. Starting from 2011, when the first copper Dummy conductor was completed, 22 conductors in total were tested in a test facility that was designed and manufactured at National Research Centre “Kurchatov Institute.” A scheme of the pressure drop test facility, measurements technique and results of mass flow rate measurements depending on inlet and outlet pressure difference are presented in this work. Measurements were carried out by flowing nitrogen gas through conductor at room temperature. However, in accordance with the theory of turbulent self-similarity it is possible to develop a simple criterion for estimation of hydraulic resistance at any temperature. The model of two parallel independent flows has been used. The simple explanation of mass flow rate non-linearity at small pressure difference has been provided.