Research of high heat flux for divertor materials

The HIP(hot isostatic press) technology was used to weld two kinds metal materials involving tungsten and copper which have a great difference in physic properties. The welding properties were discussed under different conditions. The fracture surface of the elements during the welding process were showed in this paper. It was found that the binding of tungsten and copper was mainly physical binding, they were linked by high temperature and high pressure because of the material surface under micro dimension. The diffusion was almost not found. The welding interface of copper and stainless steel has a good diffusion because of the incorporation of nickel. Thermal fatigue of the divertor plate is one of the key factors governing the lifetime of the divertor plate. The thermal cycling test of divertor target plate was carried out in the vacuum; a high heat flux electron gun was used as a thermal source. A cyclic heat flux of 9 MW/m''2 was loaded onto the target plate and a pulse duration of 20 s selected, with the cooling water flow rate of 80 ml/s. NiCr-NiSi thermocouples with diameter of 0.3 mm are used to test the temperature distribution of the specimen under 9 MW/m''2 power density in the vacuum. It is found that the highest temperature of the surface is 400 degree. The highest temperature at the welding seam of tungsten and copper is 150 degree. After 1000 cycles, the surface and the W/Cu joint of the target plate did not show any damage during the fatigue test. The calculation data conform with the testing result. It is conducted that the testing data are reliable