Manufacturing and high heat flux testing of flat-type W/Cu/CuCrZr mock-up by HIP assisted brazing process

Abstract

Divertor is one of the most challenging plasma facing components (PFCs) for fusion reactors both from the design and fabrication technology point of view. In this work, the new flat-type W/Cu/CuCrZr mock-ups were fabricated using hot isostatic pressing (HIP) and optimized brazing techniques. High heat flux (HHF) tests of the mock-up were performed on a comprehensive experimental platform to assess the heat removal capability and thermal fatigue resistance. The results indicate that the mock-up successfully endured the cyclic absorbed heat flux at 20 MW m−2 for 1000 cycles with an inlet pressure of 1 MPa, an inlet water temperature of 20 °C and a velocity of 6.88 m s−1. The peak temperature of the tungsten (W) surface reached 926 °C at the 1000th cycle, which is less than the recrystallization temperature. In addition, no substantial melting at the loaded W surfaces, no detachment of any W/Cu units and no occurrence of any ‘hot spot’ during thermal fatigue cycling were observed. These results indicate that HIP assisted brazing technique is a powerful method for fabricating PFCs employed in HHF tests, and the flat-type W/Cu/CuCrZr structure is very promising to be used to upgrade the lower divertor of Experimental Advanced Superconducting Tokamak(EAST) and manufacture the divertor for China Fusion Engineering Test Reactor(CFETR).