New 30-m Flexible Hybrid Energy Transfer Line With Liquid Hydrogen and Superconducting Cable—Development and Test Results

In the framework of the second stage of the Russian R&D program for the development of hybrid energy transfer lines (HETLs), the new 30-m MgB₂ superconducting cable with high voltage insulation has been developed and tested. The superconducting cable was inserted into a newly developed flexible 30-m hydrogen cryogenic line that has three sections with different types of thermal insulation in each section. High-voltage current leads were also developed. The superconducting cable, cryostat, and current leads have been tested in October 2013. Cable critical current was ~3500 A at ~21 K. Cable and current leads passed a high voltage test with 50-kV dc at liquid hydrogen temperature. The tests were performed at temperatures from 20 to 26 K, hydrogen flow from 70 to 450 g/s, and pressure from 0.25 to 0.5 MPa. It was found that the active evaporating cryostatting system as a thermal insulation practically eliminated heat transfer from room temperature to liquid hydrogen. The flexible 30-m HETL developed is able to deliver ~ up to 60 MW of chemical power and ~75 MW of electrical power, i.e., ~135 MW in total. MgB₂ cable design and test results of hybrid energy transfer lines are presented and discussed.