SURFACE DAMAGE AND SPUTTERING OF ATJ GRAPHITE AS CANDIDATE ARMOR PLATE MATERIAL FOR TFTR UNDER D+ BOMBARDMENT

Experiments have been conducted to determine surface damage and total sputtering yields of ATJ graphite (a candidate armor plate material) caused by D+ ion irradiation at 40-, 60-, and 120-keV for fluxes close to those expected to reach the armor plate during the operation of neutral beam injectors used for the Tokamak Fusion Test Reactor (TFTR). The irradiations for surface damage studies were conducted both in the pulsed mode and in the continuous mode. Scanning electron microscopy of irradiated surfaces revealed surface damage in the form of ridges and grooves for both pulsed and continuous irradiations. Total sputtering yields for ATJ graphite samples which reached surface temperatures characteristic for given beam power depositions are given for 40-, 60-, and 120-keV D+ irradiations at normal incidence. © 1979.