Measurement of Contact Resistance and Heat Load Test on Graphite Limiter

Abstract

A simple graphite limiter has been designed for high heat load in a tokamak device. The thermal contact conductance α_c was measured as the function of contacting pressure p, because α_c, is an important parameter for the graphite limiter design. Both experiments on small samples and full scale limiter assembly provided consistent data of α_c=0.1 W/cm²•°C at p=1 kgf/cm² (0.1 MPa). This value is considered to be sufficiently large from the viewpoint of the limiter thermal design.
Heat load test was performed on the simple graphite limiter by using electron beam. Two kinds of materials employed in the test were POCO graphite and SIC-6 graphite which has thermal expansion coefficient similar to that of SiC. The test results showed that both graphite materials had enough thermal shock resistance to the heat load q=500 W/cm², t=320 s, and SiC coating on SIC-6 graphite had better behavior against thermal shock, comparing with TiC coating on POCO graphite.