Recently, the S-Bend superconductive cable prototype has passed the first round cryogenic insulation test, marking a further step forward in ASIPP’s ITER feeder. More tests will be done in coming days to assure its insulation reliability.

The test is jointly conducted by Tokamak Design Division and R&D Center. For the test, the R&D Center, with cooperation from Tokamak Design Division and Hefei Cryogenic Vacuum Nutech Co. Ltd, developed withstanding voltage testing platform which can provide the cryogenic Paschen condition and do S-Bend cryogenic insulation test.

During the test, S-bend prototype was subjected to Paschen condition respectively at room temperature, 80 K and 5 K. The test was conducted in free and fatigue state tensile condition (100 times tensile cycles at low-temperature), used helium from 0.1Pa to 1000 Pa. The maximum voltage is 30 kV. The leakage current is less than 2.5µA in free state at room temperature. In fatigue state the leakage current is less than 350µA when the temperature is 5 K. All of the results can meet the ITER requirements where the leakage current shall be not higher than 30 µA when the voltage is 30kV.

The insulation procedure of S-bend prototype involved in the test is manual pre-impregnation with GKG insulation structure, and the thickness of insulation layer is 6 mm.

The experiment will have a positive effect on ITER Feeder insulation material selection, insulation technology exploration and test platform setup. At present, other high voltage insulation specimens of the Feeder are also in preparation in R&D Center.