Roughened surface study on japanese test coil for the large coil task

The Japanese test coil for the Large Coil Task utilizes a pool cooling method. In order to get better stabilization in the coil, many different roughened surfaces were investigated. Chemically oxidized Thermo-excel-C surface was selected as the cooling surface for the Japanese LCT conductor. The steady state boiling helium heat transfer characteristics of this surface were measured, and even with the coil simulating long narrow cooling channel its equal area heat flux is more than 1.0 W/cm². Stability of the Japanese LCT conductor was analyzed using measured data, and the conductor proved to be sufficiently stable.