9.4 Fuel Retention in Carbon Materials
173
Fig. 9.7 Comparison of fluence dependence of fuel retention for W-wall and C-wall. a Deuterium
retention in W exposed D plasma (ADEX-U) and D ions in various laboratories (reprinted with
permission from [26]) and references therein, and b Estimation of fuel retention in an ITER scale fullC reactor [10]. The vertical scales of left and right are given by 1 m −2 and 10 −2 m −2 , respectively,
for easy comparison
layers was taken to be T/C = 0.013 and 0.08 for the inner divertor and the outer dome
wing, respectively, instead of 0.4. T/C for the tile gaps was assumed to be 0.1–0.08.
Since a higher tile temperature above 600 K is foreseen in ITER and future plasma
devices, the fuel retention could be lower than the present estimation for ITER.
Based on the estimation given above, T retention could be significantly reduced
even using C as PFM, if tile temperature of a reactor was raised above 500 K as
JT-60U, it would significantly reduce the fuel retention even using full-C as PFM.
9.5 Fuel Retention in Tungsten (W)
Because no tokamaks with full W-wall are available, estimation of fuel retention in
a full W-wall reactor is quite hard and extrapolation of existing data on hydrogen
retention under energetic ion injection or plasma exposure to reactor like condition
is necessary. However, data of hydrogen retention in W are widely scattered and the
retention mechanism is not fully understood. Furthermore, formation of deposited
173
Fig. 9.7 Comparison of fluence dependence of fuel retention for W-wall and C-wall. a Deuterium
retention in W exposed D plasma (ADEX-U) and D ions in various laboratories (reprinted with
permission from [26]) and references therein, and b Estimation of fuel retention in an ITER scale fullC reactor [10]. The vertical scales of left and right are given by 1 m −2 and 10 −2 m −2 , respectively,
for easy comparison
layers was taken to be T/C = 0.013 and 0.08 for the inner divertor and the outer dome
wing, respectively, instead of 0.4. T/C for the tile gaps was assumed to be 0.1–0.08.
Since a higher tile temperature above 600 K is foreseen in ITER and future plasma
devices, the fuel retention could be lower than the present estimation for ITER.
Based on the estimation given above, T retention could be significantly reduced
even using C as PFM, if tile temperature of a reactor was raised above 500 K as
JT-60U, it would significantly reduce the fuel retention even using full-C as PFM.
9.5 Fuel Retention in Tungsten (W)
Because no tokamaks with full W-wall are available, estimation of fuel retention in
a full W-wall reactor is quite hard and extrapolation of existing data on hydrogen
retention under energetic ion injection or plasma exposure to reactor like condition
is necessary. However, data of hydrogen retention in W are widely scattered and the
retention mechanism is not fully understood. Furthermore, formation of deposited