High energy neutron and charged particle irradiation effects on thermomechanical properties of carbon–carbon composites for divertor applications

Abstract

To assess the degradation of carbon–carbon (C/C) composite materials for the divertor structure, 14 MeV neutron and charged particle simulation irradiations were performed on several grades of C/C composites. For the charged particle irradiation the damage to be caused was also estimated using EDEP-1 code. Materials used were several grades of C/C composites, all of which were used in the JT-60 as divertor armor tiles. The measurement of thermal diffusivity up to 1600 K, electrical resistivity during 14 MeV neutron irradiation and the micro-indentation test at room temperature were performed. The strength and Young's modulus were evaluated on the basis of the result of micro-indentation test. Main results are: (1) The maximum of the microhardness was found near the maximum projected range of the C/C composite for charged particles. (2) After the irradiation of 10 MeV protons (<0.1 dpa), 10–90% increases in tensile strength and Young's modulus were observed, depending on the grades of C/C composites. (3) Softening of C/C composites was observed in the micro-indentation test when they were irradiated by 14 MeV neutrons up to a fluence of 10 19 n/m 2 .