70
4 Responses of Plasma-Facing Surface to Power Load Given by Radiation …
Fig. 4.20 Temperature dependence of He concentration in the injected region of Ni and Mo with
20 keV He + at the threshold fluence for burst-like He reemission (See Fig. 4.19). Temperature is
normalized to the melting temperature [32]
Fig. 4.21 Ionization and recombination of C ions in detached plasma in divertor region of JT60U. From the left, the radiation power from the ionizing plasma component, the ionization flux,
the spatial distribution of the emissivity, the recombination flux, and the radiation power from the
recombining plasma component of C 3+ (upper) and C 2+ (lower) (reprinted with permission from
[33])
In the case of W-wall, energy exhaust by such recombination process should not
be large because W erosion is much less than C erosion. To enhance power exhaust
in the divertor area, some impurity gases with low to medium Z number are planned
to be seeded intentionally in the boundary plasma in ITER and a reactor (impurity
seeding).
4 Responses of Plasma-Facing Surface to Power Load Given by Radiation …
Fig. 4.20 Temperature dependence of He concentration in the injected region of Ni and Mo with
20 keV He + at the threshold fluence for burst-like He reemission (See Fig. 4.19). Temperature is
normalized to the melting temperature [32]
Fig. 4.21 Ionization and recombination of C ions in detached plasma in divertor region of JT60U. From the left, the radiation power from the ionizing plasma component, the ionization flux,
the spatial distribution of the emissivity, the recombination flux, and the radiation power from the
recombining plasma component of C 3+ (upper) and C 2+ (lower) (reprinted with permission from
[33])
In the case of W-wall, energy exhaust by such recombination process should not
be large because W erosion is much less than C erosion. To enhance power exhaust
in the divertor area, some impurity gases with low to medium Z number are planned
to be seeded intentionally in the boundary plasma in ITER and a reactor (impurity
seeding).