Deuterium retention in carbon dust and carbon–tungsten mixed dust prepared by deuterium arc discharge

Deuterium retentions in carbon dust and carbon–tungsten mixed dust (C–W dust) were investigated to estimate the tritium inventory in fusion experimental reactors. Several types of carbon dust or C–W dust were prepared by D2 arc discharge using carbon or carbon–tungsten electrodes, respectively. These were prepared by changing substrate temperatures with discharge pressure of 1.6 Pa. Deuterium retained in carbon dust was desorbed in the form of D2, HD, CD4 and C2D4. The peak temperature of the D2 desorption rate was 1100 K. On the other hand, the deuterium retained in C–W dust was desorbed mainly in the form of D2 and HD. The peak temperature of the D2 desorption rate was 900 K. The deuterium concentrations in the atomic ratio, D/C, for carbon dust and C–W dust (C/W=70/30) were reduced from 0.33 to 0.12 and from 0.7 to 0.07, respectively, when the substrate temperature increased from 300 to 850 K.