154
8 PMI in Large Tokamaks
Total D retenƟon rate
JET-C 2001-2004
6g
3.7%
JET-C 2007-2009
~50g
2.1%
JET-ILW 2010-2012
1.5g
(a)
(b)
Fig. 8.13 a Comparison of calculated and experimental D retention rates for JET-ILW and CJET with WallDYN calculations. Also shown are the WallDYN predictions for Be +W (Case B)
and a full C-ITER (Case C) (reprinted with permission from [39]), b Deuterium gas injection rate
during the main heating phase as a function of absorbed power for the four power scan experiments
(reprinted with permission from [40])
ILW requires more hydrogen throughput than that required for the C-wall, while
the static retention is large in the latter nearly 50 times. It should be noted that the
retention characteristics are quite dependent on the wall temperature with less for
high temperatures. In this respect, the retention in ITER would be far less than that
in JET. In Chap. 9, estimation of fuel retention in a reactor is described in detail [41].
In the next section, D retention in present large machines mostly having the C-wall
are summarized.
8.4.3.2 Summary of Deuterium Retention in Present Tokamaks Using
DD discharges
Current estimation of T retention in ITER is based on studies of D retention in tokamaks with DD discharges (Deuterium plasma heated by Deuterium neutral beam),
of which PFS is mostly composed of C. The results of these studies are summarized
in this section [19–22].
In most tokamaks, as already discussed, C tiles at the outer divertor area are
eroded and those at the inner divertor area deposited by the eroded carbon. However,
materials balance between the erosion at the outer divertor and the deposition at the
inner divertor is missing as shown in Fig. 5.1. The former is less than the latter, and the
missing mass is likely compensated by erosion of the first wall of the main chamber,
for which no systematic measurements have been done. The carbon deposition occurs
by repetitive processes of erosion and prompt deposition of the eroded carbon as
8 PMI in Large Tokamaks
Total D retenƟon rate
JET-C 2001-2004
6g
3.7%
JET-C 2007-2009
~50g
2.1%
JET-ILW 2010-2012
1.5g
(a)
(b)
Fig. 8.13 a Comparison of calculated and experimental D retention rates for JET-ILW and CJET with WallDYN calculations. Also shown are the WallDYN predictions for Be +W (Case B)
and a full C-ITER (Case C) (reprinted with permission from [39]), b Deuterium gas injection rate
during the main heating phase as a function of absorbed power for the four power scan experiments
(reprinted with permission from [40])
ILW requires more hydrogen throughput than that required for the C-wall, while
the static retention is large in the latter nearly 50 times. It should be noted that the
retention characteristics are quite dependent on the wall temperature with less for
high temperatures. In this respect, the retention in ITER would be far less than that
in JET. In Chap. 9, estimation of fuel retention in a reactor is described in detail [41].
In the next section, D retention in present large machines mostly having the C-wall
are summarized.
8.4.3.2 Summary of Deuterium Retention in Present Tokamaks Using
DD discharges
Current estimation of T retention in ITER is based on studies of D retention in tokamaks with DD discharges (Deuterium plasma heated by Deuterium neutral beam),
of which PFS is mostly composed of C. The results of these studies are summarized
in this section [19–22].
In most tokamaks, as already discussed, C tiles at the outer divertor area are
eroded and those at the inner divertor area deposited by the eroded carbon. However,
materials balance between the erosion at the outer divertor and the deposition at the
inner divertor is missing as shown in Fig. 5.1. The former is less than the latter, and the
missing mass is likely compensated by erosion of the first wall of the main chamber,
for which no systematic measurements have been done. The carbon deposition occurs
by repetitive processes of erosion and prompt deposition of the eroded carbon as